ieee1394: nodemgr: parallelize between several hosts

Remove the global nodemgr_serialize mutex which enclosed most of the
host thread event loop. This allows for parallelism between several
host adapter cards.

Properly serialize the driver hooks .update(), .suspend(), .resume(),
and .remove() by means of device->sem. These hooks can be called from
outside the host threads' contexts.

Get() and put() the device.driver when calling its hooks.

Signed-off-by: Stefan Richter <[e-mail]>

drivers/ieee1394/nodemgr.c

···
 #include <linux/mutex.h>
 #include <linux/freezer.h>
 #include <asm/atomic.h>
+#include <asm/semaphore.h>
 
 #include "csr.h"
 #include "highlevel.h"
···
  * driver/device mappings. The old nodemgr used to handle all this itself,
  * but now we are much simpler because of the LDM.
  */
-
-static DEFINE_MUTEX(nodemgr_serialize);
 
 struct host_info {
 	struct hpsb_host *host;
···
 {
 	struct device *dev;
 	struct unit_directory *ud;
+	struct device_driver *drv;
+	int error;
 
 	HPSB_DEBUG("Node suspended: ID:BUS[" NODE_BUS_FMT "]  GUID[%016Lx]",
 		   NODE_BUS_ARGS(ne->host, ne->nodeid), (unsigned long long)ne->guid);
···
 		if (ud->ne != ne)
 			continue;
 
-		if (ud->device.driver &&
-		    (!ud->device.driver->suspend ||
-		      ud->device.driver->suspend(&ud->device, PMSG_SUSPEND)))
+		drv = get_driver(ud->device.driver);
+		if (!drv)
+			continue;
+
+		error = 1; /* release if suspend is not implemented */
+		if (drv->suspend) {
+			down(&ud->device.sem);
+			error = drv->suspend(&ud->device, PMSG_SUSPEND);
+			up(&ud->device.sem);
+		}
+		if (error)
 			device_release_driver(&ud->device);
+		put_driver(drv);
 	}
 	up(&nodemgr_ud_class.sem);
 }
···
 {
 	struct device *dev;
 	struct unit_directory *ud;
+	struct device_driver *drv;
 
 	ne->in_limbo = 0;
 	device_remove_file(&ne->device, &dev_attr_ne_in_limbo);
···
 		if (ud->ne != ne)
 			continue;
 
-		if (ud->device.driver && ud->device.driver->resume)
-			ud->device.driver->resume(&ud->device);
+		drv = get_driver(ud->device.driver);
+		if (!drv)
+			continue;
+
+		if (drv->resume) {
+			down(&ud->device.sem);
+			drv->resume(&ud->device);
+			up(&ud->device.sem);
+		}
+		put_driver(drv);
 	}
 	up(&nodemgr_ud_class.sem);
 
···
 
 static void nodemgr_update_pdrv(struct node_entry *ne)
 {
-	struct unit_directory *ud;
-	struct hpsb_protocol_driver *pdrv;
 	struct device *dev;
+	struct unit_directory *ud;
+	struct device_driver *drv;
+	struct hpsb_protocol_driver *pdrv;
+	int error;
 
 	down(&nodemgr_ud_class.sem);
 	list_for_each_entry(dev, &nodemgr_ud_class.devices, node) {
···
 		if (ud->ne != ne)
 			continue;
 
-		if (ud->device.driver) {
-			pdrv = container_of(ud->device.driver,
-					    struct hpsb_protocol_driver,
-					    driver);
-			if (pdrv->update && pdrv->update(ud))
-				device_release_driver(&ud->device);
+		drv = get_driver(ud->device.driver);
+		if (!drv)
+			continue;
+
+		error = 0;
+		pdrv = container_of(drv, struct hpsb_protocol_driver, driver);
+		if (pdrv->update) {
+			down(&ud->device.sem);
+			error = pdrv->update(ud);
+			up(&ud->device.sem);
 		}
+		if (error)
+			device_release_driver(&ud->device);
+		put_driver(drv);
 	}
 	up(&nodemgr_ud_class.sem);
 }
···
 		if (kthread_should_stop())
 			goto exit;
 
-		if (mutex_lock_interruptible(&nodemgr_serialize)) {
-			if (try_to_freeze())
-				continue;
-			goto exit;
-		}
-
 		/* Pause for 1/4 second in 1/16 second intervals,
 		 * to make sure things settle down. */
 		g = get_hpsb_generation(host);
 		for (i = 0; i < 4 ; i++) {
 			if (msleep_interruptible(63) || kthread_should_stop())
-				goto unlock_exit;
+				goto exit;
 
 			/* Now get the generation in which the node ID's we collect
 			 * are valid.  During the bus scan we will use this generation
···
 		if (!nodemgr_check_irm_capability(host, reset_cycles) ||
 		    !nodemgr_do_irm_duties(host, reset_cycles)) {
 			reset_cycles++;
-			mutex_unlock(&nodemgr_serialize);
 			continue;
 		}
 		reset_cycles = 0;
···
 
 		/* Update some of our sysfs symlinks */
 		nodemgr_update_host_dev_links(host);
-
-		mutex_unlock(&nodemgr_serialize);
 	}
-unlock_exit:
-	mutex_unlock(&nodemgr_serialize);
 exit:
 	HPSB_VERBOSE("NodeMgr: Exiting thread");
 	return 0;