[PATCH] scsi-misc-2.5 remove scsi_device list_lock (take 2)

[Patrick Mansfield <patmans@us.ibm.com>]

Revised patch (against scsi-misc-2.5) based on comments to use the
sdev->sdev_lock instead of the sdev->list_lock.

diff -purN -X /home/patman/dontdiff 2.5-cur/drivers/scsi/dpt_i2o.c rmcmd_lock-2.5-cur/drivers/scsi/dpt_i2o.c
--- 2.5-cur/drivers/scsi/dpt_i2o.c	Tue May  6 16:22:34 2003
+++ rmcmd_lock-2.5-cur/drivers/scsi/dpt_i2o.c	Tue May  6 17:23:14 2003
@@ -2510,7 +2510,7 @@ static void adpt_fail_posted_scbs(adpt_h
 
 	list_for_each_entry(d, &pHba->host->my_devices, siblings) {
 		unsigned long flags;
-		spin_lock_irqsave(&d->list_lock, flags);
+		spin_lock_irqsave(&d->sdev_lock, flags);
 		list_for_each_entry(cmd, &d->cmd_list, list) {
 			if(cmd->serial_number == 0){
 				continue;
@@ -2518,7 +2518,7 @@ static void adpt_fail_posted_scbs(adpt_h
 			cmd->result = (DID_OK << 16) | (QUEUE_FULL <<1);
 			cmd->scsi_done(cmd);
 		}
-		spin_unlock_irqrestore(&d->list_lock, flags);
+		spin_unlock_irqrestore(&d->sdev_lock, flags);
 	}
 }
 
diff -purN -X /home/patman/dontdiff 2.5-cur/drivers/scsi/hosts.c rmcmd_lock-2.5-cur/drivers/scsi/hosts.c
--- 2.5-cur/drivers/scsi/hosts.c	Tue May  6 16:22:34 2003
+++ rmcmd_lock-2.5-cur/drivers/scsi/hosts.c	Tue May  6 17:23:14 2003
@@ -204,7 +204,7 @@ static int scsi_check_device_busy(struct
 	 * device.  If any of them are busy, then set the state
 	 * back to inactive and bail.
 	 */
-	spin_lock_irqsave(&sdev->list_lock, flags);
+	spin_lock_irqsave(&sdev->sdev_lock, flags);
 	list_for_each_entry(scmd, &sdev->cmd_list, list) {
 		if (scmd->request && scmd->request->rq_status != RQ_INACTIVE)
 			goto active;
@@ -217,7 +217,7 @@ static int scsi_check_device_busy(struct
 		if (scmd->request)
 			scmd->request->rq_status = RQ_SCSI_DISCONNECTING;
 	}
-	spin_unlock_irqrestore(&sdev->list_lock, flags);
+	spin_unlock_irqrestore(&sdev->sdev_lock, flags);
 
 	return 0;
 
@@ -234,7 +234,7 @@ active:
 		}
 	}
 
-	spin_unlock_irqrestore(&sdev->list_lock, flags);
+	spin_unlock_irqrestore(&sdev->sdev_lock, flags);
 	printk(KERN_ERR "Device busy???\n");
 	return 1;
 }
diff -purN -X /home/patman/dontdiff 2.5-cur/drivers/scsi/scsi.c rmcmd_lock-2.5-cur/drivers/scsi/scsi.c
--- 2.5-cur/drivers/scsi/scsi.c	Tue Apr 29 12:24:04 2003
+++ rmcmd_lock-2.5-cur/drivers/scsi/scsi.c	Tue May  6 17:23:14 2003
@@ -219,8 +219,8 @@ static struct scsi_host_cmd_pool scsi_cm
 
 static DECLARE_MUTEX(host_cmd_pool_mutex);
 
-static struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost,
-					    int gfp_mask)
+static struct scsi_cmnd *scsi_alloc_cmd(struct Scsi_Host *shost,
+					       int gfp_mask)
 {
 	struct scsi_cmnd *cmd;
 
@@ -242,71 +242,114 @@ static struct scsi_cmnd *__scsi_get_comm
 	return cmd;
 }
 
-/*
- * Function:	scsi_get_command()
- *
- * Purpose:	Allocate and setup a scsi command block
- *
- * Arguments:	dev	- parent scsi device
- *		gfp_mask- allocator flags
- *
- * Returns:	The allocated scsi command structure.
- */
-struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, int gfp_mask)
+static void scsi_init_cmd(struct scsi_device *dev, struct scsi_cmnd *cmd)
 {
-	struct scsi_cmnd *cmd = __scsi_get_command(dev->host, gfp_mask);
-
 	if (likely(cmd != NULL)) {
-		unsigned long flags;
-
 		memset(cmd, 0, sizeof(*cmd));
 		cmd->device = dev;
 		cmd->state = SCSI_STATE_UNUSED;
 		cmd->owner = SCSI_OWNER_NOBODY;
 		init_timer(&cmd->eh_timeout);
 		INIT_LIST_HEAD(&cmd->list);
-		spin_lock_irqsave(&dev->list_lock, flags);
 		list_add_tail(&cmd->list, &dev->cmd_list);
-		spin_unlock_irqrestore(&dev->list_lock, flags);
 	}
+}
+
+/*
+ * Function:	__scsi_get_command()
+ *
+ * Purpose:	Allocate and setup a scsi command block. This function is
+ * 		extern but not exported outside of scsi.
+ *
+ * Arguments:	dev	- parent scsi device
+ *		gfp_mask- allocator flags
+ *
+ * Locks:	Called with sdev_lock held.
+ *
+ * Returns:	The allocated scsi command structure.
+ */
+struct scsi_cmnd *__scsi_get_command(struct scsi_device *dev, int gfp_mask)
+{
+	struct scsi_cmnd *cmd = scsi_alloc_cmd(dev->host, gfp_mask);
 
+	scsi_init_cmd(dev, cmd);
 	return cmd;
 }				
 
 /*
- * Function:	scsi_put_command()
+ * Function:	scsi_get_command()
+ *
+ * Purpose:	Allocate and setup a scsi command block. This function is
+ * 		exported.
+ *
+ * Arguments:	dev	- parent scsi device
+ *		gfp_mask- allocator flags
+ *
+ * Returns:	Nothing.
+ */
+struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, int gfp_mask)
+{
+	struct scsi_cmnd *cmd = scsi_alloc_cmd(dev->host, gfp_mask);
+	unsigned long flags;
+	
+	spin_lock_irqsave(&dev->sdev_lock, flags);
+	scsi_init_cmd(dev, cmd);
+	spin_unlock_irqrestore(&dev->sdev_lock, flags);
+	return cmd;
+}
+
+/*
+ * Function:	__scsi_put_command()
  *
- * Purpose:	Free a scsi command block
+ * Purpose:	Free a scsi command block. This function is extern but not
+ * 		exported outside of scsi.
  *
  * Arguments:	cmd	- command block to free
  *
  * Returns:	Nothing.
  *
+ * Locks:	Called with sdev_lock held.
+ *
  * Notes:	The command must not belong to any lists.
  */
-void scsi_put_command(struct scsi_cmnd *cmd)
+void __scsi_put_command(struct scsi_cmnd *cmd)
 {
 	struct Scsi_Host *shost = cmd->device->host;
-	unsigned long flags;
 	
 	/* serious error if the command hasn't come from a device list */
-	spin_lock_irqsave(&cmd->device->list_lock, flags);
 	BUG_ON(list_empty(&cmd->list));
 	list_del_init(&cmd->list);
-	spin_unlock(&cmd->device->list_lock);
-	/* changing locks here, don't need to restore the irq state */
 	spin_lock(&shost->free_list_lock);
 	if (unlikely(list_empty(&shost->free_list))) {
 		list_add(&cmd->list, &shost->free_list);
 		cmd = NULL;
 	}
-	spin_unlock_irqrestore(&shost->free_list_lock, flags);
+	spin_unlock(&shost->free_list_lock);
 
 	if (likely(cmd != NULL))
 		kmem_cache_free(shost->cmd_pool->slab, cmd);
 }
 
 /*
+ * Function:	scsi_put_command()
+ *
+ * Purpose:	Free a scsi command block. This function is exported.
+ *
+ * Arguments:	cmd	- command block to free
+ *
+ * Returns:	Nothing.
+ */
+void scsi_put_command(struct scsi_cmnd *cmd)
+{
+	struct scsi_device *sdev = cmd->device;
+	unsigned long flags;
+	
+	spin_lock_irqsave(&sdev->sdev_lock, flags);
+	__scsi_put_command(cmd);
+	spin_unlock_irqrestore(&sdev->sdev_lock, flags);
+}
+
+/*
  * Function:	scsi_setup_command_freelist()
  *
  * Purpose:	Setup the command freelist for a scsi host.
@@ -1240,7 +1283,7 @@ void scsi_device_put(struct scsi_device 
  * scsi_set_device_offline - set scsi_device offline
  * @sdev:	pointer to struct scsi_device to offline. 
  *
- * Locks:	host_lock held on entry.
+ * Locks:	No scsi locks should be held on entry.
  **/
 void scsi_set_device_offline(struct scsi_device *sdev)
 {
@@ -1251,7 +1294,7 @@ void scsi_set_device_offline(struct scsi
 
 	sdev->online = 0;
 
-	spin_lock_irqsave(&sdev->list_lock, flags);
+	spin_lock_irqsave(&sdev->sdev_lock, flags);
 	list_for_each_entry(scmd, &sdev->cmd_list, list) {
 		if (scmd->request && scmd->request->rq_status != RQ_INACTIVE) {
 			/*
@@ -1264,7 +1307,7 @@ void scsi_set_device_offline(struct scsi
 			list_add_tail(&scmd->eh_entry, &active_list);
 		}
 	}
-	spin_unlock_irqrestore(&sdev->list_lock, flags);
+	spin_unlock_irqrestore(&sdev->sdev_lock, flags);
 
 	if (!list_empty(&active_list)) {
 		list_for_each_safe(lh, lh_sf, &active_list) {
diff -purN -X /home/patman/dontdiff 2.5-cur/drivers/scsi/scsi.h rmcmd_lock-2.5-cur/drivers/scsi/scsi.h
--- 2.5-cur/drivers/scsi/scsi.h	Tue Apr 29 11:14:15 2003
+++ rmcmd_lock-2.5-cur/drivers/scsi/scsi.h	Tue May  6 17:23:14 2003
@@ -327,7 +327,6 @@ struct scsi_device {
 	request_queue_t *request_queue;
 	volatile unsigned short device_busy;	/* commands actually active on low-level */
 	spinlock_t sdev_lock;           /* also the request queue_lock */
-	spinlock_t list_lock;
 	struct list_head cmd_list;	/* queue of in use SCSI Command structures */
 	struct list_head starved_entry;
         Scsi_Cmnd *current_cmnd;	/* currently active command */
diff -purN -X /home/patman/dontdiff 2.5-cur/drivers/scsi/scsi_lib.c rmcmd_lock-2.5-cur/drivers/scsi/scsi_lib.c
--- 2.5-cur/drivers/scsi/scsi_lib.c	Tue Apr 29 11:14:15 2003
+++ rmcmd_lock-2.5-cur/drivers/scsi/scsi_lib.c	Tue May  6 17:23:14 2003
@@ -528,13 +528,13 @@ static struct scsi_cmnd *scsi_end_reques
 	if (blk_rq_tagged(req))
 		blk_queue_end_tag(q, req);
 	end_that_request_last(req);
+	__scsi_put_command(cmd);
 	spin_unlock_irqrestore(q->queue_lock, flags);
 
 	/*
 	 * This will goose the queue request function at the end, so we don't
 	 * need to worry about launching another command.
 	 */
-	scsi_put_command(cmd);
 	scsi_queue_next_request(q, NULL);
 	return NULL;
 }
@@ -950,7 +950,7 @@ static int scsi_init_io(struct scsi_cmnd
 			req->current_nr_sectors);
 
 	/* release the command and kill it */
-	scsi_put_command(cmd);
+	__scsi_put_command(cmd);
 	return BLKPREP_KILL;
 }
 
@@ -974,7 +974,7 @@ static int scsi_prep_fn(struct request_q
 		struct scsi_request *sreq = req->special;
 
 		if (sreq->sr_magic == SCSI_REQ_MAGIC) {
-			cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC);
+			cmd = __scsi_get_command(sreq->sr_device, GFP_ATOMIC);
 			if (unlikely(!cmd))
 				goto defer;
 			scsi_init_cmd_from_req(cmd, sreq);
@@ -985,7 +985,7 @@ static int scsi_prep_fn(struct request_q
 		 * Now try and find a command block that we can use.
 		 */
 		if (!req->special) {
-			cmd = scsi_get_command(sdev, GFP_ATOMIC);
+			cmd = __scsi_get_command(sdev, GFP_ATOMIC);
 			if (unlikely(!cmd))
 				goto defer;
 		} else
@@ -1006,10 +1006,10 @@ static int scsi_prep_fn(struct request_q
 	
 	/*
 	 * FIXME: drop the lock here because the functions below
-	 * expect to be called without the queue lock held.  Also,
-	 * previously, we dequeued the request before dropping the
-	 * lock.  We hope REQ_STARTED prevents anything untoward from
-	 * happening now.
+	 * expect to be called without the queue lock held (except
+	 * __scsi_put_command). Also, previously, we dequeued the request
+	 * before dropping the lock. We hope REQ_STARTED prevents
+	 * anything untoward from happening now.
 	 */
 	if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
 		int ret;
@@ -1042,7 +1042,7 @@ static int scsi_prep_fn(struct request_q
 		 */
 		if (unlikely(!sdt->init_command(cmd))) {
 			scsi_release_buffers(cmd);
-			scsi_put_command(cmd);
+			__scsi_put_command(cmd);
 			return BLKPREP_KILL;
 		}
 	}
diff -purN -X /home/patman/dontdiff 2.5-cur/drivers/scsi/scsi_priv.h rmcmd_lock-2.5-cur/drivers/scsi/scsi_priv.h
--- 2.5-cur/drivers/scsi/scsi_priv.h	Tue Apr 29 12:24:04 2003
+++ rmcmd_lock-2.5-cur/drivers/scsi/scsi_priv.h	Tue May  6 17:23:14 2003
@@ -61,6 +61,8 @@ extern void scsi_host_init(void);
 
 /* scsi.c */
 extern int scsi_dispatch_cmd(struct scsi_cmnd *cmd);
+extern struct scsi_cmnd *__scsi_get_command(struct scsi_device *dev, int flags);
+extern void __scsi_put_command(struct scsi_cmnd *cmd);
 extern int scsi_setup_command_freelist(struct Scsi_Host *shost);
 extern void scsi_destroy_command_freelist(struct Scsi_Host *shost);
 extern void scsi_done(struct scsi_cmnd *cmd);
diff -purN -X /home/patman/dontdiff 2.5-cur/drivers/scsi/scsi_scan.c rmcmd_lock-2.5-cur/drivers/scsi/scsi_scan.c
--- 2.5-cur/drivers/scsi/scsi_scan.c	Tue May  6 16:22:34 2003
+++ rmcmd_lock-2.5-cur/drivers/scsi/scsi_scan.c	Tue May  6 17:23:14 2003
@@ -408,7 +408,6 @@ static struct scsi_device *scsi_alloc_sd
 	INIT_LIST_HEAD(&sdev->same_target_siblings);
 	INIT_LIST_HEAD(&sdev->cmd_list);
 	INIT_LIST_HEAD(&sdev->starved_entry);
-	spin_lock_init(&sdev->list_lock);
 
 	/*
 	 * Some low level driver could use device->type