block: allow gendisk's request_queue registration to be deferred

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

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 870484eaed1f64b586ccb0fd4dd34c3f9462a29d..4a6a40ffd78e7433e5ce323934966cde52795ed9 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -921,6 +921,7 @@ unlock:
        mutex_unlock(&q->sysfs_lock);
        return ret;
 }
+EXPORT_SYMBOL_GPL(blk_register_queue);
 
 void blk_unregister_queue(struct gendisk *disk)
 {
@@ -929,12 +930,21 @@ void blk_unregister_queue(struct gendisk *disk)
        if (WARN_ON(!q))
                return;
 
+       /* Return early if disk->queue was never registered. */
+       if (!test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags))
+               return;
+
+       /*
+        * Protect against the 'queue' kobj being accessed
+        * while/after it is removed.
+        */
        mutex_lock(&q->sysfs_lock);
-       queue_flag_clear_unlocked(QUEUE_FLAG_REGISTERED, q);
-       mutex_unlock(&q->sysfs_lock);
 
-       wbt_exit(q);
+       spin_lock_irq(q->queue_lock);
+       queue_flag_clear(QUEUE_FLAG_REGISTERED, q);
+       spin_unlock_irq(q->queue_lock);
 
+       wbt_exit(q);
 
        if (q->mq_ops)
                blk_mq_unregister_dev(disk_to_dev(disk), q);
@@ -946,4 +956,6 @@ void blk_unregister_queue(struct gendisk *disk)
        kobject_del(&q->kobj);
        blk_trace_remove_sysfs(disk_to_dev(disk));
        kobject_put(&disk_to_dev(disk)->kobj);
+
+       mutex_unlock(&q->sysfs_lock);
 }