[SCSI] rework scsi_target allocation

The current target allocation code registeres each possible target
with sysfs; it will be deleted again if no useable LUN on this target
was found. This results in a string of 'target add/target remove' uevents.

Based on a patch by Hannes Reinecke <hare@suse.de> this patch reworks
the target allocation code so that only uevents for existing targets
are sent. The sysfs registration is split off from the existing
scsi_target_alloc() into a in a new scsi_add_target() function, which
should be called whenever an existing target is found. Only then a
uevent is sent, so we'll be generating events for existing targets
only.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

3 files changed, 63 insertions, 39 deletions

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index e1644b270cdc..fcd7455ffc39 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -322,6 +322,21 @@ out:
         return NULL;
 }
 
+static void scsi_target_destroy(struct scsi_target *starget)
+{
+        struct device *dev = &starget->dev;
+        struct Scsi_Host *shost = dev_to_shost(dev->parent);
+        unsigned long flags;
+
+        transport_destroy_device(dev);
+        spin_lock_irqsave(shost->host_lock, flags);
+        if (shost->hostt->target_destroy)
+                shost->hostt->target_destroy(starget);
+        list_del_init(&starget->siblings);
+        spin_unlock_irqrestore(shost->host_lock, flags);
+        put_device(dev);
+}
+
 static void scsi_target_dev_release(struct device *dev)
 {
         struct device *parent = dev->parent;
@@ -406,7 +421,7 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
         starget->channel = channel;
         INIT_LIST_HEAD(&starget->siblings);
         INIT_LIST_HEAD(&starget->devices);
-        starget->state = STARGET_RUNNING;
+        starget->state = STARGET_CREATED;
         starget->scsi_level = SCSI_2;
  retry:
         spin_lock_irqsave(shost->host_lock, flags);
@@ -419,18 +434,6 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
         spin_unlock_irqrestore(shost->host_lock, flags);
         /* allocate and add */
         transport_setup_device(dev);
-        error = device_add(dev);
-        if (error) {
-                dev_err(dev, "target device_add failed, error %d\n", error);
-                spin_lock_irqsave(shost->host_lock, flags);
-                list_del_init(&starget->siblings);
-                spin_unlock_irqrestore(shost->host_lock, flags);
-                transport_destroy_device(dev);
-                put_device(parent);
-                kfree(starget);
-                return NULL;
-        }
-        transport_add_device(dev);
         if (shost->hostt->target_alloc) {
                 error = shost->hostt->target_alloc(starget);
 
@@ -438,9 +441,7 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
                         dev_printk(KERN_ERR, dev, "target allocation failed, error %d\n", error);
                         /* don't want scsi_target_reap to do the final
                          * put because it will be under the host lock */
-                        get_device(dev);
-                        scsi_target_reap(starget);
-                        put_device(dev);
+                        scsi_target_destroy(starget);
                         return NULL;
                 }
         }
@@ -467,18 +468,10 @@ static void scsi_target_reap_usercontext(struct work_struct *work)
 {
         struct scsi_target *starget =
                 container_of(work, struct scsi_target, ew.work);
-        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
-        unsigned long flags;
 
         transport_remove_device(&starget->dev);
         device_del(&starget->dev);
-        transport_destroy_device(&starget->dev);
-        spin_lock_irqsave(shost->host_lock, flags);
-        if (shost->hostt->target_destroy)
-                shost->hostt->target_destroy(starget);
-        list_del_init(&starget->siblings);
-        spin_unlock_irqrestore(shost->host_lock, flags);
-        put_device(&starget->dev);
+        scsi_target_destroy(starget);
 }
 
 /**
@@ -493,21 +486,25 @@ void scsi_target_reap(struct scsi_target *starget)
 {
         struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
         unsigned long flags;
+        enum scsi_target_state state;
+        int empty;
 
         spin_lock_irqsave(shost->host_lock, flags);
+        state = starget->state;
+        empty = --starget->reap_ref == 0 &&
+                list_empty(&starget->devices) ? 1 : 0;
+        spin_unlock_irqrestore(shost->host_lock, flags);
 
-        if (--starget->reap_ref == 0 && list_empty(&starget->devices)) {
-                BUG_ON(starget->state == STARGET_DEL);
-                starget->state = STARGET_DEL;
-                spin_unlock_irqrestore(shost->host_lock, flags);
-                execute_in_process_context(scsi_target_reap_usercontext,
-                                           &starget->ew);
+        if (!empty)
                 return;
 
-        }
-        spin_unlock_irqrestore(shost->host_lock, flags);
-
-        return;
+        BUG_ON(state == STARGET_DEL);
+        starget->state = STARGET_DEL;
+        if (state == STARGET_CREATED)
+                scsi_target_destroy(starget);
+        else
+                execute_in_process_context(scsi_target_reap_usercontext,
+                                           &starget->ew);
 }
 
 /**
@@ -1056,8 +1053,9 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
                                         scsi_inq_str(vend, result, 8, 16),
                                         scsi_inq_str(mod, result, 16, 32));
                         });
+
                 }
-                
+
                 res = SCSI_SCAN_TARGET_PRESENT;
                 goto out_free_result;
         }
@@ -1497,7 +1495,6 @@ struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
         if (scsi_host_scan_allowed(shost))
                 scsi_probe_and_add_lun(starget, lun, NULL, &sdev, 1, hostdata);
         mutex_unlock(&shost->scan_mutex);
-        transport_configure_device(&starget->dev);
         scsi_target_reap(starget);
         put_device(&starget->dev);
 
@@ -1578,7 +1575,6 @@ static void __scsi_scan_target(struct device *parent, unsigned int channel,
  out_reap:
         /* now determine if the target has any children at all
          * and if not, nuke it */
-        transport_configure_device(&starget->dev);
         scsi_target_reap(starget);
 
         put_device(&starget->dev);
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 84e2a8ad83c9..198aa4571e35 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -809,6 +809,27 @@ sdev_store_queue_type_rw(struct device *dev, struct device_attribute *attr,
         return count;
 }
 
+static int scsi_target_add(struct scsi_target *starget)
+{
+        int error;
+
+        if (starget->state != STARGET_CREATED)
+                return 0;
+
+        error = device_add(&starget->dev);
+        if (error) {
+                dev_err(&starget->dev, "target device_add failed, error %d\n", error);
+                get_device(&starget->dev);
+                scsi_target_reap(starget);
+                put_device(&starget->dev);
+                return error;
+        }
+        transport_add_device(&starget->dev);
+        starget->state = STARGET_RUNNING;
+
+        return 0;
+}
+
 static struct device_attribute sdev_attr_queue_type_rw =
         __ATTR(queue_type, S_IRUGO | S_IWUSR, show_queue_type_field,
                sdev_store_queue_type_rw);
@@ -824,10 +845,16 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
 {
         int error, i;
         struct request_queue *rq = sdev->request_queue;
+        struct scsi_target *starget = sdev->sdev_target;
 
         if ((error = scsi_device_set_state(sdev, SDEV_RUNNING)) != 0)
                 return error;
 
+        error = scsi_target_add(starget);
+        if (error)
+                return error;
+
+        transport_configure_device(&starget->dev);
         error = device_add(&sdev->sdev_gendev);
         if (error) {
                 put_device(sdev->sdev_gendev.parent);
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index b8b19e2f57bb..f6a9fe0ef09c 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -181,7 +181,8 @@ struct scsi_device {
         sdev_printk(prefix, (scmd)->device, fmt, ##a)
 
 enum scsi_target_state {
-        STARGET_RUNNING = 1,
+        STARGET_CREATED = 1,
+        STARGET_RUNNING,
         STARGET_DEL,
 };