Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

[linux-2.6-microblaze.git] / block / blk-sysfs.c

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 870484e..cbea895 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -853,6 +853,10 @@ struct kobj_type blk_queue_ktype = {
        .release        = blk_release_queue,
 };
 
+/**
+ * blk_register_queue - register a block layer queue with sysfs
+ * @disk: Disk of which the request queue should be registered with sysfs.
+ */
 int blk_register_queue(struct gendisk *disk)
 {
        int ret;
@@ -909,11 +913,12 @@ int blk_register_queue(struct gendisk *disk)
        if (q->request_fn || (q->mq_ops && q->elevator)) {
                ret = elv_register_queue(q);
                if (ret) {
+                       mutex_unlock(&q->sysfs_lock);
                        kobject_uevent(&q->kobj, KOBJ_REMOVE);
                        kobject_del(&q->kobj);
                        blk_trace_remove_sysfs(dev);
                        kobject_put(&dev->kobj);
-                       goto unlock;
+                       return ret;
                }
        }
        ret = 0;
@@ -921,7 +926,15 @@ unlock:
        mutex_unlock(&q->sysfs_lock);
        return ret;
 }
+EXPORT_SYMBOL_GPL(blk_register_queue);
 
+/**
+ * blk_unregister_queue - counterpart of blk_register_queue()
+ * @disk: Disk of which the request queue should be unregistered from sysfs.
+ *
+ * Note: the caller is responsible for guaranteeing that this function is called
+ * after blk_register_queue() has finished.
+ */
 void blk_unregister_queue(struct gendisk *disk)
 {
        struct request_queue *q = disk->queue;
@@ -929,21 +942,39 @@ void blk_unregister_queue(struct gendisk *disk)
        if (WARN_ON(!q))
                return;
 
-       mutex_lock(&q->sysfs_lock);
-       queue_flag_clear_unlocked(QUEUE_FLAG_REGISTERED, q);
-       mutex_unlock(&q->sysfs_lock);
+       /* Return early if disk->queue was never registered. */
+       if (!test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags))
+               return;
 
-       wbt_exit(q);
+       /*
+        * Since sysfs_remove_dir() prevents adding new directory entries
+        * before removal of existing entries starts, protect against
+        * concurrent elv_iosched_store() calls.
+        */
+       mutex_lock(&q->sysfs_lock);
 
+       spin_lock_irq(q->queue_lock);
+       queue_flag_clear(QUEUE_FLAG_REGISTERED, q);
+       spin_unlock_irq(q->queue_lock);
 
+       /*
+        * Remove the sysfs attributes before unregistering the queue data
+        * structures that can be modified through sysfs.
+        */
        if (q->mq_ops)
                blk_mq_unregister_dev(disk_to_dev(disk), q);
-
-       if (q->request_fn || (q->mq_ops && q->elevator))
-               elv_unregister_queue(q);
+       mutex_unlock(&q->sysfs_lock);
 
        kobject_uevent(&q->kobj, KOBJ_REMOVE);
        kobject_del(&q->kobj);
        blk_trace_remove_sysfs(disk_to_dev(disk));
+
+       wbt_exit(q);
+
+       mutex_lock(&q->sysfs_lock);
+       if (q->request_fn || (q->mq_ops && q->elevator))
+               elv_unregister_queue(q);
+       mutex_unlock(&q->sysfs_lock);
+
        kobject_put(&disk_to_dev(disk)->kobj);
 }