From: Rob Evers <revers@redhat.com>
Date: Fri, 5 Feb 2010 16:42:49 -0500
Subject: [scsi] scsi_dh: change scsidh_activate interface to async
Message-id: <20100205164217.24469.23581.sendpatchset@localhost.localdomain>
Patchwork-id: 23153
O-Subject: [RHEL5.5 PATCH 1/2] scsi_dh: Change the scsidh_activate interface to
	be asynchronous
Bugzilla: 537514
RH-Acked-by: Tomas Henzl <thenzl@redhat.com>

https://bugzilla.redhat.com/show_bug.cgi?id=537514

From: Chandra Seetharaman <sekharan@us.ibm.com>
Date: Wed, 21 Oct 2009 16:22:46 +0000 (-0700)
Subject: [SCSI] scsi_dh: Change the scsidh_activate interface to be asynchronous
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fjejb%2Fscsi-misc-2.6.git;a=commitdiff_plain;h=d1c55de2d73e9cdc7b4839bf3b3dc2ca8c146605;hp=08d33e3de4d27f820724a12059360289fdd290d7

[SCSI] scsi_dh: Change the scsidh_activate interface to be asynchronous

Make scsi_dh_activate() function asynchronous, by taking in two additional
parameters, one is the callback function and the other is the data to call
the callback function with.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 5add1e2..d0494b9 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1172,8 +1172,9 @@ void dm_pg_init_complete(struct path *path, unsigned err_flags)
 	spin_unlock_irqrestore(&m->lock, flags);
 }
 
-static void pg_init_done(struct path *path, int errors)
+static void pg_init_done(void *data, int errors)
 {
+	struct path *path = data;
 	struct pgpath *pgpath = path_to_pgpath(path);
 	struct priority_group *pg = pgpath->pg;
 	struct multipath *m = pg->m;
@@ -1245,11 +1246,10 @@ static void pg_init_done(struct path *path, int errors)
 
 static void activate_path(void *data)
 {
-	int ret;
 	struct pgpath *pgpath = (struct pgpath *) data;
 
-	ret = scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev));
-	pg_init_done(&pgpath->path, ret);
+	scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
+				pg_init_done, &pgpath->path);
 }
 
 /*
diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c
index 1db3b4a..c10f1c7 100644
--- a/drivers/scsi/device_handler/scsi_dh.c
+++ b/drivers/scsi/device_handler/scsi_dh.c
@@ -218,7 +218,7 @@ store_dh_state(struct device *dev, struct device_attribute *attr,
 			 * Activate a device handler
 			 */
 			if (scsi_dh->activate)
-				err = scsi_dh->activate(sdev);
+				err = scsi_dh->activate(sdev, NULL, NULL);
 			else
 				err = 0;
 		}
@@ -416,10 +416,17 @@ EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
 /*
  * scsi_dh_activate - activate the path associated with the scsi_device
  *      corresponding to the given request queue.
- * @q - Request queue that is associated with the scsi_device to be
- *      activated.
+ *     Returns immediately without waiting for activation to be completed.
+ * @q    - Request queue that is associated with the scsi_device to be
+ *         activated.
+ * @fn   - Function to be called upon completion of the activation.
+ *         Function fn is called with data (below) and the error code.
+ *         Function fn may be called from the same calling context. So,
+ *         do not hold the lock in the caller which may be needed in fn.
+ * @data - data passed to the function fn upon completion.
+ *
  */
-int scsi_dh_activate(struct request_queue *q)
+int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *fn_data)
 {
 	int err = 0;
 	unsigned long flags;
@@ -439,7 +446,7 @@ int scsi_dh_activate(struct request_queue *q)
 		return err;
 
 	if (scsi_dh->activate)
-		err = scsi_dh->activate(sdev);
+		err = scsi_dh->activate(sdev, fn, fn_data);
 	put_device(&sdev->sdev_gendev);
 	return err;
 }
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 8ceec2a..1c16a40 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -654,7 +654,8 @@ out:
  * based on a certain policy. But until we actually encounter them it
  * should be okay.
  */
-static int alua_activate(struct scsi_device *sdev)
+static int alua_activate(struct scsi_device *sdev,
+			activate_complete fn, void *data)
 {
 	struct alua_dh_data *h = get_alua_data(sdev);
 	int err = SCSI_DH_OK;
@@ -669,7 +670,9 @@ static int alua_activate(struct scsi_device *sdev)
 		err = alua_stpg(sdev, TPGS_STATE_OPTIMIZED, h);
 
 out:
-	return err;
+	if (fn)
+		fn(data, err);
+	return 0;
 }
 
 /*
diff --git a/drivers/scsi/device_handler/scsi_dh_emc.c b/drivers/scsi/device_handler/scsi_dh_emc.c
index c4a7ffb..f7c3abe 100644
--- a/drivers/scsi/device_handler/scsi_dh_emc.c
+++ b/drivers/scsi/device_handler/scsi_dh_emc.c
@@ -531,7 +531,8 @@ retry:
 	return err;
 }
 
-static int clariion_activate(struct scsi_device *sdev)
+static int clariion_activate(struct scsi_device *sdev,
+				activate_complete fn, void *data)
 {
 	struct clariion_dh_data *csdev = get_clariion_data(sdev);
 	int result;
@@ -561,7 +562,9 @@ done:
 		    CLARIION_NAME, csdev->current_sp + 'A',
 		    csdev->port, lun_state[csdev->lun_state],
 		    csdev->default_sp + 'A');
-	return result;
+	if (fn)
+		fn(data, result);
+	return 0;
 }
 
 /*
diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c
index 5df8b1b..111a309 100644
--- a/drivers/scsi/device_handler/scsi_dh_rdac.c
+++ b/drivers/scsi/device_handler/scsi_dh_rdac.c
@@ -571,7 +571,8 @@ done:
 	return err;
 }
 
-static int rdac_activate(struct scsi_device *sdev)
+static int rdac_activate(struct scsi_device *sdev,
+			activate_complete fn, void *data)
 {
 	struct rdac_dh_data *h = get_rdac_data(sdev);
 	int err = SCSI_DH_OK;
@@ -583,7 +584,9 @@ static int rdac_activate(struct scsi_device *sdev)
 	if (h->lun_state == RDAC_LUN_UNOWNED)
 		err = send_mode_select(sdev, h);
 done:
-	return err;
+	if (fn)
+		fn(data, err);
+	return 0;
 }
 
 static int rdac_prep_fn(struct scsi_device *sdev, struct request *req)
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index fddaf3e..b8a74ae 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -177,6 +177,7 @@ struct scsi_device_dh_data {
 	unsigned long		sdev_data[0];
 } __attribute__((aligned(sizeof(unsigned long))));
 
+typedef void (*activate_complete)(void *, int);
 struct scsi_device_handler {
 	/* Used by the infrastructure */
 	struct list_head list; /* list of scsi_device_handlers */
@@ -188,7 +189,7 @@ struct scsi_device_handler {
 	int (*check_sense)(struct scsi_device *, struct scsi_sense_hdr *);
 	int (*attach)(struct scsi_device *);
 	void (*detach)(struct scsi_device *);
-	int (*activate)(struct scsi_device *);
+	int (*activate)(struct scsi_device *, activate_complete, void *);
 	int (*prep_fn)(struct scsi_device *, struct request *);
 	int (*set_params)(struct scsi_device *, const char *);
 };
diff --git a/include/scsi/scsi_dh.h b/include/scsi/scsi_dh.h
index b3e7da5..2c12261 100644
--- a/include/scsi/scsi_dh.h
+++ b/include/scsi/scsi_dh.h
@@ -61,14 +61,16 @@ extern void store_scsi_dh_data(struct scsi_device *, struct scsi_dh_data *);
 extern struct scsi_dh_data *retrieve_scsi_dh_data(struct scsi_device *);
 
 #if defined(CONFIG_SCSI_DH) || defined(CONFIG_SCSI_DH_MODULE)
-extern int scsi_dh_activate(struct request_queue *);
+extern int scsi_dh_activate(struct request_queue *, activate_complete, void *);
 extern int scsi_dh_handler_exist(const char *);
 extern int scsi_dh_attach(struct request_queue *, const char *);
 extern void scsi_dh_detach(struct request_queue *);
 extern int scsi_dh_set_params(struct request_queue *, const char *);
 #else
-static inline int scsi_dh_activate(struct request_queue *req)
+static inline int scsi_dh_activate(struct request_queue *req,
+					activate_complete fn, void *data)
 {
+	fn(data, 0);
 	return 0;
 }
 static inline int scsi_dh_handler_exist(const char *name)