Merge tag 'driver-core-3.5-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core and printk fixes from Greg Kroah-Hartman:
"Here are some fixes for 3.5-rc4 that resolve the kmsg problems that
people have reported showing up after the printk and kmsg changes went
into 3.5-rc1. There are also a smattering of other tiny fixes for the
extcon and hyper-v drivers that people have reported.

Signed-off-by: Greg Kroah-Hartman <[e-mail]>"

* tag 'driver-core-3.5-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
extcon: max8997: Add missing kfree for info->edev in max8997_muic_remove()
extcon: Set platform drvdata in gpio_extcon_probe() and fix irq leak
extcon: Fix wrong index in max8997_extcon_cable[]
kmsg - kmsg_dump() fix CONFIG_PRINTK=n compilation
printk: return -EINVAL if the message len is bigger than the buf size
printk: use mutex lock to stop syslog_seq from going wild
kmsg - kmsg_dump() use iterator to receive log buffer content
vme: change maintainer e-mail address
Extcon: Don't try to create duplicate link names
driver core: fixup reversed deferred probe order
printk: Fix alignment of buf causing crash on ARM EABI
Tools: hv: verify origin of netlink connector message

MAINTAINERS

···
 
 VME SUBSYSTEM
 M:	Martyn Welch <[e-mail]>
-M:	Manohar Vanga <[e-mail]>
+M:	Manohar Vanga <[e-mail]>
 M:	Greg Kroah-Hartman <[e-mail]>
 L:	[e-mail]
 S:	Maintained

arch/powerpc/platforms/pseries/nvram.c

···
 };
 
 static void oops_to_nvram(struct kmsg_dumper *dumper,
-		enum kmsg_dump_reason reason,
-		const char *old_msgs, unsigned long old_len,
-		const char *new_msgs, unsigned long new_len);
+			  enum kmsg_dump_reason reason);
 
 static struct kmsg_dumper nvram_kmsg_dumper = {
 	.dump = oops_to_nvram
···
 }
 
 /*
- * Try to capture the last capture_len bytes of the printk buffer.  Return
- * the amount actually captured.
- */
-static size_t capture_last_msgs(const char *old_msgs, size_t old_len,
-				const char *new_msgs, size_t new_len,
-				char *captured, size_t capture_len)
-{
-	if (new_len >= capture_len) {
-		memcpy(captured, new_msgs + (new_len - capture_len),
-								capture_len);
-		return capture_len;
-	} else {
-		/* Grab the end of old_msgs. */
-		size_t old_tail_len = min(old_len, capture_len - new_len);
-		memcpy(captured, old_msgs + (old_len - old_tail_len),
-								old_tail_len);
-		memcpy(captured + old_tail_len, new_msgs, new_len);
-		return old_tail_len + new_len;
-	}
-}
-
-/*
  * Are we using the ibm,rtas-log for oops/panic reports?  And if so,
  * would logging this oops/panic overwrite an RTAS event that rtas_errd
  * hasn't had a chance to read and process?  Return 1 if so, else 0.
···
 		&& last_unread_rtas_event
 		&& get_seconds() - last_unread_rtas_event <=
 						NVRAM_RTAS_READ_TIMEOUT);
-}
-
-/* Squeeze out each line's <n> severity prefix. */
-static size_t elide_severities(char *buf, size_t len)
-{
-	char *in, *out, *buf_end = buf + len;
-	/* Assume a <n> at the very beginning marks the start of a line. */
-	int newline = 1;
-
-	in = out = buf;
-	while (in < buf_end) {
-		if (newline && in+3 <= buf_end &&
-				*in == '<' && isdigit(in[1]) && in[2] == '>') {
-			in += 3;
-			newline = 0;
-		} else {
-			newline = (*in == '\n');
-			*out++ = *in++;
-		}
-	}
-	return out - buf;
 }
 
 /* Derived from logfs_compress() */
···
  * partition.  If that's too much, go back and capture uncompressed text.
  */
 static void oops_to_nvram(struct kmsg_dumper *dumper,
-		enum kmsg_dump_reason reason,
-		const char *old_msgs, unsigned long old_len,
-		const char *new_msgs, unsigned long new_len)
+			  enum kmsg_dump_reason reason)
 {
 	static unsigned int oops_count = 0;
 	static bool panicking = false;
···
 		return;
 
 	if (big_oops_buf) {
-		text_len = capture_last_msgs(old_msgs, old_len,
-			new_msgs, new_len, big_oops_buf, big_oops_buf_sz);
-		text_len = elide_severities(big_oops_buf, text_len);
+		kmsg_dump_get_buffer(dumper, false,
+				     big_oops_buf, big_oops_buf_sz, &text_len);
 		rc = zip_oops(text_len);
 	}
 	if (rc != 0) {
-		text_len = capture_last_msgs(old_msgs, old_len,
-				new_msgs, new_len, oops_data, oops_data_sz);
+		kmsg_dump_rewind(dumper);
+		kmsg_dump_get_buffer(dumper, true,
+				     oops_data, oops_data_sz, &text_len);
 		err_type = ERR_TYPE_KERNEL_PANIC;
 		*oops_len = (u16) text_len;
 	}

arch/x86/platform/mrst/early_printk_mrst.c

···
 static int dumper_registered;
 
 static void dw_kmsg_dump(struct kmsg_dumper *dumper,
-			enum kmsg_dump_reason reason,
-			const char *s1, unsigned long l1,
-			const char *s2, unsigned long l2)
+			 enum kmsg_dump_reason reason)
 {
-	int i;
+	static char line[1024];
+	size_t len;
 
 	/* When run to this, we'd better re-init the HW */
 	mrst_early_console_init();
 
-	for (i = 0; i < l1; i++)
-		early_mrst_console.write(&early_mrst_console, s1 + i, 1);
-	for (i = 0; i < l2; i++)
-		early_mrst_console.write(&early_mrst_console, s2 + i, 1);
+	while (kmsg_dump_get_line(dumper, true, line, sizeof(line), &len))
+		early_mrst_console.write(&early_mrst_console, line, len);
 }
 
 /* Set the ratio rate to 115200, 8n1, IRQ disabled */

drivers/base/dd.c

···
 	mutex_lock(&deferred_probe_mutex);
 	if (list_empty(&dev->p->deferred_probe)) {
 		dev_dbg(dev, "Added to deferred list\n");
-		list_add(&dev->p->deferred_probe, &deferred_probe_pending_list);
+		list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
 	}
 	mutex_unlock(&deferred_probe_mutex);
 }

drivers/extcon/extcon-max8997.c

···
 	[5] = "Charge-downstream",
 	[6] = "MHL",
 	[7] = "Dock-desk",
-	[7] = "Dock-card",
-	[8] = "JIG",
+	[8] = "Dock-card",
+	[9] = "JIG",
 
 	NULL,
 };
···
 
 	extcon_dev_unregister(info->edev);
 
+	kfree(info->edev);
 	kfree(info);
 
 	return 0;

drivers/extcon/extcon_class.c

···
 #if defined(CONFIG_ANDROID)
 	if (switch_class)
 		ret = class_compat_create_link(switch_class, edev->dev,
-					       dev);
+					       NULL);
 #endif /* CONFIG_ANDROID */
 
 	spin_lock_init(&edev->lock);

drivers/extcon/extcon_gpio.c

···
 	if (ret < 0)
 		goto err_request_irq;
 
+	platform_set_drvdata(pdev, extcon_data);
 	/* Perform initial detection */
 	gpio_extcon_work(&extcon_data->work.work);
 
···
 	struct gpio_extcon_data *extcon_data = platform_get_drvdata(pdev);
 
 	cancel_delayed_work_sync(&extcon_data->work);
+	free_irq(extcon_data->irq, extcon_data);
 	gpio_free(extcon_data->gpio);
 	extcon_dev_unregister(&extcon_data->edev);
 	devm_kfree(&pdev->dev, extcon_data);

drivers/mtd/mtdoops.c

···
 }
 
 static void mtdoops_do_dump(struct kmsg_dumper *dumper,
-		enum kmsg_dump_reason reason, const char *s1, unsigned long l1,
-		const char *s2, unsigned long l2)
+			    enum kmsg_dump_reason reason)
 {
 	struct mtdoops_context *cxt = container_of(dumper,
 			struct mtdoops_context, dump);
-	unsigned long s1_start, s2_start;
-	unsigned long l1_cpy, l2_cpy;
-	char *dst;
-
-	if (reason != KMSG_DUMP_OOPS &&
-	    reason != KMSG_DUMP_PANIC)
-		return;
 
 	/* Only dump oopses if dump_oops is set */
 	if (reason == KMSG_DUMP_OOPS && !dump_oops)
 		return;
 
-	dst = cxt->oops_buf + MTDOOPS_HEADER_SIZE; /* Skip the header */
-	l2_cpy = min(l2, record_size - MTDOOPS_HEADER_SIZE);
-	l1_cpy = min(l1, record_size - MTDOOPS_HEADER_SIZE - l2_cpy);
-
-	s2_start = l2 - l2_cpy;
-	s1_start = l1 - l1_cpy;
-
-	memcpy(dst, s1 + s1_start, l1_cpy);
-	memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
+	kmsg_dump_get_buffer(dumper, true, cxt->oops_buf + MTDOOPS_HEADER_SIZE,
+			     record_size - MTDOOPS_HEADER_SIZE, NULL);
 
 	/* Panics must be written immediately */
 	if (reason != KMSG_DUMP_OOPS)
···
 		return;
 	}
 
+	cxt->dump.max_reason = KMSG_DUMP_OOPS;
 	cxt->dump.dump = mtdoops_do_dump;
 	err = kmsg_dump_register(&cxt->dump);
 	if (err) {

fs/pstore/platform.c

···
  * as we can from the end of the buffer.
  */
 static void pstore_dump(struct kmsg_dumper *dumper,
-	    enum kmsg_dump_reason reason,
-	    const char *s1, unsigned long l1,
-	    const char *s2, unsigned long l2)
+			enum kmsg_dump_reason reason)
 {
-	unsigned long	s1_start, s2_start;
-	unsigned long	l1_cpy, l2_cpy;
-	unsigned long	size, total = 0;
-	char		*dst;
+	unsigned long	total = 0;
 	const char	*why;
 	u64		id;
-	int		hsize, ret;
 	unsigned int	part = 1;
 	unsigned long	flags = 0;
 	int		is_locked = 0;
+	int		ret;
 
 	why = get_reason_str(reason);
 
···
 		spin_lock_irqsave(&psinfo->buf_lock, flags);
 	oopscount++;
 	while (total < kmsg_bytes) {
+		char *dst;
+		unsigned long size;
+		int hsize;
+		size_t len;
+
 		dst = psinfo->buf;
 		hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
 		size = psinfo->bufsize - hsize;
 		dst += hsize;
 
-		l2_cpy = min(l2, size);
-		l1_cpy = min(l1, size - l2_cpy);
-
-		if (l1_cpy + l2_cpy == 0)
+		if (!kmsg_dump_get_buffer(dumper, true, dst, size, &len))
 			break;
 
-		s2_start = l2 - l2_cpy;
-		s1_start = l1 - l1_cpy;
-
-		memcpy(dst, s1 + s1_start, l1_cpy);
-		memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
-
 		ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
-				   hsize + l1_cpy + l2_cpy, psinfo);
+				    hsize + len, psinfo);
 		if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 			pstore_new_entry = 1;
-		l1 -= l1_cpy;
-		l2 -= l2_cpy;
-		total += l1_cpy + l2_cpy;
+
+		total += hsize + len;
 		part++;
 	}
 	if (in_nmi()) {

include/linux/kmsg_dump.h

···
  * is passed to the kernel.
  */
 enum kmsg_dump_reason {
+	KMSG_DUMP_UNDEF,
 	KMSG_DUMP_PANIC,
 	KMSG_DUMP_OOPS,
 	KMSG_DUMP_EMERG,
···
 
 /**
  * struct kmsg_dumper - kernel crash message dumper structure
- * @dump:	The callback which gets called on crashes. The buffer is passed
- * 		as two sections, where s1 (length l1) contains the older
- * 		messages and s2 (length l2) contains the newer.
  * @list:	Entry in the dumper list (private)
+ * @dump:	Call into dumping code which will retrieve the data with
+ * 		through the record iterator
+ * @max_reason:	filter for highest reason number that should be dumped
  * @registered:	Flag that specifies if this is already registered
  */
 struct kmsg_dumper {
-	void (*dump)(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason,
-			const char *s1, unsigned long l1,
-			const char *s2, unsigned long l2);
 	struct list_head list;
-	int registered;
+	void (*dump)(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason);
+	enum kmsg_dump_reason max_reason;
+	bool active;
+	bool registered;
+
+	/* private state of the kmsg iterator */
+	u32 cur_idx;
+	u32 next_idx;
+	u64 cur_seq;
+	u64 next_seq;
 };
 
 #ifdef CONFIG_PRINTK
 void kmsg_dump(enum kmsg_dump_reason reason);
+
+bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
+			char *line, size_t size, size_t *len);
+
+bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
+			  char *buf, size_t size, size_t *len);
+
+void kmsg_dump_rewind(struct kmsg_dumper *dumper);
 
 int kmsg_dump_register(struct kmsg_dumper *dumper);
 
 int kmsg_dump_unregister(struct kmsg_dumper *dumper);
 #else
 static inline void kmsg_dump(enum kmsg_dump_reason reason)
+{
+}
+
+static inline bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
+				const char *line, size_t size, size_t *len)
+{
+	return false;
+}
+
+static inline bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
+					char *buf, size_t size, size_t *len)
+{
+	return false;
+}
+
+static inline void kmsg_dump_rewind(struct kmsg_dumper *dumper)
 {
 }
 

kernel/printk.c

···
 #define LOG_LINE_MAX 1024
 
 /* record buffer */
-#if !defined(CONFIG_64BIT) || defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
 #define LOG_ALIGN 4
 #else
-#define LOG_ALIGN 8
+#define LOG_ALIGN __alignof__(struct log)
 #endif
 #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
 static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
···
 	if (!user)
 		return -EBADF;
 
-	mutex_lock(&user->lock);
+	ret = mutex_lock_interruptible(&user->lock);
+	if (ret)
+		return ret;
 	raw_spin_lock(&logbuf_lock);
 	while (user->seq == log_next_seq) {
 		if (file->f_flags & O_NONBLOCK) {
···
 	syslog_seq++;
 	raw_spin_unlock_irq(&logbuf_lock);
 
-	if (len > 0 && copy_to_user(buf, text, len))
+	if (len > size)
+		len = -EINVAL;
+	else if (len > 0 && copy_to_user(buf, text, len))
 		len = -EFAULT;
 
 	kfree(text);
···
 		/*
 		 * Find first record that fits, including all following records,
 		 * into the user-provided buffer for this dump.
-		*/
+		 */
 		seq = clear_seq;
 		idx = clear_idx;
 		while (seq < log_next_seq) {
···
 			idx = log_next(idx);
 			seq++;
 		}
+
+		/* move first record forward until length fits into the buffer */
 		seq = clear_seq;
 		idx = clear_idx;
 		while (len > size && seq < log_next_seq) {
···
 			seq++;
 		}
 
-		/* last message in this dump */
+		/* last message fitting into this dump */
 		next_seq = log_next_seq;
 
 		len = 0;
···
 {
 	bool clear = false;
 	static int saved_console_loglevel = -1;
+	static DEFINE_MUTEX(syslog_mutex);
 	int error;
 
 	error = check_syslog_permissions(type, from_file);
···
 			error = -EFAULT;
 			goto out;
 		}
-		error = wait_event_interruptible(log_wait,
-						 syslog_seq != log_next_seq);
+		error = mutex_lock_interruptible(&syslog_mutex);
 		if (error)
 			goto out;
+		error = wait_event_interruptible(log_wait,
+						 syslog_seq != log_next_seq);
+		if (error) {
+			mutex_unlock(&syslog_mutex);
+			goto out;
+		}
 		error = syslog_print(buf, len);
+		mutex_unlock(&syslog_mutex);
 		break;
 	/* Read/clear last kernel messages */
 	case SYSLOG_ACTION_READ_CLEAR:
···
  * kmsg_dump - dump kernel log to kernel message dumpers.
  * @reason: the reason (oops, panic etc) for dumping
  *
- * Iterate through each of the dump devices and call the oops/panic
- * callbacks with the log buffer.
+ * Call each of the registered dumper's dump() callback, which can
+ * retrieve the kmsg records with kmsg_dump_get_line() or
+ * kmsg_dump_get_buffer().
  */
 void kmsg_dump(enum kmsg_dump_reason reason)
 {
-	u64 idx;
 	struct kmsg_dumper *dumper;
-	const char *s1, *s2;
-	unsigned long l1, l2;
 	unsigned long flags;
 
 	if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump)
 		return;
 
-	/* Theoretically, the log could move on after we do this, but
-	   there's not a lot we can do about that. The new messages
-	   will overwrite the start of what we dump. */
-
-	raw_spin_lock_irqsave(&logbuf_lock, flags);
-	if (syslog_seq < log_first_seq)
-		idx = syslog_idx;
-	else
-		idx = log_first_idx;
-
-	if (idx > log_next_idx) {
-		s1 = log_buf;
-		l1 = log_next_idx;
-
-		s2 = log_buf + idx;
-		l2 = log_buf_len - idx;
-	} else {
-		s1 = "";
-		l1 = 0;
-
-		s2 = log_buf + idx;
-		l2 = log_next_idx - idx;
-	}
-	raw_spin_unlock_irqrestore(&logbuf_lock, flags);
-
 	rcu_read_lock();
-	list_for_each_entry_rcu(dumper, &dump_list, list)
-		dumper->dump(dumper, reason, s1, l1, s2, l2);
+	list_for_each_entry_rcu(dumper, &dump_list, list) {
+		if (dumper->max_reason && reason > dumper->max_reason)
+			continue;
+
+		/* initialize iterator with data about the stored records */
+		dumper->active = true;
+
+		raw_spin_lock_irqsave(&logbuf_lock, flags);
+		dumper->cur_seq = clear_seq;
+		dumper->cur_idx = clear_idx;
+		dumper->next_seq = log_next_seq;
+		dumper->next_idx = log_next_idx;
+		raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+
+		/* invoke dumper which will iterate over records */
+		dumper->dump(dumper, reason);
+
+		/* reset iterator */
+		dumper->active = false;
+	}
 	rcu_read_unlock();
 }
+
+/**
+ * kmsg_dump_get_line - retrieve one kmsg log line
+ * @dumper: registered kmsg dumper
+ * @syslog: include the "<4>" prefixes
+ * @line: buffer to copy the line to
+ * @size: maximum size of the buffer
+ * @len: length of line placed into buffer
+ *
+ * Start at the beginning of the kmsg buffer, with the oldest kmsg
+ * record, and copy one record into the provided buffer.
+ *
+ * Consecutive calls will return the next available record moving
+ * towards the end of the buffer with the youngest messages.
+ *
+ * A return value of FALSE indicates that there are no more records to
+ * read.
+ */
+bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
+			char *line, size_t size, size_t *len)
+{
+	unsigned long flags;
+	struct log *msg;
+	size_t l = 0;
+	bool ret = false;
+
+	if (!dumper->active)
+		goto out;
+
+	raw_spin_lock_irqsave(&logbuf_lock, flags);
+	if (dumper->cur_seq < log_first_seq) {
+		/* messages are gone, move to first available one */
+		dumper->cur_seq = log_first_seq;
+		dumper->cur_idx = log_first_idx;
+	}
+
+	/* last entry */
+	if (dumper->cur_seq >= log_next_seq) {
+		raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+		goto out;
+	}
+
+	msg = log_from_idx(dumper->cur_idx);
+	l = msg_print_text(msg, syslog,
+			      line, size);
+
+	dumper->cur_idx = log_next(dumper->cur_idx);
+	dumper->cur_seq++;
+	ret = true;
+	raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+out:
+	if (len)
+		*len = l;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_get_line);
+
+/**
+ * kmsg_dump_get_buffer - copy kmsg log lines
+ * @dumper: registered kmsg dumper
+ * @syslog: include the "<4>" prefixes
+ * @line: buffer to copy the line to
+ * @size: maximum size of the buffer
+ * @len: length of line placed into buffer
+ *
+ * Start at the end of the kmsg buffer and fill the provided buffer
+ * with as many of the the *youngest* kmsg records that fit into it.
+ * If the buffer is large enough, all available kmsg records will be
+ * copied with a single call.
+ *
+ * Consecutive calls will fill the buffer with the next block of
+ * available older records, not including the earlier retrieved ones.
+ *
+ * A return value of FALSE indicates that there are no more records to
+ * read.
+ */
+bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
+			  char *buf, size_t size, size_t *len)
+{
+	unsigned long flags;
+	u64 seq;
+	u32 idx;
+	u64 next_seq;
+	u32 next_idx;
+	size_t l = 0;
+	bool ret = false;
+
+	if (!dumper->active)
+		goto out;
+
+	raw_spin_lock_irqsave(&logbuf_lock, flags);
+	if (dumper->cur_seq < log_first_seq) {
+		/* messages are gone, move to first available one */
+		dumper->cur_seq = log_first_seq;
+		dumper->cur_idx = log_first_idx;
+	}
+
+	/* last entry */
+	if (dumper->cur_seq >= dumper->next_seq) {
+		raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+		goto out;
+	}
+
+	/* calculate length of entire buffer */
+	seq = dumper->cur_seq;
+	idx = dumper->cur_idx;
+	while (seq < dumper->next_seq) {
+		struct log *msg = log_from_idx(idx);
+
+		l += msg_print_text(msg, true, NULL, 0);
+		idx = log_next(idx);
+		seq++;
+	}
+
+	/* move first record forward until length fits into the buffer */
+	seq = dumper->cur_seq;
+	idx = dumper->cur_idx;
+	while (l > size && seq < dumper->next_seq) {
+		struct log *msg = log_from_idx(idx);
+
+		l -= msg_print_text(msg, true, NULL, 0);
+		idx = log_next(idx);
+		seq++;
+	}
+
+	/* last message in next interation */
+	next_seq = seq;
+	next_idx = idx;
+
+	l = 0;
+	while (seq < dumper->next_seq) {
+		struct log *msg = log_from_idx(idx);
+
+		l += msg_print_text(msg, syslog,
+				    buf + l, size - l);
+
+		idx = log_next(idx);
+		seq++;
+	}
+
+	dumper->next_seq = next_seq;
+	dumper->next_idx = next_idx;
+	ret = true;
+	raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+out:
+	if (len)
+		*len = l;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
+
+/**
+ * kmsg_dump_rewind - reset the interator
+ * @dumper: registered kmsg dumper
+ *
+ * Reset the dumper's iterator so that kmsg_dump_get_line() and
+ * kmsg_dump_get_buffer() can be called again and used multiple
+ * times within the same dumper.dump() callback.
+ */
+void kmsg_dump_rewind(struct kmsg_dumper *dumper)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&logbuf_lock, flags);
+	dumper->cur_seq = clear_seq;
+	dumper->cur_idx = clear_idx;
+	dumper->next_seq = log_next_seq;
+	dumper->next_idx = log_next_idx;
+	raw_spin_unlock_irqrestore(&logbuf_lock, flags);
+}
+EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
 #endif

tools/hv/hv_kvp_daemon.c

···
 	pfd.fd = fd;
 
 	while (1) {
+		struct sockaddr *addr_p = (struct sockaddr *) &addr;
+		socklen_t addr_l = sizeof(addr);
 		pfd.events = POLLIN;
 		pfd.revents = 0;
 		poll(&pfd, 1, -1);
 
-		len = recv(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0);
+		len = recvfrom(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0,
+				addr_p, &addr_l);
 
-		if (len < 0) {
-			syslog(LOG_ERR, "recv failed; error:%d", len);
+		if (len < 0 || addr.nl_pid) {
+			syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s",
+					addr.nl_pid, errno, strerror(errno));
 			close(fd);
 			return -1;
 		}