uwb: improved MAS allocator and reservation conflict handling

Greatly enhance the MAS allocator:
- Handle row and column reservations.
- Permit all the available MAS to be allocated.
- Follows the WiMedia rules on MAS selection.

Take appropriate action when reservation conflicts are detected.
- Correctly identify which reservation wins the conflict.
- Protect alien BP reservations.
- If an owned reservation loses, resize/move it.
- Follow the backoff procedure before requesting additional MAS.

When reservations are terminated, move the remaining reservations (if
necessary) so they keep following the MAS allocation rules.

Signed-off-by: Stefano Panella <[e-mail]>
Signed-off-by: David Vrabel <[e-mail]>

drivers/usb/wusbcore/reservation.c

···
 {
 	struct wusbhc *wusbhc = rsv->pal_priv;
 	struct device *dev = wusbhc->dev;
+	struct uwb_mas_bm mas;
 	char buf[72];
 
 	switch (rsv->state) {
 	case UWB_RSV_STATE_O_ESTABLISHED:
-		bitmap_scnprintf(buf, sizeof(buf), rsv->mas.bm, UWB_NUM_MAS);
+		uwb_rsv_get_usable_mas(rsv, &mas);
+		bitmap_scnprintf(buf, sizeof(buf), mas.bm, UWB_NUM_MAS);
 		dev_dbg(dev, "established reservation: %s\n", buf);
-		wusbhc_bwa_set(wusbhc, rsv->stream, &rsv->mas);
+		wusbhc_bwa_set(wusbhc, rsv->stream, &mas);
 		break;
 	case UWB_RSV_STATE_NONE:
 		dev_dbg(dev, "removed reservation\n");
···
 	bcid.data[0] = wusbhc->cluster_id;
 	bcid.data[1] = 0;
 
-	rsv->owner = &rc->uwb_dev;
 	rsv->target.type = UWB_RSV_TARGET_DEVADDR;
 	rsv->target.devaddr = bcid;
 	rsv->type = UWB_DRP_TYPE_PRIVATE;
-	rsv->max_mas = 256;
-	rsv->min_mas = 16;  /* one MAS per zone? */
-	rsv->sparsity = 16; /* at least one MAS in each zone? */
+	rsv->max_mas = 256; /* try to get as much as possible */
+	rsv->min_mas = 15;  /* one MAS per zone */
+	rsv->max_interval = 1; /* max latency is one zone */
 	rsv->is_multicast = true;
 
 	ret = uwb_rsv_establish(rsv);

drivers/uwb/Makefile

···
 
 uwb-objs :=		\
 	address.o	\
+	allocator.o	\
 	beacon.o	\
 	driver.o	\
 	drp.o		\

drivers/uwb/allocator.c

···
+/*
+ * UWB reservation management.
+ *
+ * Copyright (C) 2008 Cambridge Silicon Radio Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/version.h>
+#include <linux/kernel.h>
+#include <linux/uwb.h>
+
+#include "uwb-internal.h"
+
+static void uwb_rsv_fill_column_alloc(struct uwb_rsv_alloc_info *ai)
+{
+	int col, mas, safe_mas, unsafe_mas;
+	unsigned char *bm = ai->bm;
+	struct uwb_rsv_col_info *ci = ai->ci;
+	unsigned char c;
+
+	for (col = ci->csi.start_col; col < UWB_NUM_ZONES; col += ci->csi.interval) {
+    
+		safe_mas   = ci->csi.safe_mas_per_col;
+		unsafe_mas = ci->csi.unsafe_mas_per_col;
+    
+		for (mas = 0; mas < UWB_MAS_PER_ZONE; mas++ ) {
+			if (bm[col * UWB_MAS_PER_ZONE + mas] == 0) {
+	
+				if (safe_mas > 0) {
+					safe_mas--;
+					c = UWB_RSV_MAS_SAFE;
+				} else if (unsafe_mas > 0) {
+					unsafe_mas--;
+					c = UWB_RSV_MAS_UNSAFE;
+				} else {
+					break;
+				}
+				bm[col * UWB_MAS_PER_ZONE + mas] = c;
+			}
+		}
+	}
+}
+
+static void uwb_rsv_fill_row_alloc(struct uwb_rsv_alloc_info *ai)
+{
+	int mas, col, rows;
+	unsigned char *bm = ai->bm;
+	struct uwb_rsv_row_info *ri = &ai->ri;
+	unsigned char c;
+
+	rows = 1;
+	c = UWB_RSV_MAS_SAFE;
+	for (mas = UWB_MAS_PER_ZONE - 1; mas >= 0; mas--) {
+		if (ri->avail[mas] == 1) {
+      
+			if (rows > ri->used_rows) {
+				break;
+			} else if (rows > 7) {
+				c = UWB_RSV_MAS_UNSAFE;
+			}
+
+			for (col = 0; col < UWB_NUM_ZONES; col++) {
+				if (bm[col * UWB_NUM_ZONES + mas] != UWB_RSV_MAS_NOT_AVAIL) {
+					bm[col * UWB_NUM_ZONES + mas] = c;
+					if(c == UWB_RSV_MAS_SAFE)
+						ai->safe_allocated_mases++;
+					else
+						ai->unsafe_allocated_mases++;
+				}
+			}
+			rows++;
+		}
+	}
+	ai->total_allocated_mases = ai->safe_allocated_mases + ai->unsafe_allocated_mases;
+}
+
+/*
+ * Find the best column set for a given availability, interval, num safe mas and
+ * num unsafe mas.
+ *
+ * The different sets are tried in order as shown below, depending on the interval.
+ *
+ * interval = 16
+ *	deep = 0
+ *		set 1 ->  {  8 }
+ *	deep = 1
+ *		set 1 ->  {  4 }
+ *		set 2 ->  { 12 }
+ *	deep = 2
+ *		set 1 ->  {  2 }
+ *		set 2 ->  {  6 }
+ *		set 3 ->  { 10 }
+ *		set 4 ->  { 14 }
+ *	deep = 3
+ *		set 1 ->  {  1 }
+ *		set 2 ->  {  3 }
+ *		set 3 ->  {  5 }
+ *		set 4 ->  {  7 }
+ *		set 5 ->  {  9 }
+ *		set 6 ->  { 11 }
+ *		set 7 ->  { 13 }
+ *		set 8 ->  { 15 }
+ *
+ * interval = 8
+ *	deep = 0
+ *		set 1 ->  {  4  12 }
+ *	deep = 1
+ *		set 1 ->  {  2  10 }
+ *		set 2 ->  {  6  14 }
+ *	deep = 2
+ *		set 1 ->  {  1   9 }
+ *		set 2 ->  {  3  11 }
+ *		set 3 ->  {  5  13 }
+ *		set 4 ->  {  7  15 }
+ *
+ * interval = 4
+ *	deep = 0
+ *		set 1 ->  {  2   6  10  14 }
+ *	deep = 1
+ *		set 1 ->  {  1   5   9  13 }
+ *		set 2 ->  {  3   7  11  15 }
+ *
+ * interval = 2
+ *	deep = 0
+ *		set 1 ->  {  1   3   5   7   9  11  13  15 }
+ */
+static int uwb_rsv_find_best_column_set(struct uwb_rsv_alloc_info *ai, int interval, 
+					int num_safe_mas, int num_unsafe_mas)
+{
+	struct uwb_rsv_col_info *ci = ai->ci;
+	struct uwb_rsv_col_set_info *csi = &ci->csi;
+	struct uwb_rsv_col_set_info tmp_csi;
+	int deep, set, col, start_col_deep, col_start_set;
+	int start_col, max_mas_in_set, lowest_max_mas_in_deep;
+	int n_mas;
+	int found = UWB_RSV_ALLOC_NOT_FOUND; 
+
+	tmp_csi.start_col = 0;
+	start_col_deep = interval;
+	n_mas = num_unsafe_mas + num_safe_mas;
+
+	for (deep = 0; ((interval >> deep) & 0x1) == 0; deep++) {
+		start_col_deep /= 2;
+		col_start_set = 0;
+		lowest_max_mas_in_deep = UWB_MAS_PER_ZONE;
+
+		for (set = 1; set <= (1 << deep); set++) {
+			max_mas_in_set = 0;
+			start_col = start_col_deep + col_start_set;
+			for (col = start_col; col < UWB_NUM_ZONES; col += interval) {
+                
+				if (ci[col].max_avail_safe >= num_safe_mas &&
+				    ci[col].max_avail_unsafe >= n_mas) {
+					if (ci[col].highest_mas[n_mas] > max_mas_in_set)
+						max_mas_in_set = ci[col].highest_mas[n_mas];
+				} else {
+					max_mas_in_set = 0;
+					break;
+				}
+			}
+			if ((lowest_max_mas_in_deep > max_mas_in_set) && max_mas_in_set) {
+				lowest_max_mas_in_deep = max_mas_in_set;
+
+				tmp_csi.start_col = start_col;
+			}
+			col_start_set += (interval >> deep);
+		}
+
+		if (lowest_max_mas_in_deep < 8) {
+			csi->start_col = tmp_csi.start_col;
+			found = UWB_RSV_ALLOC_FOUND;
+			break;
+		} else if ((lowest_max_mas_in_deep > 8) && 
+			   (lowest_max_mas_in_deep != UWB_MAS_PER_ZONE) &&
+			   (found == UWB_RSV_ALLOC_NOT_FOUND)) {
+			csi->start_col = tmp_csi.start_col;
+			found = UWB_RSV_ALLOC_FOUND;
+		}
+	}
+
+	if (found == UWB_RSV_ALLOC_FOUND) {
+		csi->interval = interval;
+		csi->safe_mas_per_col = num_safe_mas;
+		csi->unsafe_mas_per_col = num_unsafe_mas;
+
+		ai->safe_allocated_mases = (UWB_NUM_ZONES / interval) * num_safe_mas;
+		ai->unsafe_allocated_mases = (UWB_NUM_ZONES / interval) * num_unsafe_mas;
+		ai->total_allocated_mases = ai->safe_allocated_mases + ai->unsafe_allocated_mases;
+		ai->interval = interval;		
+	}
+	return found;
+}
+
+static void get_row_descriptors(struct uwb_rsv_alloc_info *ai)
+{
+	unsigned char *bm = ai->bm;
+	struct uwb_rsv_row_info *ri = &ai->ri;
+	int col, mas;
+  
+	ri->free_rows = 16;
+	for (mas = 0; mas < UWB_MAS_PER_ZONE; mas ++) {
+		ri->avail[mas] = 1;
+		for (col = 1; col < UWB_NUM_ZONES; col++) {
+			if (bm[col * UWB_NUM_ZONES + mas] == UWB_RSV_MAS_NOT_AVAIL) {
+				ri->free_rows--;
+				ri->avail[mas]=0;
+				break;
+			}
+		}
+	}
+}
+
+static void uwb_rsv_fill_column_info(unsigned char *bm, int column, struct uwb_rsv_col_info *rci)
+{
+	int mas;
+	int block_count = 0, start_block = 0; 
+	int previous_avail = 0;
+	int available = 0;
+	int safe_mas_in_row[UWB_MAS_PER_ZONE] = {
+		8, 7, 6, 5, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 2, 1,
+	};
+
+	rci->max_avail_safe = 0;
+
+	for (mas = 0; mas < UWB_MAS_PER_ZONE; mas ++) {
+		if (!bm[column * UWB_NUM_ZONES + mas]) {
+			available++;
+			rci->max_avail_unsafe = available;
+
+			rci->highest_mas[available] = mas;
+
+			if (previous_avail) {
+				block_count++;
+				if ((block_count > safe_mas_in_row[start_block]) &&
+				    (!rci->max_avail_safe))
+					rci->max_avail_safe = available - 1;
+			} else {
+				previous_avail = 1;
+				start_block = mas;
+				block_count = 1;
+			}
+		} else {
+			previous_avail = 0;
+		}
+	}
+	if (!rci->max_avail_safe)
+		rci->max_avail_safe = rci->max_avail_unsafe;
+}
+
+static void get_column_descriptors(struct uwb_rsv_alloc_info *ai)
+{
+	unsigned char *bm = ai->bm;
+	struct uwb_rsv_col_info *ci = ai->ci;
+	int col;
+
+	for (col = 1; col < UWB_NUM_ZONES; col++) {
+		uwb_rsv_fill_column_info(bm, col, &ci[col]);
+	}
+}
+
+static int uwb_rsv_find_best_row_alloc(struct uwb_rsv_alloc_info *ai)
+{
+	int n_rows;
+	int max_rows = ai->max_mas / UWB_USABLE_MAS_PER_ROW;
+	int min_rows = ai->min_mas / UWB_USABLE_MAS_PER_ROW;
+	if (ai->min_mas % UWB_USABLE_MAS_PER_ROW)
+		min_rows++;
+	for (n_rows = max_rows; n_rows >= min_rows; n_rows--) {
+		if (n_rows <= ai->ri.free_rows) {
+			ai->ri.used_rows = n_rows;
+			ai->interval = 1; /* row reservation */
+			uwb_rsv_fill_row_alloc(ai);
+			return UWB_RSV_ALLOC_FOUND;
+		}
+	}  
+	return UWB_RSV_ALLOC_NOT_FOUND;
+}
+
+static int uwb_rsv_find_best_col_alloc(struct uwb_rsv_alloc_info *ai, int interval)
+{
+	int n_safe, n_unsafe, n_mas;  
+	int n_column = UWB_NUM_ZONES / interval;
+	int max_per_zone = ai->max_mas / n_column;
+	int min_per_zone = ai->min_mas / n_column;
+
+	if (ai->min_mas % n_column)
+		min_per_zone++;
+
+	if (min_per_zone > UWB_MAS_PER_ZONE) {
+		return UWB_RSV_ALLOC_NOT_FOUND;
+	}
+    
+	if (max_per_zone > UWB_MAS_PER_ZONE) {
+		max_per_zone = UWB_MAS_PER_ZONE;
+	}
+    
+	for (n_mas = max_per_zone; n_mas >= min_per_zone; n_mas--) {
+		if (uwb_rsv_find_best_column_set(ai, interval, 0, n_mas) == UWB_RSV_ALLOC_NOT_FOUND)
+			continue;
+		for (n_safe = n_mas; n_safe >= 0; n_safe--) {
+			n_unsafe = n_mas - n_safe;
+			if (uwb_rsv_find_best_column_set(ai, interval, n_safe, n_unsafe) == UWB_RSV_ALLOC_FOUND) {
+				uwb_rsv_fill_column_alloc(ai);
+				return UWB_RSV_ALLOC_FOUND;
+			}
+		}
+	}
+	return UWB_RSV_ALLOC_NOT_FOUND;
+}
+
+int uwb_rsv_find_best_allocation(struct uwb_rsv *rsv, struct uwb_mas_bm *available, 
+				 struct uwb_mas_bm *result)
+{
+	struct uwb_rsv_alloc_info *ai;
+	int interval;
+	int bit_index;
+
+	ai = kzalloc(sizeof(struct uwb_rsv_alloc_info), GFP_KERNEL);
+	
+	ai->min_mas = rsv->min_mas;
+	ai->max_mas = rsv->max_mas;
+	ai->max_interval = rsv->max_interval;
+
+
+	/* fill the not available vector from the available bm */
+	for (bit_index = 0; bit_index < UWB_NUM_MAS; bit_index++) {
+		if (!test_bit(bit_index, available->bm))
+			ai->bm[bit_index] = UWB_RSV_MAS_NOT_AVAIL;
+	}
+
+	if (ai->max_interval == 1) {
+		get_row_descriptors(ai);
+		if (uwb_rsv_find_best_row_alloc(ai) == UWB_RSV_ALLOC_FOUND)
+			goto alloc_found;
+		else
+			goto alloc_not_found;
+	}
+
+	get_column_descriptors(ai);
+        
+	for (interval = 16; interval >= 2; interval>>=1) {
+		if (interval > ai->max_interval)
+			continue;
+		if (uwb_rsv_find_best_col_alloc(ai, interval) == UWB_RSV_ALLOC_FOUND)
+			goto alloc_found;
+	}
+
+	/* try row reservation if no column is found */
+	get_row_descriptors(ai);
+	if (uwb_rsv_find_best_row_alloc(ai) == UWB_RSV_ALLOC_FOUND)
+		goto alloc_found;
+	else
+		goto alloc_not_found;
+
+  alloc_found:
+	bitmap_zero(result->bm, UWB_NUM_MAS);
+	bitmap_zero(result->unsafe_bm, UWB_NUM_MAS);
+	/* fill the safe and unsafe bitmaps */
+	for (bit_index = 0; bit_index < UWB_NUM_MAS; bit_index++) {
+		if (ai->bm[bit_index] == UWB_RSV_MAS_SAFE)
+			set_bit(bit_index, result->bm);
+		else if (ai->bm[bit_index] == UWB_RSV_MAS_UNSAFE)
+			set_bit(bit_index, result->unsafe_bm);
+	}
+	bitmap_or(result->bm, result->bm, result->unsafe_bm, UWB_NUM_MAS);
+
+	result->safe   = ai->safe_allocated_mases;
+	result->unsafe = ai->unsafe_allocated_mases;
+	
+	kfree(ai);		
+	return UWB_RSV_ALLOC_FOUND;
+  
+  alloc_not_found:
+	kfree(ai);
+	return UWB_RSV_ALLOC_NOT_FOUND;
+}

drivers/uwb/drp-avail.c

···
  *
  * avail = global & local & pending
  */
-static void uwb_drp_available(struct uwb_rc *rc, struct uwb_mas_bm *avail)
+void uwb_drp_available(struct uwb_rc *rc, struct uwb_mas_bm *avail)
 {
 	bitmap_and(avail->bm, rc->drp_avail.global, rc->drp_avail.local, UWB_NUM_MAS);
 	bitmap_and(avail->bm, avail->bm, rc->drp_avail.pending, UWB_NUM_MAS);
···
 	bitmap_or(rc->drp_avail.local, rc->drp_avail.local, mas->bm, UWB_NUM_MAS);
 	bitmap_or(rc->drp_avail.pending, rc->drp_avail.pending, mas->bm, UWB_NUM_MAS);
 	rc->drp_avail.ie_valid = false;
+	uwb_rsv_handle_drp_avail_change(rc);
 }
 
 /**
···
 	mutex_lock(&rc->rsvs_mutex);
 	bitmap_copy(rc->drp_avail.global, bmp, UWB_NUM_MAS);
 	rc->drp_avail.ie_valid = false;
+	uwb_rsv_handle_drp_avail_change(rc);
 	mutex_unlock(&rc->rsvs_mutex);
 
 	uwb_rsv_sched_update(rc);

drivers/uwb/drp-ie.c

···
 
 #include "uwb-internal.h"
 
+
+/*
+ * Return the reason code for a reservations's DRP IE.
+ */
+int uwb_rsv_reason_code(struct uwb_rsv *rsv)
+{
+	static const int reason_codes[] = {
+		[UWB_RSV_STATE_O_INITIATED]          = UWB_DRP_REASON_ACCEPTED,
+		[UWB_RSV_STATE_O_PENDING]            = UWB_DRP_REASON_ACCEPTED,
+		[UWB_RSV_STATE_O_MODIFIED]           = UWB_DRP_REASON_MODIFIED,
+		[UWB_RSV_STATE_O_ESTABLISHED]        = UWB_DRP_REASON_ACCEPTED,
+		[UWB_RSV_STATE_O_TO_BE_MOVED]        = UWB_DRP_REASON_ACCEPTED,
+		[UWB_RSV_STATE_O_MOVE_COMBINING]     = UWB_DRP_REASON_MODIFIED,
+		[UWB_RSV_STATE_O_MOVE_REDUCING]      = UWB_DRP_REASON_MODIFIED,
+		[UWB_RSV_STATE_O_MOVE_EXPANDING]     = UWB_DRP_REASON_ACCEPTED,
+		[UWB_RSV_STATE_T_ACCEPTED]           = UWB_DRP_REASON_ACCEPTED,
+		[UWB_RSV_STATE_T_CONFLICT]           = UWB_DRP_REASON_CONFLICT,
+		[UWB_RSV_STATE_T_PENDING]            = UWB_DRP_REASON_PENDING,
+		[UWB_RSV_STATE_T_DENIED]             = UWB_DRP_REASON_DENIED,
+		[UWB_RSV_STATE_T_RESIZED]            = UWB_DRP_REASON_ACCEPTED,
+		[UWB_RSV_STATE_T_EXPANDING_ACCEPTED] = UWB_DRP_REASON_ACCEPTED,
+		[UWB_RSV_STATE_T_EXPANDING_CONFLICT] = UWB_DRP_REASON_CONFLICT,
+		[UWB_RSV_STATE_T_EXPANDING_PENDING]  = UWB_DRP_REASON_PENDING,
+		[UWB_RSV_STATE_T_EXPANDING_DENIED]   = UWB_DRP_REASON_DENIED,
+	};
+
+	return reason_codes[rsv->state];
+}
+
+/*
+ * Return the reason code for a reservations's companion DRP IE .
+ */
+int uwb_rsv_companion_reason_code(struct uwb_rsv *rsv)
+{
+	static const int companion_reason_codes[] = {
+		[UWB_RSV_STATE_O_MOVE_EXPANDING]     = UWB_DRP_REASON_ACCEPTED,
+		[UWB_RSV_STATE_T_EXPANDING_ACCEPTED] = UWB_DRP_REASON_ACCEPTED,
+		[UWB_RSV_STATE_T_EXPANDING_CONFLICT] = UWB_DRP_REASON_CONFLICT,
+		[UWB_RSV_STATE_T_EXPANDING_PENDING]  = UWB_DRP_REASON_PENDING,
+		[UWB_RSV_STATE_T_EXPANDING_DENIED]   = UWB_DRP_REASON_DENIED,
+	};
+
+	return companion_reason_codes[rsv->state];
+}
+
+/*
+ * Return the status bit for a reservations's DRP IE.
+ */
+int uwb_rsv_status(struct uwb_rsv *rsv)
+{
+	static const int statuses[] = {
+		[UWB_RSV_STATE_O_INITIATED]          = 0,
+		[UWB_RSV_STATE_O_PENDING]            = 0,
+		[UWB_RSV_STATE_O_MODIFIED]           = 1,
+		[UWB_RSV_STATE_O_ESTABLISHED]        = 1,
+		[UWB_RSV_STATE_O_TO_BE_MOVED]        = 0,
+		[UWB_RSV_STATE_O_MOVE_COMBINING]     = 1,
+		[UWB_RSV_STATE_O_MOVE_REDUCING]      = 1,
+		[UWB_RSV_STATE_O_MOVE_EXPANDING]     = 1,
+		[UWB_RSV_STATE_T_ACCEPTED]           = 1,
+		[UWB_RSV_STATE_T_CONFLICT]           = 0,
+		[UWB_RSV_STATE_T_PENDING]            = 0,
+		[UWB_RSV_STATE_T_DENIED]             = 0,
+		[UWB_RSV_STATE_T_RESIZED]            = 1,
+		[UWB_RSV_STATE_T_EXPANDING_ACCEPTED] = 1,
+		[UWB_RSV_STATE_T_EXPANDING_CONFLICT] = 1,
+		[UWB_RSV_STATE_T_EXPANDING_PENDING]  = 1,
+		[UWB_RSV_STATE_T_EXPANDING_DENIED]   = 1,
+
+	};
+
+	return statuses[rsv->state];
+}
+
+/*
+ * Return the status bit for a reservations's companion DRP IE .
+ */
+int uwb_rsv_companion_status(struct uwb_rsv *rsv)
+{
+	static const int companion_statuses[] = {
+		[UWB_RSV_STATE_O_MOVE_EXPANDING]     = 0,
+		[UWB_RSV_STATE_T_EXPANDING_ACCEPTED] = 1,
+		[UWB_RSV_STATE_T_EXPANDING_CONFLICT] = 0,
+		[UWB_RSV_STATE_T_EXPANDING_PENDING]  = 0,
+		[UWB_RSV_STATE_T_EXPANDING_DENIED]   = 0,
+	};
+
+	return companion_statuses[rsv->state];
+}
+
 /*
  * Allocate a DRP IE.
  *
···
 static struct uwb_ie_drp *uwb_drp_ie_alloc(void)
 {
 	struct uwb_ie_drp *drp_ie;
-	unsigned tiebreaker;
 
 	drp_ie = kzalloc(sizeof(struct uwb_ie_drp) +
 			UWB_NUM_ZONES * sizeof(struct uwb_drp_alloc),
 			GFP_KERNEL);
 	if (drp_ie) {
 		drp_ie->hdr.element_id = UWB_IE_DRP;
-
-		get_random_bytes(&tiebreaker, sizeof(unsigned));
-		uwb_ie_drp_set_tiebreaker(drp_ie, tiebreaker & 1);
 	}
 	return drp_ie;
 }
···
  */
 int uwb_drp_ie_update(struct uwb_rsv *rsv)
 {
-	struct device *dev = &rsv->rc->uwb_dev.dev;
 	struct uwb_ie_drp *drp_ie;
-	int reason_code, status;
+	struct uwb_rsv_move *mv;
+	int unsafe;
 
-	switch (rsv->state) {
-	case UWB_RSV_STATE_NONE:
+	if (rsv->state == UWB_RSV_STATE_NONE) {
 		kfree(rsv->drp_ie);
 		rsv->drp_ie = NULL;
 		return 0;
-	case UWB_RSV_STATE_O_INITIATED:
-		reason_code = UWB_DRP_REASON_ACCEPTED;
-		status = 0;
-		break;
-	case UWB_RSV_STATE_O_PENDING:
-		reason_code = UWB_DRP_REASON_ACCEPTED;
-		status = 0;
-		break;
-	case UWB_RSV_STATE_O_MODIFIED:
-		reason_code = UWB_DRP_REASON_MODIFIED;
-		status = 1;
-		break;
-	case UWB_RSV_STATE_O_ESTABLISHED:
-		reason_code = UWB_DRP_REASON_ACCEPTED;
-		status = 1;
-		break;
-	case UWB_RSV_STATE_T_ACCEPTED:
-		reason_code = UWB_DRP_REASON_ACCEPTED;
-		status = 1;
-		break;
-	case UWB_RSV_STATE_T_DENIED:
-		reason_code = UWB_DRP_REASON_DENIED;
-		status = 0;
-		break;
-	default:
-		dev_dbg(dev, "rsv with unhandled state (%d)\n", rsv->state);
-		return -EINVAL;
 	}
+	
+	unsafe = rsv->mas.unsafe ? 1 : 0;
 
 	if (rsv->drp_ie == NULL) {
 		rsv->drp_ie = uwb_drp_ie_alloc();
···
 	}
 	drp_ie = rsv->drp_ie;
 
+	uwb_ie_drp_set_unsafe(drp_ie,       unsafe);
+	uwb_ie_drp_set_tiebreaker(drp_ie,   rsv->tiebreaker);
 	uwb_ie_drp_set_owner(drp_ie,        uwb_rsv_is_owner(rsv));
-	uwb_ie_drp_set_status(drp_ie,       status);
-	uwb_ie_drp_set_reason_code(drp_ie,  reason_code);
+	uwb_ie_drp_set_status(drp_ie,       uwb_rsv_status(rsv));
+	uwb_ie_drp_set_reason_code(drp_ie,  uwb_rsv_reason_code(rsv));
 	uwb_ie_drp_set_stream_index(drp_ie, rsv->stream);
 	uwb_ie_drp_set_type(drp_ie,         rsv->type);
 
···
 		drp_ie->dev_addr = rsv->owner->dev_addr;
 
 	uwb_drp_ie_from_bm(drp_ie, &rsv->mas);
+
+	if (uwb_rsv_has_two_drp_ies(rsv)) {
+		mv = &rsv->mv; 
+		if (mv->companion_drp_ie == NULL) {
+			mv->companion_drp_ie = uwb_drp_ie_alloc();
+			if (mv->companion_drp_ie == NULL)
+				return -ENOMEM;
+		}
+		drp_ie = mv->companion_drp_ie;
+		
+		/* keep all the same configuration of the main drp_ie */
+		memcpy(drp_ie, rsv->drp_ie, sizeof(struct uwb_ie_drp));
+		
+
+		/* FIXME: handle properly the unsafe bit */
+		uwb_ie_drp_set_unsafe(drp_ie,       1);
+		uwb_ie_drp_set_status(drp_ie,       uwb_rsv_companion_status(rsv));
+		uwb_ie_drp_set_reason_code(drp_ie,  uwb_rsv_companion_reason_code(rsv));
+	
+		uwb_drp_ie_from_bm(drp_ie, &mv->companion_mas);
+	}
 
 	rsv->ie_valid = true;
 	return 0;
···
 	u8 zone;
 	u16 zone_mask;
 
+	bitmap_zero(bm->bm, UWB_NUM_MAS);
+
 	for (cnt = 0; cnt < numallocs; cnt++) {
 		alloc = &drp_ie->allocs[cnt];
 		zone_bm = le16_to_cpu(alloc->zone_bm);
···
 		}
 	}
 }
+

drivers/uwb/drp.c

···
 #include <linux/delay.h>
 #include "uwb-internal.h"
 
+
+/* DRP Conflict Actions ([ECMA-368 2nd Edition] 17.4.6) */
+enum uwb_drp_conflict_action {
+	/* Reservation is mantained, no action needed */
+	UWB_DRP_CONFLICT_MANTAIN = 0,
+	
+	/* the device shall not transmit frames in conflicting MASs in
+	 * the following superframe. If the device is the reservation
+	 * target, it shall also set the Reason Code in its DRP IE to
+	 * Conflict in its beacon in the following superframe.
+	 */
+	UWB_DRP_CONFLICT_ACT1,
+	
+	/* the device shall not set the Reservation Status bit to ONE
+	 * and shall not transmit frames in conflicting MASs. If the
+	 * device is the reservation target, it shall also set the
+	 * Reason Code in its DRP IE to Conflict.
+	 */	
+	UWB_DRP_CONFLICT_ACT2,
+
+	/* the device shall not transmit frames in conflicting MASs in
+	 * the following superframe. It shall remove the conflicting
+	 * MASs from the reservation or set the Reservation Status to
+	 * ZERO in its beacon in the following superframe. If the
+	 * device is the reservation target, it shall also set the
+	 * Reason Code in its DRP IE to Conflict.
+	 */
+	UWB_DRP_CONFLICT_ACT3,
+};
+
+
+static void uwb_rc_set_drp_cmd_done(struct uwb_rc *rc, void *arg,
+				    struct uwb_rceb *reply, ssize_t reply_size)
+{
+	struct uwb_rc_evt_set_drp_ie *r = (struct uwb_rc_evt_set_drp_ie *)reply;
+
+	if (r != NULL) {
+		if (r->bResultCode != UWB_RC_RES_SUCCESS)
+			dev_err(&rc->uwb_dev.dev, "SET-DRP-IE failed: %s (%d)\n",
+				uwb_rc_strerror(r->bResultCode), r->bResultCode);
+	} else
+		dev_err(&rc->uwb_dev.dev, "SET-DRP-IE: timeout\n");
+
+	spin_lock(&rc->rsvs_lock);
+	if (rc->set_drp_ie_pending > 1) {
+		rc->set_drp_ie_pending = 0;
+		uwb_rsv_queue_update(rc);	
+	} else {
+		rc->set_drp_ie_pending = 0;	
+	}
+	spin_unlock(&rc->rsvs_lock);
+}
+
 /**
  * Construct and send the SET DRP IE
  *
···
 int uwb_rc_send_all_drp_ie(struct uwb_rc *rc)
 {
 	int result;
-	struct device *dev = &rc->uwb_dev.dev;
 	struct uwb_rc_cmd_set_drp_ie *cmd;
-	struct uwb_rc_evt_set_drp_ie reply;
 	struct uwb_rsv *rsv;
+	struct uwb_rsv_move *mv;
 	int num_bytes = 0;
 	u8 *IEDataptr;
 
 	result = -ENOMEM;
 	/* First traverse all reservations to determine memory needed. */
 	list_for_each_entry(rsv, &rc->reservations, rc_node) {
-		if (rsv->drp_ie != NULL)
+		if (rsv->drp_ie != NULL) {
 			num_bytes += rsv->drp_ie->hdr.length + 2;
+			if (uwb_rsv_has_two_drp_ies(rsv) &&
+				(rsv->mv.companion_drp_ie != NULL)) {
+				mv = &rsv->mv;
+				num_bytes += mv->companion_drp_ie->hdr.length + 2;	
+			}
+		}
 	}
 	num_bytes += sizeof(rc->drp_avail.ie);
 	cmd = kzalloc(sizeof(*cmd) + num_bytes, GFP_KERNEL);
···
 	cmd->wIELength = num_bytes;
 	IEDataptr = (u8 *)&cmd->IEData[0];
 
+	/* FIXME: DRV avail IE is not always needed */
+	/* put DRP avail IE first */
+	memcpy(IEDataptr, &rc->drp_avail.ie, sizeof(rc->drp_avail.ie));
+	IEDataptr += sizeof(struct uwb_ie_drp_avail);
+
 	/* Next traverse all reservations to place IEs in allocated memory. */
 	list_for_each_entry(rsv, &rc->reservations, rc_node) {
 		if (rsv->drp_ie != NULL) {
 			memcpy(IEDataptr, rsv->drp_ie,
 			       rsv->drp_ie->hdr.length + 2);
 			IEDataptr += rsv->drp_ie->hdr.length + 2;
+			
+			if (uwb_rsv_has_two_drp_ies(rsv) &&
+				(rsv->mv.companion_drp_ie != NULL)) {
+				mv = &rsv->mv;
+				memcpy(IEDataptr, mv->companion_drp_ie,
+				       mv->companion_drp_ie->hdr.length + 2);
+				IEDataptr += mv->companion_drp_ie->hdr.length + 2;	
+			}
 		}
 	}
-	memcpy(IEDataptr, &rc->drp_avail.ie, sizeof(rc->drp_avail.ie));
 
-	reply.rceb.bEventType = UWB_RC_CET_GENERAL;
-	reply.rceb.wEvent = UWB_RC_CMD_SET_DRP_IE;
-	result = uwb_rc_cmd(rc, "SET-DRP-IE", &cmd->rccb,
-			sizeof(*cmd) + num_bytes, &reply.rceb,
-			sizeof(reply));
-	if (result < 0)
-		goto error_cmd;
-	result = le16_to_cpu(reply.wRemainingSpace);
-	if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
-		dev_err(&rc->uwb_dev.dev, "SET-DRP-IE: command execution "
-				"failed: %s (%d). RemainingSpace in beacon "
-				"= %d\n", uwb_rc_strerror(reply.bResultCode),
-				reply.bResultCode, result);
-		result = -EIO;
-	} else {
-		dev_dbg(dev, "SET-DRP-IE sent. RemainingSpace in beacon "
-			     "= %d.\n", result);
-		result = 0;
-	}
-error_cmd:
+	result = uwb_rc_cmd_async(rc, "SET-DRP-IE", &cmd->rccb, sizeof(*cmd) + num_bytes,
+				  UWB_RC_CET_GENERAL, UWB_RC_CMD_SET_DRP_IE,
+				  uwb_rc_set_drp_cmd_done, NULL);
+	
+	rc->set_drp_ie_pending = 1;
+
 	kfree(cmd);
 error:
 	return result;
 }
 
-void uwb_drp_handle_timeout(struct uwb_rsv *rsv)
+/*
+ * Evaluate the action to perform using conflict resolution rules
+ *
+ * Return a uwb_drp_conflict_action.
+ */
+static int evaluate_conflict_action(struct uwb_ie_drp *ext_drp_ie, int ext_beacon_slot,
+				    struct uwb_rsv *rsv, int our_status)
 {
-	struct device *dev = &rsv->rc->uwb_dev.dev;
+	int our_tie_breaker = rsv->tiebreaker;
+	int our_type        = rsv->type;
+	int our_beacon_slot = rsv->rc->uwb_dev.beacon_slot;
 
-	dev_dbg(dev, "reservation timeout in state %s (%d)\n",
-		uwb_rsv_state_str(rsv->state), rsv->state);
-
-	switch (rsv->state) {
-	case UWB_RSV_STATE_O_INITIATED:
-		if (rsv->is_multicast) {
-			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
-			return;
-		}
-		break;
-	case UWB_RSV_STATE_O_ESTABLISHED:
-		if (rsv->is_multicast)
-			return;
-		break;
-	default:
-		break;
+	int ext_tie_breaker = uwb_ie_drp_tiebreaker(ext_drp_ie);
+	int ext_status      = uwb_ie_drp_status(ext_drp_ie);
+	int ext_type        = uwb_ie_drp_type(ext_drp_ie);
+	
+	
+	/* [ECMA-368 2nd Edition] 17.4.6 */
+	if (ext_type == UWB_DRP_TYPE_PCA && our_type == UWB_DRP_TYPE_PCA) {
+		return UWB_DRP_CONFLICT_MANTAIN;
 	}
-	uwb_rsv_remove(rsv);
+
+	/* [ECMA-368 2nd Edition] 17.4.6-1 */
+	if (our_type == UWB_DRP_TYPE_ALIEN_BP) {
+		return UWB_DRP_CONFLICT_MANTAIN;
+	}
+	
+	/* [ECMA-368 2nd Edition] 17.4.6-2 */
+	if (ext_type == UWB_DRP_TYPE_ALIEN_BP) {
+		/* here we know our_type != UWB_DRP_TYPE_ALIEN_BP */
+		return UWB_DRP_CONFLICT_ACT1;
+	}
+
+	/* [ECMA-368 2nd Edition] 17.4.6-3 */
+	if (our_status == 0 && ext_status == 1) {
+		return UWB_DRP_CONFLICT_ACT2;
+	}
+
+	/* [ECMA-368 2nd Edition] 17.4.6-4 */
+	if (our_status == 1 && ext_status == 0) {
+		return UWB_DRP_CONFLICT_MANTAIN;
+	}
+
+	/* [ECMA-368 2nd Edition] 17.4.6-5a */
+	if (our_tie_breaker == ext_tie_breaker &&
+	    our_beacon_slot <  ext_beacon_slot) {
+		return UWB_DRP_CONFLICT_MANTAIN;
+	}
+
+	/* [ECMA-368 2nd Edition] 17.4.6-5b */
+	if (our_tie_breaker != ext_tie_breaker &&
+	    our_beacon_slot >  ext_beacon_slot) {
+		return UWB_DRP_CONFLICT_MANTAIN;
+	}
+	
+	if (our_status == 0) {
+		if (our_tie_breaker == ext_tie_breaker) {
+			/* [ECMA-368 2nd Edition] 17.4.6-6a */
+			if (our_beacon_slot > ext_beacon_slot) {
+				return UWB_DRP_CONFLICT_ACT2;
+			}
+		} else  {
+			/* [ECMA-368 2nd Edition] 17.4.6-6b */
+			if (our_beacon_slot < ext_beacon_slot) {
+				return UWB_DRP_CONFLICT_ACT2;
+			}
+		}
+	} else {
+		if (our_tie_breaker == ext_tie_breaker) {
+			/* [ECMA-368 2nd Edition] 17.4.6-7a */
+			if (our_beacon_slot > ext_beacon_slot) {
+				return UWB_DRP_CONFLICT_ACT3;
+			}
+		} else {
+			/* [ECMA-368 2nd Edition] 17.4.6-7b */
+			if (our_beacon_slot < ext_beacon_slot) {
+				return UWB_DRP_CONFLICT_ACT3;
+			}
+		}
+	}
+	return UWB_DRP_CONFLICT_MANTAIN;
 }
 
+static void handle_conflict_normal(struct uwb_ie_drp *drp_ie, 
+				   int ext_beacon_slot, 
+				   struct uwb_rsv *rsv, 
+				   struct uwb_mas_bm *conflicting_mas)
+{
+	struct uwb_rc *rc = rsv->rc;
+	struct uwb_rsv_move *mv = &rsv->mv;
+	struct uwb_drp_backoff_win *bow = &rc->bow;
+	int action;
+
+	action = evaluate_conflict_action(drp_ie, ext_beacon_slot, rsv, uwb_rsv_status(rsv));
+
+	if (uwb_rsv_is_owner(rsv)) {
+		switch(action) {
+		case UWB_DRP_CONFLICT_ACT2:
+			/* try move */
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_TO_BE_MOVED);
+			if (bow->can_reserve_extra_mases == false)
+				uwb_rsv_backoff_win_increment(rc);
+			
+			break;
+		case UWB_DRP_CONFLICT_ACT3:
+			uwb_rsv_backoff_win_increment(rc);
+			/* drop some mases with reason modified */
+			/* put in the companion the mases to be dropped */
+			bitmap_and(mv->companion_mas.bm, rsv->mas.bm, conflicting_mas->bm, UWB_NUM_MAS);
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MODIFIED);
+		default:
+			break;
+		}
+	} else {
+		switch(action) {
+		case UWB_DRP_CONFLICT_ACT2:
+		case UWB_DRP_CONFLICT_ACT3:
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_CONFLICT);	
+		default:
+			break;
+		}
+
+	}
+	
+}
+
+static void handle_conflict_expanding(struct uwb_ie_drp *drp_ie, int ext_beacon_slot,
+				      struct uwb_rsv *rsv, bool companion_only,
+				      struct uwb_mas_bm *conflicting_mas)
+{
+	struct uwb_rc *rc = rsv->rc;
+	struct uwb_drp_backoff_win *bow = &rc->bow;
+	struct uwb_rsv_move *mv = &rsv->mv;
+	int action;
+	
+	if (companion_only) {
+		/* status of companion is 0 at this point */
+		action = evaluate_conflict_action(drp_ie, ext_beacon_slot, rsv, 0);
+		if (uwb_rsv_is_owner(rsv)) {
+			switch(action) {
+			case UWB_DRP_CONFLICT_ACT2:
+			case UWB_DRP_CONFLICT_ACT3:
+				uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
+				rsv->needs_release_companion_mas = false;
+				if (bow->can_reserve_extra_mases == false)
+					uwb_rsv_backoff_win_increment(rc);
+				uwb_drp_avail_release(rsv->rc, &rsv->mv.companion_mas);
+			}
+		} else { /* rsv is target */			
+			switch(action) {
+			case UWB_DRP_CONFLICT_ACT2:
+			case UWB_DRP_CONFLICT_ACT3:
+				uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_EXPANDING_CONFLICT);
+                                /* send_drp_avail_ie = true; */
+			}
+		}
+	} else { /* also base part of the reservation is conflicting */		
+		if (uwb_rsv_is_owner(rsv)) {
+			uwb_rsv_backoff_win_increment(rc);
+			/* remove companion part */
+			uwb_drp_avail_release(rsv->rc, &rsv->mv.companion_mas);
+
+			/* drop some mases with reason modified */
+
+			/* put in the companion the mases to be dropped */
+			bitmap_andnot(mv->companion_mas.bm, rsv->mas.bm, conflicting_mas->bm, UWB_NUM_MAS);
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MODIFIED);
+		} else { /* it is a target rsv */
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_CONFLICT);
+                        /* send_drp_avail_ie = true; */
+		}
+	}
+}
+
+static void uwb_drp_handle_conflict_rsv(struct uwb_rc *rc, struct uwb_rsv *rsv,
+					struct uwb_rc_evt_drp *drp_evt, 
+					struct uwb_ie_drp *drp_ie,
+					struct uwb_mas_bm *conflicting_mas)
+{
+	struct uwb_rsv_move *mv;
+
+	/* check if the conflicting reservation has two drp_ies */
+	if (uwb_rsv_has_two_drp_ies(rsv)) {
+		mv = &rsv->mv;
+		if (bitmap_intersects(rsv->mas.bm, conflicting_mas->bm, UWB_NUM_MAS)) {
+			handle_conflict_expanding(drp_ie, drp_evt->beacon_slot_number,
+						  rsv, false, conflicting_mas);
+		} else {
+			if (bitmap_intersects(mv->companion_mas.bm, conflicting_mas->bm, UWB_NUM_MAS)) {
+				handle_conflict_expanding(drp_ie, drp_evt->beacon_slot_number,
+							  rsv, true, conflicting_mas);	
+			}
+		}
+	} else if (bitmap_intersects(rsv->mas.bm, conflicting_mas->bm, UWB_NUM_MAS)) {
+		handle_conflict_normal(drp_ie, drp_evt->beacon_slot_number, rsv, conflicting_mas);
+	}
+}
+
+static void uwb_drp_handle_all_conflict_rsv(struct uwb_rc *rc,
+					    struct uwb_rc_evt_drp *drp_evt, 
+					    struct uwb_ie_drp *drp_ie,
+					    struct uwb_mas_bm *conflicting_mas)
+{
+	struct uwb_rsv *rsv;
+	
+	list_for_each_entry(rsv, &rc->reservations, rc_node) {
+		uwb_drp_handle_conflict_rsv(rc, rsv, drp_evt, drp_ie, conflicting_mas);	
+	}
+}
+	
 /*
  * Based on the DRP IE, transition a target reservation to a new
  * state.
  */
 static void uwb_drp_process_target(struct uwb_rc *rc, struct uwb_rsv *rsv,
-				   struct uwb_ie_drp *drp_ie)
+				   struct uwb_ie_drp *drp_ie, struct uwb_rc_evt_drp *drp_evt)
 {
 	struct device *dev = &rc->uwb_dev.dev;
+	struct uwb_rsv_move *mv = &rsv->mv;
 	int status;
 	enum uwb_drp_reason reason_code;
-
+	struct uwb_mas_bm mas;
+	
 	status = uwb_ie_drp_status(drp_ie);
 	reason_code = uwb_ie_drp_reason_code(drp_ie);
+	uwb_drp_ie_to_bm(&mas, drp_ie);
 
-	if (status) {
-		switch (reason_code) {
-		case UWB_DRP_REASON_ACCEPTED:
+	switch (reason_code) {
+	case UWB_DRP_REASON_ACCEPTED:
+
+		if (rsv->state == UWB_RSV_STATE_T_CONFLICT) {
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_CONFLICT);
+			break;
+		}
+
+		if (rsv->state == UWB_RSV_STATE_T_EXPANDING_ACCEPTED) {
+			/* drp_ie is companion */
+			if (!bitmap_equal(rsv->mas.bm, mas.bm, UWB_NUM_MAS))
+				/* stroke companion */
+				uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_EXPANDING_ACCEPTED);	
+		} else {
+			if (!bitmap_equal(rsv->mas.bm, mas.bm, UWB_NUM_MAS)) {
+				if (uwb_drp_avail_reserve_pending(rc, &mas) == -EBUSY) {
+					/* FIXME: there is a conflict, find
+					 * the conflicting reservations and
+					 * take a sensible action. Consider
+					 * that in drp_ie there is the
+					 * "neighbour" */
+					uwb_drp_handle_all_conflict_rsv(rc, drp_evt, drp_ie, &mas);
+				} else {
+					/* accept the extra reservation */
+					bitmap_copy(mv->companion_mas.bm, mas.bm, UWB_NUM_MAS);
+					uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_EXPANDING_ACCEPTED);
+				}
+			} else {
+				if (status) {
+					uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_ACCEPTED);
+				}
+			}
+			
+		}
+		break;
+
+	case UWB_DRP_REASON_MODIFIED:
+		/* check to see if we have already modified the reservation */
+		if (bitmap_equal(rsv->mas.bm, mas.bm, UWB_NUM_MAS)) {
 			uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_ACCEPTED);
 			break;
-		case UWB_DRP_REASON_MODIFIED:
-			dev_err(dev, "FIXME: unhandled reason code (%d/%d)\n",
-				reason_code, status);
-			break;
-		default:
-			dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
-				 reason_code, status);
 		}
-	} else {
-		switch (reason_code) {
-		case UWB_DRP_REASON_ACCEPTED:
-			/* New reservations are handled in uwb_rsv_find(). */
-			break;
-		case UWB_DRP_REASON_DENIED:
-			uwb_rsv_set_state(rsv, UWB_RSV_STATE_NONE);
-			break;
-		case UWB_DRP_REASON_CONFLICT:
-		case UWB_DRP_REASON_MODIFIED:
-			dev_err(dev, "FIXME: unhandled reason code (%d/%d)\n",
-				reason_code, status);
-			break;
-		default:
-			dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
-				 reason_code, status);
+
+		/* find if the owner wants to expand or reduce */
+		if (bitmap_subset(mas.bm, rsv->mas.bm, UWB_NUM_MAS)) {
+			/* owner is reducing */
+			bitmap_andnot(mv->companion_mas.bm, rsv->mas.bm, mas.bm, UWB_NUM_MAS);
+			uwb_drp_avail_release(rsv->rc, &mv->companion_mas);
 		}
+
+		bitmap_copy(rsv->mas.bm, mas.bm, UWB_NUM_MAS);
+		uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_RESIZED);
+		break;
+	default:
+		dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
+			 reason_code, status);
 	}
 }
 
···
  * state.
  */
 static void uwb_drp_process_owner(struct uwb_rc *rc, struct uwb_rsv *rsv,
-				  struct uwb_ie_drp *drp_ie)
+				  struct uwb_dev *src, struct uwb_ie_drp *drp_ie,
+				  struct uwb_rc_evt_drp *drp_evt)
 {
 	struct device *dev = &rc->uwb_dev.dev;
+	struct uwb_rsv_move *mv = &rsv->mv;
 	int status;
 	enum uwb_drp_reason reason_code;
+	struct uwb_mas_bm mas;
 
 	status = uwb_ie_drp_status(drp_ie);
 	reason_code = uwb_ie_drp_reason_code(drp_ie);
+	uwb_drp_ie_to_bm(&mas, drp_ie);
 
 	if (status) {
 		switch (reason_code) {
 		case UWB_DRP_REASON_ACCEPTED:
-			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
-			break;
-		case UWB_DRP_REASON_MODIFIED:
-			dev_err(dev, "FIXME: unhandled reason code (%d/%d)\n",
-				reason_code, status);
+			switch (rsv->state) {
+			case UWB_RSV_STATE_O_PENDING:
+			case UWB_RSV_STATE_O_INITIATED:
+			case UWB_RSV_STATE_O_ESTABLISHED:
+				uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
+				break;
+			case UWB_RSV_STATE_O_MODIFIED:
+				if (bitmap_equal(mas.bm, rsv->mas.bm, UWB_NUM_MAS)) {
+					uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
+				} else {
+					uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MODIFIED);	
+				}
+				break;
+				
+			case UWB_RSV_STATE_O_MOVE_REDUCING: /* shouldn' t be a problem */
+				if (bitmap_equal(mas.bm, rsv->mas.bm, UWB_NUM_MAS)) {
+					uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
+				} else {
+					uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_REDUCING);	
+				}
+				break;
+			case UWB_RSV_STATE_O_MOVE_EXPANDING:
+				if (bitmap_equal(mas.bm, mv->companion_mas.bm, UWB_NUM_MAS)) {
+					/* Companion reservation accepted */
+					uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_COMBINING);
+				} else {
+					uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_EXPANDING);
+				}
+				break;
+			case UWB_RSV_STATE_O_MOVE_COMBINING:
+				if (bitmap_equal(mas.bm, rsv->mas.bm, UWB_NUM_MAS))
+					uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_REDUCING);
+				else
+					uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_COMBINING);
+				break;
+			default:
+				break;	
+			}
 			break;
 		default:
 			dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
···
 			uwb_rsv_set_state(rsv, UWB_RSV_STATE_NONE);
 			break;
 		case UWB_DRP_REASON_CONFLICT:
-		case UWB_DRP_REASON_MODIFIED:
-			dev_err(dev, "FIXME: unhandled reason code (%d/%d)\n",
-				reason_code, status);
+			/* resolve the conflict */
+			bitmap_complement(mas.bm, src->last_availability_bm,
+					  UWB_NUM_MAS);
+			uwb_drp_handle_conflict_rsv(rc, rsv, drp_evt, drp_ie, &mas);
 			break;
 		default:
 			dev_warn(dev, "ignoring invalid DRP IE state (%d/%d)\n",
···
 	}
 }
 
+static void uwb_cnflt_alien_stroke_timer(struct uwb_cnflt_alien *cnflt)
+{
+	unsigned timeout_us = UWB_MAX_LOST_BEACONS * UWB_SUPERFRAME_LENGTH_US;
+	mod_timer(&cnflt->timer, jiffies + usecs_to_jiffies(timeout_us));
+}
+
+static void uwb_cnflt_update_work(struct work_struct *work)
+{
+	struct uwb_cnflt_alien *cnflt = container_of(work,
+						     struct uwb_cnflt_alien,
+						     cnflt_update_work);
+	struct uwb_cnflt_alien *c;
+	struct uwb_rc *rc = cnflt->rc;
+	
+	unsigned long delay_us = UWB_MAS_LENGTH_US * UWB_MAS_PER_ZONE;
+	
+	mutex_lock(&rc->rsvs_mutex);
+
+	list_del(&cnflt->rc_node);
+
+	/* update rc global conflicting alien bitmap */
+	bitmap_zero(rc->cnflt_alien_bitmap.bm, UWB_NUM_MAS);
+
+	list_for_each_entry(c, &rc->cnflt_alien_list, rc_node) {
+		bitmap_or(rc->cnflt_alien_bitmap.bm, rc->cnflt_alien_bitmap.bm, c->mas.bm, UWB_NUM_MAS);			
+	}
+	
+	queue_delayed_work(rc->rsv_workq, &rc->rsv_alien_bp_work, usecs_to_jiffies(delay_us));
+
+	kfree(cnflt);
+	mutex_unlock(&rc->rsvs_mutex);
+}
+
+static void uwb_cnflt_timer(unsigned long arg)
+{
+	struct uwb_cnflt_alien *cnflt = (struct uwb_cnflt_alien *)arg;
+
+	queue_work(cnflt->rc->rsv_workq, &cnflt->cnflt_update_work);
+}
+
 /*
- * Process a received DRP IE, it's either for a reservation owned by
- * the RC or targeted at it (or it's for a WUSB cluster reservation).
+ * We have received an DRP_IE of type Alien BP and we need to make
+ * sure we do not transmit in conflicting MASs.
  */
-static void uwb_drp_process(struct uwb_rc *rc, struct uwb_dev *src,
-		     struct uwb_ie_drp *drp_ie)
+static void uwb_drp_handle_alien_drp(struct uwb_rc *rc, struct uwb_ie_drp *drp_ie)
+{
+	struct device *dev = &rc->uwb_dev.dev;
+	struct uwb_mas_bm mas;
+	struct uwb_cnflt_alien *cnflt;
+	char buf[72];
+	unsigned long delay_us = UWB_MAS_LENGTH_US * UWB_MAS_PER_ZONE;
+	
+	uwb_drp_ie_to_bm(&mas, drp_ie);
+	bitmap_scnprintf(buf, sizeof(buf), mas.bm, UWB_NUM_MAS);
+	
+	list_for_each_entry(cnflt, &rc->cnflt_alien_list, rc_node) {
+		if (bitmap_equal(cnflt->mas.bm, mas.bm, UWB_NUM_MAS)) {
+			/* Existing alien BP reservation conflicting
+			 * bitmap, just reset the timer */
+			uwb_cnflt_alien_stroke_timer(cnflt);
+			return;
+		}
+	}
+
+	/* New alien BP reservation conflicting bitmap */
+
+	/* alloc and initialize new uwb_cnflt_alien */
+	cnflt = kzalloc(sizeof(struct uwb_cnflt_alien), GFP_KERNEL);
+	if (!cnflt)
+		dev_err(dev, "failed to alloc uwb_cnflt_alien struct\n");
+	INIT_LIST_HEAD(&cnflt->rc_node);
+	init_timer(&cnflt->timer);
+	cnflt->timer.function = uwb_cnflt_timer;
+	cnflt->timer.data     = (unsigned long)cnflt;
+
+	cnflt->rc = rc;
+	INIT_WORK(&cnflt->cnflt_update_work, uwb_cnflt_update_work);
+	
+	bitmap_copy(cnflt->mas.bm, mas.bm, UWB_NUM_MAS);
+
+	list_add_tail(&cnflt->rc_node, &rc->cnflt_alien_list);
+
+	/* update rc global conflicting alien bitmap */
+	bitmap_or(rc->cnflt_alien_bitmap.bm, rc->cnflt_alien_bitmap.bm, mas.bm, UWB_NUM_MAS);
+
+	queue_delayed_work(rc->rsv_workq, &rc->rsv_alien_bp_work, usecs_to_jiffies(delay_us));
+	
+	/* start the timer */
+	uwb_cnflt_alien_stroke_timer(cnflt);
+}
+
+static void uwb_drp_process_not_involved(struct uwb_rc *rc,
+					 struct uwb_rc_evt_drp *drp_evt, 
+					 struct uwb_ie_drp *drp_ie)
+{
+	struct uwb_mas_bm mas;
+	
+	uwb_drp_ie_to_bm(&mas, drp_ie);
+	uwb_drp_handle_all_conflict_rsv(rc, drp_evt, drp_ie, &mas);
+}
+
+static void uwb_drp_process_involved(struct uwb_rc *rc, struct uwb_dev *src,
+				     struct uwb_rc_evt_drp *drp_evt,
+				     struct uwb_ie_drp *drp_ie)
 {
 	struct uwb_rsv *rsv;
 
···
 		 */
 		return;
 	}
-
+	
 	/*
 	 * Do nothing with DRP IEs for reservations that have been
 	 * terminated.
···
 		uwb_rsv_set_state(rsv, UWB_RSV_STATE_NONE);
 		return;
 	}
-
+			
 	if (uwb_ie_drp_owner(drp_ie))
-		uwb_drp_process_target(rc, rsv, drp_ie);
+		uwb_drp_process_target(rc, rsv, drp_ie, drp_evt);
 	else
-		uwb_drp_process_owner(rc, rsv, drp_ie);
+		uwb_drp_process_owner(rc, rsv, src, drp_ie, drp_evt);
+	
 }
 
+
+static bool uwb_drp_involves_us(struct uwb_rc *rc, struct uwb_ie_drp *drp_ie)
+{
+	return uwb_dev_addr_cmp(&rc->uwb_dev.dev_addr, &drp_ie->dev_addr) == 0;
+}
+
+/*
+ * Process a received DRP IE.
+ */
+static void uwb_drp_process(struct uwb_rc *rc, struct uwb_rc_evt_drp *drp_evt,
+			    struct uwb_dev *src, struct uwb_ie_drp *drp_ie)
+{
+	if (uwb_ie_drp_type(drp_ie) == UWB_DRP_TYPE_ALIEN_BP)
+		uwb_drp_handle_alien_drp(rc, drp_ie);
+	else if (uwb_drp_involves_us(rc, drp_ie))
+		uwb_drp_process_involved(rc, src, drp_evt, drp_ie);
+	else
+		uwb_drp_process_not_involved(rc, drp_evt, drp_ie);
+}
+
+/*
+ * Process a received DRP Availability IE
+ */
+static void uwb_drp_availability_process(struct uwb_rc *rc, struct uwb_dev *src,
+					 struct uwb_ie_drp_avail *drp_availability_ie)
+{
+	bitmap_copy(src->last_availability_bm,
+		    drp_availability_ie->bmp, UWB_NUM_MAS);
+}
 
 /*
  * Process all the DRP IEs (both DRP IEs and the DRP Availability IE)
···
 
 		switch (ie_hdr->element_id) {
 		case UWB_IE_DRP_AVAILABILITY:
-			/* FIXME: does something need to be done with this? */
+			uwb_drp_availability_process(rc, src_dev, (struct uwb_ie_drp_avail *)ie_hdr);
 			break;
 		case UWB_IE_DRP:
-			uwb_drp_process(rc, src_dev, (struct uwb_ie_drp *)ie_hdr);
+			uwb_drp_process(rc, drp_evt, src_dev, (struct uwb_ie_drp *)ie_hdr);
 			break;
 		default:
 			dev_warn(dev, "unexpected IE in DRP notification\n");
···
 		dev_warn(dev, "%d octets remaining in DRP notification\n",
 			 (int)ielen);
 }
-
-
-/*
- * Go through all the DRP IEs and find the ones that conflict with our
- * reservations.
- *
- * FIXME: must resolve the conflict according the the rules in
- * [ECMA-368].
- */
-static
-void uwb_drp_process_conflict_all(struct uwb_rc *rc, struct uwb_rc_evt_drp *drp_evt,
-				  size_t ielen, struct uwb_dev *src_dev)
-{
-	struct device *dev = &rc->uwb_dev.dev;
-	struct uwb_ie_hdr *ie_hdr;
-	struct uwb_ie_drp *drp_ie;
-	void *ptr;
-
-	ptr = drp_evt->ie_data;
-	for (;;) {
-		ie_hdr = uwb_ie_next(&ptr, &ielen);
-		if (!ie_hdr)
-			break;
-
-		drp_ie = container_of(ie_hdr, struct uwb_ie_drp, hdr);
-
-		/* FIXME: check if this DRP IE conflicts. */
-	}
-
-	if (ielen > 0)
-		dev_warn(dev, "%d octets remaining in DRP notification\n",
-			 (int)ielen);
-}
-
-
-/*
- * Terminate all reservations owned by, or targeted at, 'uwb_dev'.
- */
-static void uwb_drp_terminate_all(struct uwb_rc *rc, struct uwb_dev *uwb_dev)
-{
-	struct uwb_rsv *rsv;
-
-	list_for_each_entry(rsv, &rc->reservations, rc_node) {
-		if (rsv->owner == uwb_dev
-		    || (rsv->target.type == UWB_RSV_TARGET_DEV && rsv->target.dev == uwb_dev))
-			uwb_rsv_remove(rsv);
-	}
-}
-
 
 /**
  * uwbd_evt_handle_rc_drp - handle a DRP_IE event
···
 	size_t ielength, bytes_left;
 	struct uwb_dev_addr src_addr;
 	struct uwb_dev *src_dev;
-	int reason;
 
 	/* Is there enough data to decode the event (and any IEs in
 	   its payload)? */
···
 
 	mutex_lock(&rc->rsvs_mutex);
 
-	reason = uwb_rc_evt_drp_reason(drp_evt);
-
-	switch (reason) {
-	case UWB_DRP_NOTIF_DRP_IE_RCVD:
-		uwb_drp_process_all(rc, drp_evt, ielength, src_dev);
-		break;
-	case UWB_DRP_NOTIF_CONFLICT:
-		uwb_drp_process_conflict_all(rc, drp_evt, ielength, src_dev);
-		break;
-	case UWB_DRP_NOTIF_TERMINATE:
-		uwb_drp_terminate_all(rc, src_dev);
-		break;
-	default:
-		dev_warn(dev, "ignored DRP event with reason code: %d\n", reason);
-		break;
-	}
+	/* We do not distinguish from the reason */
+	uwb_drp_process_all(rc, drp_evt, ielength, src_dev);
 
 	mutex_unlock(&rc->rsvs_mutex);
 

drivers/uwb/rsv.c

···
  */
 #include <linux/kernel.h>
 #include <linux/uwb.h>
+#include <linux/random.h>
 
 #include "uwb-internal.h"
 
 static void uwb_rsv_timer(unsigned long arg);
 
 static const char *rsv_states[] = {
-	[UWB_RSV_STATE_NONE]          = "none",
-	[UWB_RSV_STATE_O_INITIATED]   = "initiated",
-	[UWB_RSV_STATE_O_PENDING]     = "pending",
-	[UWB_RSV_STATE_O_MODIFIED]    = "modified",
-	[UWB_RSV_STATE_O_ESTABLISHED] = "established",
-	[UWB_RSV_STATE_T_ACCEPTED]    = "accepted",
-	[UWB_RSV_STATE_T_DENIED]      = "denied",
-	[UWB_RSV_STATE_T_PENDING]     = "pending",
+	[UWB_RSV_STATE_NONE]                 = "none            ",
+	[UWB_RSV_STATE_O_INITIATED]          = "o initiated     ",
+	[UWB_RSV_STATE_O_PENDING]            = "o pending       ",
+	[UWB_RSV_STATE_O_MODIFIED]           = "o modified      ",
+	[UWB_RSV_STATE_O_ESTABLISHED]        = "o established   ",
+	[UWB_RSV_STATE_O_TO_BE_MOVED]        = "o to be moved   ",
+	[UWB_RSV_STATE_O_MOVE_EXPANDING]     = "o move expanding",
+	[UWB_RSV_STATE_O_MOVE_COMBINING]     = "o move combining",
+	[UWB_RSV_STATE_O_MOVE_REDUCING]      = "o move reducing ",
+	[UWB_RSV_STATE_T_ACCEPTED]           = "t accepted      ",
+	[UWB_RSV_STATE_T_CONFLICT]           = "t conflict      ",
+	[UWB_RSV_STATE_T_PENDING]            = "t pending       ",
+	[UWB_RSV_STATE_T_DENIED]             = "t denied        ",
+	[UWB_RSV_STATE_T_RESIZED]            = "t resized       ",
+	[UWB_RSV_STATE_T_EXPANDING_ACCEPTED] = "t expanding acc ",
+	[UWB_RSV_STATE_T_EXPANDING_CONFLICT] = "t expanding conf",
+	[UWB_RSV_STATE_T_EXPANDING_PENDING]  = "t expanding pend",
+	[UWB_RSV_STATE_T_EXPANDING_DENIED]   = "t expanding den ",
 };
 
 static const char *rsv_types[] = {
···
 	[UWB_DRP_TYPE_PRIVATE]  = "private",
 	[UWB_DRP_TYPE_PCA]      = "pca",
 };
+
+bool uwb_rsv_has_two_drp_ies(struct uwb_rsv *rsv)
+{
+	static const bool has_two_drp_ies[] = {
+		[UWB_RSV_STATE_O_INITIATED]               = false,
+		[UWB_RSV_STATE_O_PENDING]                 = false,
+		[UWB_RSV_STATE_O_MODIFIED]                = false,
+		[UWB_RSV_STATE_O_ESTABLISHED]             = false,
+		[UWB_RSV_STATE_O_TO_BE_MOVED]             = false,
+		[UWB_RSV_STATE_O_MOVE_COMBINING]          = false,
+		[UWB_RSV_STATE_O_MOVE_REDUCING]           = false,
+		[UWB_RSV_STATE_O_MOVE_EXPANDING]          = true,
+		[UWB_RSV_STATE_T_ACCEPTED]                = false,
+		[UWB_RSV_STATE_T_CONFLICT]                = false,
+		[UWB_RSV_STATE_T_PENDING]                 = false,
+		[UWB_RSV_STATE_T_DENIED]                  = false,
+		[UWB_RSV_STATE_T_RESIZED]                 = false,
+		[UWB_RSV_STATE_T_EXPANDING_ACCEPTED]      = true,
+		[UWB_RSV_STATE_T_EXPANDING_CONFLICT]      = true,
+		[UWB_RSV_STATE_T_EXPANDING_PENDING]       = true,
+		[UWB_RSV_STATE_T_EXPANDING_DENIED]        = true,
+	};
+
+	return has_two_drp_ies[rsv->state];
+}
 
 /**
  * uwb_rsv_state_str - return a string for a reservation state
···
 }
 EXPORT_SYMBOL_GPL(uwb_rsv_type_str);
 
-static void uwb_rsv_dump(struct uwb_rsv *rsv)
+void uwb_rsv_dump(char *text, struct uwb_rsv *rsv)
 {
 	struct device *dev = &rsv->rc->uwb_dev.dev;
 	struct uwb_dev_addr devaddr;
···
 	kfree(rsv);
 }
 
-static void uwb_rsv_get(struct uwb_rsv *rsv)
+void uwb_rsv_get(struct uwb_rsv *rsv)
 {
 	kref_get(&rsv->kref);
 }
 
-static void uwb_rsv_put(struct uwb_rsv *rsv)
+void uwb_rsv_put(struct uwb_rsv *rsv)
 {
 	kref_put(&rsv->kref, uwb_rsv_release);
 }
···
 static int uwb_rsv_get_stream(struct uwb_rsv *rsv)
 {
 	struct uwb_rc *rc = rsv->rc;
+	struct device *dev = &rc->uwb_dev.dev;
 	unsigned long *streams_bm;
 	int stream;
 
···
 	rsv->stream = stream;
 	set_bit(stream, streams_bm);
 
+	dev_dbg(dev, "get stream %d\n", rsv->stream);
+
 	return 0;
 }
 
 static void uwb_rsv_put_stream(struct uwb_rsv *rsv)
 {
 	struct uwb_rc *rc = rsv->rc;
+	struct device *dev = &rc->uwb_dev.dev;
 	unsigned long *streams_bm;
 
 	switch (rsv->target.type) {
···
 	}
 
 	clear_bit(rsv->stream, streams_bm);
+
+	dev_dbg(dev, "put stream %d\n", rsv->stream);
 }
 
-/*
- * Generate a MAS allocation with a single row component.
- */
-static void uwb_rsv_gen_alloc_row(struct uwb_mas_bm *mas,
-				  int first_mas, int mas_per_zone,
-				  int zs, int ze)
+void uwb_rsv_backoff_win_timer(unsigned long arg)
 {
-	struct uwb_mas_bm col;
-	int z;
+	struct uwb_drp_backoff_win *bow = (struct uwb_drp_backoff_win *)arg;
+	struct uwb_rc *rc = container_of(bow, struct uwb_rc, bow);
+	struct device *dev = &rc->uwb_dev.dev;
 
-	bitmap_zero(mas->bm, UWB_NUM_MAS);
-	bitmap_zero(col.bm, UWB_NUM_MAS);
-	bitmap_fill(col.bm, mas_per_zone);
-	bitmap_shift_left(col.bm, col.bm, first_mas + zs * UWB_MAS_PER_ZONE, UWB_NUM_MAS);
-
-	for (z = zs; z <= ze; z++) {
-		bitmap_or(mas->bm, mas->bm, col.bm, UWB_NUM_MAS);
-		bitmap_shift_left(col.bm, col.bm, UWB_MAS_PER_ZONE, UWB_NUM_MAS);
+	bow->can_reserve_extra_mases = true;
+	if (bow->total_expired <= 4) {
+		bow->total_expired++;
+	} else {
+		/* after 4 backoff window has expired we can exit from
+		 * the backoff procedure */
+		bow->total_expired = 0;
+		bow->window = UWB_DRP_BACKOFF_WIN_MIN >> 1;
 	}
+	dev_dbg(dev, "backoff_win_timer total_expired=%d, n=%d\n: ", bow->total_expired, bow->n);
+
+	/* try to relocate all the "to be moved" relocations */
+	uwb_rsv_handle_drp_avail_change(rc);
 }
 
-/*
- * Allocate some MAS for this reservation based on current local
- * availability, the reservation parameters (max_mas, min_mas,
- * sparsity), and the WiMedia rules for MAS allocations.
- *
- * Returns -EBUSY is insufficient free MAS are available.
- *
- * FIXME: to simplify this, only safe reservations with a single row
- * component in zones 1 to 15 are tried (zone 0 is skipped to avoid
- * problems with the MAS reserved for the BP).
- *
- * [ECMA-368] section B.2.
- */
-static int uwb_rsv_alloc_mas(struct uwb_rsv *rsv)
+void uwb_rsv_backoff_win_increment(struct uwb_rc *rc)
 {
-	static const int safe_mas_in_row[UWB_NUM_ZONES] = {
-		8, 7, 6, 5, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 2, 1,
-	};
-	int n, r;
-	struct uwb_mas_bm mas;
-	bool found = false;
+	struct uwb_drp_backoff_win *bow = &rc->bow;
+	struct device *dev = &rc->uwb_dev.dev;
+	unsigned timeout_us;
 
-	/*
-	 * Search all valid safe allocations until either: too few MAS
-	 * are available; or the smallest allocation with sufficient
-	 * MAS is found.
-	 *
-	 * The top of the zones are preferred, so space for larger
-	 * allocations is available in the bottom of the zone (e.g., a
-	 * 15 MAS allocation should start in row 14 leaving space for
-	 * a 120 MAS allocation at row 0).
-	 */
-	for (n = safe_mas_in_row[0]; n >= 1; n--) {
-		int num_mas;
+	dev_dbg(dev, "backoff_win_increment: window=%d\n", bow->window);
 
-		num_mas = n * (UWB_NUM_ZONES - 1);
-		if (num_mas < rsv->min_mas)
-			break;
-		if (found && num_mas < rsv->max_mas)
-			break;
+	bow->can_reserve_extra_mases = false;
 
-		for (r = UWB_MAS_PER_ZONE-1;  r >= 0; r--) {
-			if (safe_mas_in_row[r] < n)
-				continue;
-			uwb_rsv_gen_alloc_row(&mas, r, n, 1, UWB_NUM_ZONES);
-			if (uwb_drp_avail_reserve_pending(rsv->rc, &mas) == 0) {
-				found = true;
-				break;
-			}
-		}
-	}
+	if((bow->window << 1) == UWB_DRP_BACKOFF_WIN_MAX)
+		return;
 
-	if (!found)
-		return -EBUSY;
+	bow->window <<= 1;
+	bow->n = random32() & (bow->window - 1);
+	dev_dbg(dev, "new_window=%d, n=%d\n: ", bow->window, bow->n);
 
-	bitmap_copy(rsv->mas.bm, mas.bm, UWB_NUM_MAS);
-	return 0;
+	/* reset the timer associated variables */
+	timeout_us = bow->n * UWB_SUPERFRAME_LENGTH_US;
+	bow->total_expired = 0;
+	mod_timer(&bow->timer, jiffies + usecs_to_jiffies(timeout_us));		
 }
 
 static void uwb_rsv_stroke_timer(struct uwb_rsv *rsv)
···
 	 * received.
 	 */
 	if (rsv->is_multicast) {
-		if (rsv->state == UWB_RSV_STATE_O_INITIATED)
+		if (rsv->state == UWB_RSV_STATE_O_INITIATED
+		    || rsv->state == UWB_RSV_STATE_O_MOVE_EXPANDING
+		    || rsv->state == UWB_RSV_STATE_O_MOVE_COMBINING
+		    || rsv->state == UWB_RSV_STATE_O_MOVE_REDUCING)
 			sframes = 1;
 		if (rsv->state == UWB_RSV_STATE_O_ESTABLISHED)
 			sframes = 0;
+		
 	}
 
-	rsv->expired = false;
 	if (sframes > 0) {
 		/*
 		 * Add an additional 2 superframes to account for the
···
 	rsv->state = new_state;
 	rsv->ie_valid = false;
 
-	uwb_rsv_dump(rsv);
+	uwb_rsv_dump("SU", rsv);
 
 	uwb_rsv_stroke_timer(rsv);
 	uwb_rsv_sched_update(rsv->rc);
···
 
 void uwb_rsv_set_state(struct uwb_rsv *rsv, enum uwb_rsv_state new_state)
 {
+	struct uwb_rsv_move *mv = &rsv->mv;
+
 	if (rsv->state == new_state) {
 		switch (rsv->state) {
 		case UWB_RSV_STATE_O_ESTABLISHED:
+		case UWB_RSV_STATE_O_MOVE_EXPANDING:
+		case UWB_RSV_STATE_O_MOVE_COMBINING:
+		case UWB_RSV_STATE_O_MOVE_REDUCING:
 		case UWB_RSV_STATE_T_ACCEPTED:
+		case UWB_RSV_STATE_T_EXPANDING_ACCEPTED:
+		case UWB_RSV_STATE_T_RESIZED:
 		case UWB_RSV_STATE_NONE:
 			uwb_rsv_stroke_timer(rsv);
 			break;
···
 		return;
 	}
 
+	uwb_rsv_dump("SC", rsv);
+
 	switch (new_state) {
 	case UWB_RSV_STATE_NONE:
-		uwb_drp_avail_release(rsv->rc, &rsv->mas);
-		if (uwb_rsv_is_owner(rsv))
-			uwb_rsv_put_stream(rsv);
 		uwb_rsv_state_update(rsv, UWB_RSV_STATE_NONE);
 		uwb_rsv_callback(rsv);
 		break;
···
 	case UWB_RSV_STATE_O_PENDING:
 		uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_PENDING);
 		break;
+	case UWB_RSV_STATE_O_MODIFIED:
+		/* in the companion there are the MASes to drop */
+		bitmap_andnot(rsv->mas.bm, rsv->mas.bm, mv->companion_mas.bm, UWB_NUM_MAS);
+		uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_MODIFIED);
+		break;
 	case UWB_RSV_STATE_O_ESTABLISHED:
+		if (rsv->state == UWB_RSV_STATE_O_MODIFIED
+		    || rsv->state == UWB_RSV_STATE_O_MOVE_REDUCING) {
+			uwb_drp_avail_release(rsv->rc, &mv->companion_mas);
+			rsv->needs_release_companion_mas = false;
+		}
 		uwb_drp_avail_reserve(rsv->rc, &rsv->mas);
 		uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_ESTABLISHED);
 		uwb_rsv_callback(rsv);
 		break;
+	case UWB_RSV_STATE_O_MOVE_EXPANDING:
+		rsv->needs_release_companion_mas = true;
+		uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_MOVE_EXPANDING);
+		break;
+	case UWB_RSV_STATE_O_MOVE_COMBINING:
+		rsv->needs_release_companion_mas = false;
+		uwb_drp_avail_reserve(rsv->rc, &mv->companion_mas);
+		bitmap_or(rsv->mas.bm, rsv->mas.bm, mv->companion_mas.bm, UWB_NUM_MAS);
+		rsv->mas.safe   += mv->companion_mas.safe;
+		rsv->mas.unsafe += mv->companion_mas.unsafe;
+		uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_MOVE_COMBINING);
+		break;
+	case UWB_RSV_STATE_O_MOVE_REDUCING:
+		bitmap_andnot(mv->companion_mas.bm, rsv->mas.bm, mv->final_mas.bm, UWB_NUM_MAS);
+		rsv->needs_release_companion_mas = true;
+		rsv->mas.safe   = mv->final_mas.safe;
+		rsv->mas.unsafe = mv->final_mas.unsafe;
+		bitmap_copy(rsv->mas.bm, mv->final_mas.bm, UWB_NUM_MAS);
+		bitmap_copy(rsv->mas.unsafe_bm, mv->final_mas.unsafe_bm, UWB_NUM_MAS);
+		uwb_rsv_state_update(rsv, UWB_RSV_STATE_O_MOVE_REDUCING);
+		break;
 	case UWB_RSV_STATE_T_ACCEPTED:
+	case UWB_RSV_STATE_T_RESIZED:
+		rsv->needs_release_companion_mas = false;
 		uwb_drp_avail_reserve(rsv->rc, &rsv->mas);
 		uwb_rsv_state_update(rsv, UWB_RSV_STATE_T_ACCEPTED);
 		uwb_rsv_callback(rsv);
···
 	case UWB_RSV_STATE_T_DENIED:
 		uwb_rsv_state_update(rsv, UWB_RSV_STATE_T_DENIED);
 		break;
+	case UWB_RSV_STATE_T_CONFLICT:
+		uwb_rsv_state_update(rsv, UWB_RSV_STATE_T_CONFLICT);
+		break;
+	case UWB_RSV_STATE_T_PENDING:
+		uwb_rsv_state_update(rsv, UWB_RSV_STATE_T_PENDING);
+		break;
+	case UWB_RSV_STATE_T_EXPANDING_ACCEPTED:
+		rsv->needs_release_companion_mas = true;
+		uwb_drp_avail_reserve(rsv->rc, &mv->companion_mas);
+		uwb_rsv_state_update(rsv, UWB_RSV_STATE_T_EXPANDING_ACCEPTED);
+		break;
 	default:
 		dev_err(&rsv->rc->uwb_dev.dev, "unhandled state: %s (%d)\n",
 			uwb_rsv_state_str(new_state), new_state);
 	}
+}
+
+static void uwb_rsv_handle_timeout_work(struct work_struct *work)
+{
+	struct uwb_rsv *rsv = container_of(work, struct uwb_rsv,
+					   handle_timeout_work);
+	struct uwb_rc *rc = rsv->rc;
+
+	mutex_lock(&rc->rsvs_mutex);
+
+	uwb_rsv_dump("TO", rsv);
+
+	switch (rsv->state) {
+	case UWB_RSV_STATE_O_INITIATED:
+		if (rsv->is_multicast) {
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
+			goto unlock;
+		}
+		break;
+	case UWB_RSV_STATE_O_MOVE_EXPANDING:
+		if (rsv->is_multicast) {
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_COMBINING);
+			goto unlock;
+		}
+		break;
+	case UWB_RSV_STATE_O_MOVE_COMBINING:
+		if (rsv->is_multicast) {
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_REDUCING);
+			goto unlock;
+		}
+		break;
+	case UWB_RSV_STATE_O_MOVE_REDUCING:
+		if (rsv->is_multicast) {
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_ESTABLISHED);
+			goto unlock;
+		}
+		break;
+	case UWB_RSV_STATE_O_ESTABLISHED:
+		if (rsv->is_multicast)
+			goto unlock;
+		break;
+	case UWB_RSV_STATE_T_EXPANDING_ACCEPTED:
+		/*
+		 * The time out could be for the main or of the
+		 * companion DRP, assume it's for the companion and
+		 * drop that first.  A further time out is required to
+		 * drop the main.
+		 */
+		uwb_rsv_set_state(rsv, UWB_RSV_STATE_T_ACCEPTED);
+		uwb_drp_avail_release(rsv->rc, &rsv->mv.companion_mas);
+		goto unlock;
+	default:
+		break;
+	}
+
+	uwb_rsv_remove(rsv);
+
+unlock:
+	mutex_unlock(&rc->rsvs_mutex);
 }
 
 static struct uwb_rsv *uwb_rsv_alloc(struct uwb_rc *rc)
···
 	rsv->timer.data     = (unsigned long)rsv;
 
 	rsv->rc = rc;
+	INIT_WORK(&rsv->handle_timeout_work, uwb_rsv_handle_timeout_work);
 
 	return rsv;
 }
···
 
 void uwb_rsv_remove(struct uwb_rsv *rsv)
 {
+	uwb_rsv_dump("RM", rsv);
+
 	if (rsv->state != UWB_RSV_STATE_NONE)
 		uwb_rsv_set_state(rsv, UWB_RSV_STATE_NONE);
+
+	if (rsv->needs_release_companion_mas)
+		uwb_drp_avail_release(rsv->rc, &rsv->mv.companion_mas);
+	uwb_drp_avail_release(rsv->rc, &rsv->mas);
+
+	if (uwb_rsv_is_owner(rsv))
+		uwb_rsv_put_stream(rsv);
+	
 	del_timer_sync(&rsv->timer);
 	uwb_dev_put(rsv->owner);
 	if (rsv->target.type == UWB_RSV_TARGET_DEV)
···
  * @rsv: the reservation
  *
  * The PAL should fill in @rsv's owner, target, type, max_mas,
- * min_mas, sparsity and is_multicast fields.  If the target is a
+ * min_mas, max_interval and is_multicast fields.  If the target is a
  * uwb_dev it must be referenced.
  *
  * The reservation's callback will be called when the reservation is
···
 int uwb_rsv_establish(struct uwb_rsv *rsv)
 {
 	struct uwb_rc *rc = rsv->rc;
+	struct uwb_mas_bm available;
 	int ret;
 
 	mutex_lock(&rc->rsvs_mutex);
-
 	ret = uwb_rsv_get_stream(rsv);
 	if (ret)
 		goto out;
 
-	ret = uwb_rsv_alloc_mas(rsv);
-	if (ret) {
+	rsv->tiebreaker = random32() & 1;
+	/* get available mas bitmap */
+	uwb_drp_available(rc, &available);
+
+	ret = uwb_rsv_find_best_allocation(rsv, &available, &rsv->mas);
+	if (ret == UWB_RSV_ALLOC_NOT_FOUND) {
+		ret = -EBUSY;
+		uwb_rsv_put_stream(rsv);
+		goto out;
+	}
+
+	ret = uwb_drp_avail_reserve_pending(rc, &rsv->mas);
+	if (ret != 0) {
 		uwb_rsv_put_stream(rsv);
 		goto out;
 	}
···
  * @rsv: the reservation to modify
  * @max_mas: new maximum MAS to reserve
  * @min_mas: new minimum MAS to reserve
- * @sparsity: new sparsity to use
+ * @max_interval: new max_interval to use
  *
  * FIXME: implement this once there are PALs that use it.
  */
-int uwb_rsv_modify(struct uwb_rsv *rsv, int max_mas, int min_mas, int sparsity)
+int uwb_rsv_modify(struct uwb_rsv *rsv, int max_mas, int min_mas, int max_interval)
 {
 	return -ENOSYS;
 }
 EXPORT_SYMBOL_GPL(uwb_rsv_modify);
+
+/*
+ * move an already established reservation (rc->rsvs_mutex must to be
+ * taken when tis function is called)
+ */
+int uwb_rsv_try_move(struct uwb_rsv *rsv, struct uwb_mas_bm *available)
+{
+	struct uwb_rc *rc = rsv->rc;
+	struct uwb_drp_backoff_win *bow = &rc->bow;
+	struct device *dev = &rc->uwb_dev.dev;
+	struct uwb_rsv_move *mv;
+	int ret = 0;
+ 
+	if (bow->can_reserve_extra_mases == false)
+		return -EBUSY;
+
+	mv = &rsv->mv;
+
+	if (uwb_rsv_find_best_allocation(rsv, available, &mv->final_mas) == UWB_RSV_ALLOC_FOUND) {
+
+		if (!bitmap_equal(rsv->mas.bm, mv->final_mas.bm, UWB_NUM_MAS)) {
+			/* We want to move the reservation */
+			bitmap_andnot(mv->companion_mas.bm, mv->final_mas.bm, rsv->mas.bm, UWB_NUM_MAS);
+			uwb_drp_avail_reserve_pending(rc, &mv->companion_mas);
+			uwb_rsv_set_state(rsv, UWB_RSV_STATE_O_MOVE_EXPANDING);
+		}
+	} else {
+		dev_dbg(dev, "new allocation not found\n");
+	}
+	
+	return ret;
+}
+
+/* It will try to move every reservation in state O_ESTABLISHED giving
+ * to the MAS allocator algorithm an availability that is the real one
+ * plus the allocation already established from the reservation. */
+void uwb_rsv_handle_drp_avail_change(struct uwb_rc *rc)
+{
+	struct uwb_drp_backoff_win *bow = &rc->bow;
+	struct uwb_rsv *rsv;
+	struct uwb_mas_bm mas;
+	
+	if (bow->can_reserve_extra_mases == false)
+		return;
+
+	list_for_each_entry(rsv, &rc->reservations, rc_node) {
+		if (rsv->state == UWB_RSV_STATE_O_ESTABLISHED ||
+		    rsv->state == UWB_RSV_STATE_O_TO_BE_MOVED) {
+			uwb_drp_available(rc, &mas);
+			bitmap_or(mas.bm, mas.bm, rsv->mas.bm, UWB_NUM_MAS);
+			uwb_rsv_try_move(rsv, &mas);
+		}
+	}
+	
+}
 
 /**
  * uwb_rsv_terminate - terminate an established reservation
···
 	uwb_dev_get(rsv->owner);
 	rsv->target.type = UWB_RSV_TARGET_DEV;
 	rsv->target.dev  = &rc->uwb_dev;
+	uwb_dev_get(&rc->uwb_dev);
 	rsv->type        = uwb_ie_drp_type(drp_ie);
 	rsv->stream      = uwb_ie_drp_stream_index(drp_ie);
 	uwb_drp_ie_to_bm(&rsv->mas, drp_ie);
···
 	list_add_tail(&rsv->rc_node, &rc->reservations);
 	state = rsv->state;
 	rsv->state = UWB_RSV_STATE_NONE;
-	uwb_rsv_set_state(rsv, state);
+
+	/* FIXME: do something sensible here */
+	if (state == UWB_RSV_STATE_T_ACCEPTED
+	    && uwb_drp_avail_reserve_pending(rc, &rsv->mas) == -EBUSY) {
+		/* FIXME: do something sensible here */
+	} else {
+		uwb_rsv_set_state(rsv, state);
+	}
 
 	return rsv;
 }
+
+/**
+ * uwb_rsv_get_usable_mas - get the bitmap of the usable MAS of a reservations
+ * @rsv: the reservation.
+ * @mas: returns the available MAS.
+ *
+ * The usable MAS of a reservation may be less than the negotiated MAS
+ * if alien BPs are present.
+ */
+void uwb_rsv_get_usable_mas(struct uwb_rsv *rsv, struct uwb_mas_bm *mas)
+{
+	bitmap_zero(mas->bm, UWB_NUM_MAS);
+	bitmap_andnot(mas->bm, rsv->mas.bm, rsv->rc->cnflt_alien_bitmap.bm, UWB_NUM_MAS);
+}
+EXPORT_SYMBOL_GPL(uwb_rsv_get_usable_mas);
 
 /**
  * uwb_rsv_find - find a reservation for a received DRP IE.
···
 	bool ie_updated = false;
 
 	list_for_each_entry_safe(rsv, t, &rc->reservations, rc_node) {
-		if (rsv->expired)
-			uwb_drp_handle_timeout(rsv);
 		if (!rsv->ie_valid) {
 			uwb_drp_ie_update(rsv);
 			ie_updated = true;
···
 	return ie_updated;
 }
 
+void uwb_rsv_queue_update(struct uwb_rc *rc)
+{
+	unsigned long delay_us = UWB_MAS_LENGTH_US * UWB_MAS_PER_ZONE;
+
+	queue_delayed_work(rc->rsv_workq, &rc->rsv_update_work, usecs_to_jiffies(delay_us));
+}
+
+/**
+ * uwb_rsv_sched_update - schedule an update of the DRP IEs
+ * @rc: the radio controller.
+ *
+ * To improve performance and ensure correctness with [ECMA-368] the
+ * number of SET-DRP-IE commands that are done are limited.
+ *
+ * DRP IEs update come from two sources: DRP events from the hardware
+ * which all occur at the beginning of the superframe ('syncronous'
+ * events) and reservation establishment/termination requests from
+ * PALs or timers ('asynchronous' events).
+ *
+ * A delayed work ensures that all the synchronous events result in
+ * one SET-DRP-IE command.
+ *
+ * Additional logic (the set_drp_ie_pending and rsv_updated_postponed
+ * flags) will prevent an asynchrous event starting a SET-DRP-IE
+ * command if one is currently awaiting a response.
+ *
+ * FIXME: this does leave a window where an asynchrous event can delay
+ * the SET-DRP-IE for a synchronous event by one superframe.
+ */
 void uwb_rsv_sched_update(struct uwb_rc *rc)
 {
-	queue_work(rc->rsv_workq, &rc->rsv_update_work);
+	spin_lock(&rc->rsvs_lock);
+	if (!delayed_work_pending(&rc->rsv_update_work)) {
+		if (rc->set_drp_ie_pending > 0) {
+			rc->set_drp_ie_pending++;
+			goto unlock;
+		}
+		uwb_rsv_queue_update(rc);
+	}
+unlock:
+	spin_unlock(&rc->rsvs_lock);
 }
 
 /*
···
  */
 static void uwb_rsv_update_work(struct work_struct *work)
 {
-	struct uwb_rc *rc = container_of(work, struct uwb_rc, rsv_update_work);
+	struct uwb_rc *rc = container_of(work, struct uwb_rc,
+					 rsv_update_work.work);
 	bool ie_updated;
 
 	mutex_lock(&rc->rsvs_mutex);
···
 		ie_updated = true;
 	}
 
-	if (ie_updated)
+	if (ie_updated && (rc->set_drp_ie_pending == 0))
 		uwb_rc_send_all_drp_ie(rc);
+
+	mutex_unlock(&rc->rsvs_mutex);
+}
+
+static void uwb_rsv_alien_bp_work(struct work_struct *work)
+{
+	struct uwb_rc *rc = container_of(work, struct uwb_rc,
+					 rsv_alien_bp_work.work);
+	struct uwb_rsv *rsv;
+
+	mutex_lock(&rc->rsvs_mutex);
+	
+	list_for_each_entry(rsv, &rc->reservations, rc_node) {
+		if (rsv->type != UWB_DRP_TYPE_ALIEN_BP) {
+			rsv->callback(rsv);
+		}
+	}
 
 	mutex_unlock(&rc->rsvs_mutex);
 }
···
 {
 	struct uwb_rsv *rsv = (struct uwb_rsv *)arg;
 
-	rsv->expired = true;
-	uwb_rsv_sched_update(rsv->rc);
+	queue_work(rsv->rc->rsv_workq, &rsv->handle_timeout_work);
 }
 
 /**
···
 	list_for_each_entry_safe(rsv, t, &rc->reservations, rc_node) {
 		uwb_rsv_remove(rsv);
 	}
+	/* Cancel any postponed update. */
+	rc->set_drp_ie_pending = 0;
 	mutex_unlock(&rc->rsvs_mutex);
 
-	cancel_work_sync(&rc->rsv_update_work);
+	cancel_delayed_work_sync(&rc->rsv_update_work);
 }
 
 void uwb_rsv_init(struct uwb_rc *rc)
 {
 	INIT_LIST_HEAD(&rc->reservations);
+	INIT_LIST_HEAD(&rc->cnflt_alien_list);
 	mutex_init(&rc->rsvs_mutex);
-	INIT_WORK(&rc->rsv_update_work, uwb_rsv_update_work);
+	spin_lock_init(&rc->rsvs_lock);
+	INIT_DELAYED_WORK(&rc->rsv_update_work, uwb_rsv_update_work);
+	INIT_DELAYED_WORK(&rc->rsv_alien_bp_work, uwb_rsv_alien_bp_work);
+	rc->bow.can_reserve_extra_mases = true;
+	rc->bow.total_expired = 0;
+	rc->bow.window = UWB_DRP_BACKOFF_WIN_MIN >> 1;
+	init_timer(&rc->bow.timer);
+	rc->bow.timer.function = uwb_rsv_backoff_win_timer;
+	rc->bow.timer.data     = (unsigned long)&rc->bow;
 
 	bitmap_complement(rc->uwb_dev.streams, rc->uwb_dev.streams, UWB_NUM_STREAMS);
 }

drivers/uwb/uwb-debug.c

···
 	struct dentry *reservations_f;
 	struct dentry *accept_f;
 	struct dentry *drp_avail_f;
+	spinlock_t list_lock;
 };
 
 static struct dentry *root_dir;
 
 static void uwb_dbg_rsv_cb(struct uwb_rsv *rsv)
 {
-	struct uwb_rc *rc = rsv->rc;
-	struct device *dev = &rc->uwb_dev.dev;
-	struct uwb_dev_addr devaddr;
-	char owner[UWB_ADDR_STRSIZE], target[UWB_ADDR_STRSIZE];
+	struct uwb_dbg *dbg = rsv->pal_priv;
 
-	uwb_dev_addr_print(owner, sizeof(owner), &rsv->owner->dev_addr);
-	if (rsv->target.type == UWB_RSV_TARGET_DEV)
-		devaddr = rsv->target.dev->dev_addr;
-	else
-		devaddr = rsv->target.devaddr;
-	uwb_dev_addr_print(target, sizeof(target), &devaddr);
-
-	dev_dbg(dev, "debug: rsv %s -> %s: %s\n",
-		owner, target, uwb_rsv_state_str(rsv->state));
+	uwb_rsv_dump("debug", rsv);
 
 	if (rsv->state == UWB_RSV_STATE_NONE) {
+		spin_lock(&dbg->list_lock);
 		list_del(&rsv->pal_node);
+		spin_unlock(&dbg->list_lock);
 		uwb_rsv_destroy(rsv);
 	}
 }
···
 		return -ENOMEM;
 	}
 
-	rsv->owner       = &rc->uwb_dev;
-	rsv->target.type = UWB_RSV_TARGET_DEV;
-	rsv->target.dev  = target;
-	rsv->type        = cmd->type;
-	rsv->max_mas     = cmd->max_mas;
-	rsv->min_mas     = cmd->min_mas;
-	rsv->sparsity    = cmd->sparsity;
+	rsv->target.type  = UWB_RSV_TARGET_DEV;
+	rsv->target.dev   = target;
+	rsv->type         = cmd->type;
+	rsv->max_mas      = cmd->max_mas;
+	rsv->min_mas      = cmd->min_mas;
+	rsv->max_interval = cmd->max_interval;
 
 	ret = uwb_rsv_establish(rsv);
 	if (ret)
 		uwb_rsv_destroy(rsv);
-	else
+	else {
+		spin_lock(&(rc->dbg)->list_lock);
 		list_add_tail(&rsv->pal_node, &rc->dbg->rsvs);
-
+		spin_unlock(&(rc->dbg)->list_lock);
+	}
 	return ret;
 }
 
···
 	struct uwb_rsv *rsv, *found = NULL;
 	int i = 0;
 
+	spin_lock(&(rc->dbg)->list_lock);
+
 	list_for_each_entry(rsv, &rc->dbg->rsvs, pal_node) {
 		if (i == cmd->index) {
 			found = rsv;
+			uwb_rsv_get(found);
 			break;
 		}
 		i++;
 	}
+
+	spin_unlock(&(rc->dbg)->list_lock);
+
 	if (!found)
 		return -EINVAL;
 
 	uwb_rsv_terminate(found);
+	uwb_rsv_put(found);
 
 	return 0;
 }
···
 	struct uwb_rc *rc = file->private_data;
 	struct uwb_dbg_cmd cmd;
 	int ret = 0;
-
+	
 	if (len != sizeof(struct uwb_dbg_cmd))
 		return -EINVAL;
 
···
 	struct uwb_dbg *dbg = container_of(pal, struct uwb_dbg, pal);
 
 	if (dbg->accept) {
+		spin_lock(&dbg->list_lock);
 		list_add_tail(&rsv->pal_node, &dbg->rsvs);
+		spin_unlock(&dbg->list_lock);
 		uwb_rsv_accept(rsv, uwb_dbg_rsv_cb, dbg);
 	}
 }
···
 		return;
 
 	INIT_LIST_HEAD(&rc->dbg->rsvs);
+	spin_lock_init(&(rc->dbg)->list_lock);
 
 	uwb_pal_init(&rc->dbg->pal);
 	rc->dbg->pal.rc = rc;

drivers/uwb/uwb-internal.h

···
 
 struct uwb_rc_neh;
 
+extern int uwb_rc_cmd_async(struct uwb_rc *rc, const char *cmd_name,
+			    struct uwb_rccb *cmd, size_t cmd_size,
+			    u8 expected_type, u16 expected_event,
+			    uwb_rc_cmd_cb_f cb, void *arg);
+
+
 void uwb_rc_neh_create(struct uwb_rc *rc);
 void uwb_rc_neh_destroy(struct uwb_rc *rc);
 
···
 extern int uwb_est_create(void);
 extern void uwb_est_destroy(void);
 
+/*
+ * UWB conflicting alien reservations
+ */
+struct uwb_cnflt_alien {
+	struct uwb_rc *rc;
+	struct list_head rc_node;
+	struct uwb_mas_bm mas;
+	struct timer_list timer;
+	struct work_struct cnflt_update_work;
+};
 
+enum uwb_uwb_rsv_alloc_result {
+	UWB_RSV_ALLOC_FOUND = 0,
+	UWB_RSV_ALLOC_NOT_FOUND,
+};
+
+enum uwb_rsv_mas_status {
+	UWB_RSV_MAS_NOT_AVAIL = 1,
+	UWB_RSV_MAS_SAFE,
+	UWB_RSV_MAS_UNSAFE,
+};
+
+struct uwb_rsv_col_set_info {
+	unsigned char start_col;
+	unsigned char interval;
+	unsigned char safe_mas_per_col;
+	unsigned char unsafe_mas_per_col;
+};
+
+struct uwb_rsv_col_info {
+	unsigned char max_avail_safe;
+	unsigned char max_avail_unsafe;
+	unsigned char highest_mas[UWB_MAS_PER_ZONE];
+	struct uwb_rsv_col_set_info csi;
+};
+
+struct uwb_rsv_row_info {
+	unsigned char avail[UWB_MAS_PER_ZONE];
+	unsigned char free_rows;
+	unsigned char used_rows;
+};
+
+/*
+ * UWB find allocation
+ */
+struct uwb_rsv_alloc_info {
+	unsigned char bm[UWB_MAS_PER_ZONE * UWB_NUM_ZONES];
+	struct uwb_rsv_col_info ci[UWB_NUM_ZONES];
+	struct uwb_rsv_row_info ri;
+	struct uwb_mas_bm *not_available;
+	struct uwb_mas_bm *result;
+	int min_mas;
+	int max_mas;
+	int max_interval;
+	int total_allocated_mases;
+	int safe_allocated_mases;
+	int unsafe_allocated_mases;
+	int interval;
+};
+
+int uwb_rsv_find_best_allocation(struct uwb_rsv *rsv, struct uwb_mas_bm *available, 
+				 struct uwb_mas_bm *result);
+void uwb_rsv_handle_drp_avail_change(struct uwb_rc *rc);
 /*
  * UWB Events & management daemon
  */
···
 int uwb_rsv_setup(struct uwb_rc *rc);
 void uwb_rsv_cleanup(struct uwb_rc *rc);
 void uwb_rsv_remove_all(struct uwb_rc *rc);
+void uwb_rsv_get(struct uwb_rsv *rsv);
+void uwb_rsv_put(struct uwb_rsv *rsv);
+bool uwb_rsv_has_two_drp_ies(struct uwb_rsv *rsv);
+void uwb_rsv_dump(char *text, struct uwb_rsv *rsv);
+int uwb_rsv_try_move(struct uwb_rsv *rsv, struct uwb_mas_bm *available);
+void uwb_rsv_backoff_win_timer(unsigned long arg);
+void uwb_rsv_backoff_win_increment(struct uwb_rc *rc);
+int uwb_rsv_status(struct uwb_rsv *rsv);
+int uwb_rsv_companion_status(struct uwb_rsv *rsv);
 
 void uwb_rsv_set_state(struct uwb_rsv *rsv, enum uwb_rsv_state new_state);
 void uwb_rsv_remove(struct uwb_rsv *rsv);
 struct uwb_rsv *uwb_rsv_find(struct uwb_rc *rc, struct uwb_dev *src,
 			     struct uwb_ie_drp *drp_ie);
 void uwb_rsv_sched_update(struct uwb_rc *rc);
+void uwb_rsv_queue_update(struct uwb_rc *rc);
 
-void uwb_drp_handle_timeout(struct uwb_rsv *rsv);
 int uwb_drp_ie_update(struct uwb_rsv *rsv);
 void uwb_drp_ie_to_bm(struct uwb_mas_bm *bm, const struct uwb_ie_drp *drp_ie);
 
 void uwb_drp_avail_init(struct uwb_rc *rc);
+void uwb_drp_available(struct uwb_rc *rc, struct uwb_mas_bm *avail);
 int  uwb_drp_avail_reserve_pending(struct uwb_rc *rc, struct uwb_mas_bm *mas);
 void uwb_drp_avail_reserve(struct uwb_rc *rc, struct uwb_mas_bm *mas);
 void uwb_drp_avail_release(struct uwb_rc *rc, struct uwb_mas_bm *mas);

include/linux/uwb.h

···
 	struct uwb_dev_addr dev_addr;
 	int beacon_slot;
 	DECLARE_BITMAP(streams, UWB_NUM_STREAMS);
+	DECLARE_BITMAP(last_availability_bm, UWB_NUM_MAS);
 };
 #define to_uwb_dev(d) container_of(d, struct uwb_dev, dev)
 
···
  */
 struct uwb_mas_bm {
 	DECLARE_BITMAP(bm, UWB_NUM_MAS);
+	DECLARE_BITMAP(unsafe_bm, UWB_NUM_MAS);
+	int safe;
+	int unsafe;
 };
 
 /**
···
  * FIXME: further target states TBD.
  */
 enum uwb_rsv_state {
-	UWB_RSV_STATE_NONE,
+	UWB_RSV_STATE_NONE = 0,
 	UWB_RSV_STATE_O_INITIATED,
 	UWB_RSV_STATE_O_PENDING,
 	UWB_RSV_STATE_O_MODIFIED,
 	UWB_RSV_STATE_O_ESTABLISHED,
+	UWB_RSV_STATE_O_TO_BE_MOVED,
+	UWB_RSV_STATE_O_MOVE_EXPANDING,
+	UWB_RSV_STATE_O_MOVE_COMBINING,
+	UWB_RSV_STATE_O_MOVE_REDUCING,
 	UWB_RSV_STATE_T_ACCEPTED,
 	UWB_RSV_STATE_T_DENIED,
+	UWB_RSV_STATE_T_CONFLICT,
 	UWB_RSV_STATE_T_PENDING,
+	UWB_RSV_STATE_T_EXPANDING_ACCEPTED,
+	UWB_RSV_STATE_T_EXPANDING_CONFLICT,
+	UWB_RSV_STATE_T_EXPANDING_PENDING,
+	UWB_RSV_STATE_T_EXPANDING_DENIED,
+	UWB_RSV_STATE_T_RESIZED,
 
 	UWB_RSV_STATE_LAST,
 };
···
 		struct uwb_dev *dev;
 		struct uwb_dev_addr devaddr;
 	};
+};
+
+struct uwb_rsv_move {
+	struct uwb_mas_bm final_mas;
+	struct uwb_ie_drp *companion_drp_ie;
+	struct uwb_mas_bm companion_mas;
 };
 
 /*
···
  *
  * @status:         negotiation status
  * @stream:         stream index allocated for this reservation
+ * @tiebreaker:     conflict tiebreaker for this reservation
  * @mas:            reserved MAS
  * @drp_ie:         the DRP IE
  * @ie_valid:       true iff the DRP IE matches the reservation parameters
···
 	enum uwb_drp_type type;
 	int max_mas;
 	int min_mas;
-	int sparsity;
+	int max_interval;
 	bool is_multicast;
 
 	uwb_rsv_cb_f callback;
 	void *pal_priv;
 
 	enum uwb_rsv_state state;
+	bool needs_release_companion_mas;
 	u8 stream;
+	u8 tiebreaker;
 	struct uwb_mas_bm mas;
 	struct uwb_ie_drp *drp_ie;
+	struct uwb_rsv_move mv;
 	bool ie_valid;
 	struct timer_list timer;
-	bool expired;
+	struct work_struct handle_timeout_work;
 };
 
 static const
···
 	bool ie_valid;
 };
 
+struct uwb_drp_backoff_win {
+	u8 window;
+	u8 n;
+	int total_expired;
+	struct timer_list timer;
+	bool can_reserve_extra_mases;
+};
 
 const char *uwb_rsv_state_str(enum uwb_rsv_state state);
 const char *uwb_rsv_type_str(enum uwb_drp_type type);
···
 void uwb_rsv_terminate(struct uwb_rsv *rsv);
 
 void uwb_rsv_accept(struct uwb_rsv *rsv, uwb_rsv_cb_f cb, void *pal_priv);
+
+void uwb_rsv_get_usable_mas(struct uwb_rsv *orig_rsv, struct uwb_mas_bm *mas);
 
 /**
  * Radio Control Interface instance
···
 
 	struct uwbd uwbd;
 
+	struct uwb_drp_backoff_win bow;
 	struct uwb_drp_avail drp_avail;
 	struct list_head reservations;
+	struct list_head cnflt_alien_list;
+	struct uwb_mas_bm cnflt_alien_bitmap;
 	struct mutex rsvs_mutex;
+	spinlock_t rsvs_lock;
 	struct workqueue_struct *rsv_workq;
-	struct work_struct rsv_update_work;
 
+	struct delayed_work rsv_update_work;
+	struct delayed_work rsv_alien_bp_work;
+	int set_drp_ie_pending;
 	struct mutex ies_mutex;
 	struct uwb_rc_cmd_set_ie *ies;
 	size_t ies_capacity;

include/linux/uwb/debug-cmd.h

···
 	__u8  type;
 	__u16 max_mas;
 	__u16 min_mas;
-	__u8  sparsity;
+	__u8  max_interval;
 };
 
 struct uwb_dbg_cmd_rsv_terminate {

include/linux/uwb/spec.h

···
 #define UWB_MAS_PER_ZONE (UWB_NUM_MAS / UWB_NUM_ZONES)
 
 /*
+ * Number of MAS required before a row can be considered available.
+ */
+#define UWB_USABLE_MAS_PER_ROW (UWB_NUM_ZONES - 1)
+
+/*
  * Number of streams per DRP reservation between a pair of devices.
  *
  * [ECMA-368] section 16.8.6.
···
  * [ECMA-368] section 17.16
  */
 enum { UWB_MAX_LOST_BEACONS = 3 };
+
+/*
+ * mDRPBackOffWinMin
+ *
+ * The minimum number of superframes to wait before trying to reserve
+ * extra MAS.
+ *
+ * [ECMA-368] section 17.16
+ */
+enum { UWB_DRP_BACKOFF_WIN_MIN = 2 };
+
+/*
+ * mDRPBackOffWinMax
+ *
+ * The maximum number of superframes to wait before trying to reserve
+ * extra MAS.
+ *
+ * [ECMA-368] section 17.16
+ */
+enum { UWB_DRP_BACKOFF_WIN_MAX = 16 };
 
 /*
  * Length of a superframe in microseconds.