virtio-blk: drop config_mutex

config_mutex served two purposes: prevent multiple concurrent config
change handlers, and synchronize access to config_enable flag.

Since commit dbf2576e37da0fcc7aacbfbb9fd5d3de7888a3c1
    workqueue: make all workqueues non-reentrant
all workqueues are non-reentrant, and config_enable
is now gone.

Get rid of the unnecessary lock.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 91272f1..89ba8d6 100644 (file)
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -41,9 +41,6 @@ struct virtio_blk
        /* Process context for config space updates */
        struct work_struct config_work;
 
-       /* Lock for config space updates */
-       struct mutex config_lock;
-
        /* What host tells us, plus 2 for header & tailer. */
        unsigned int sg_elems;
 
@@ -344,8 +341,6 @@ static void virtblk_config_changed_work(struct work_struct *work)
        char *envp[] = { "RESIZE=1", NULL };
        u64 capacity, size;
 
-       mutex_lock(&vblk->config_lock);
-
        /* Host must always specify the capacity. */
        virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
 
@@ -369,8 +364,6 @@ static void virtblk_config_changed_work(struct work_struct *work)
        set_capacity(vblk->disk, capacity);
        revalidate_disk(vblk->disk);
        kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
-
-       mutex_unlock(&vblk->config_lock);
 }
 
 static void virtblk_config_changed(struct virtio_device *vdev)
@@ -601,7 +594,6 @@ static int virtblk_probe(struct virtio_device *vdev)
 
        vblk->vdev = vdev;
        vblk->sg_elems = sg_elems;
-       mutex_init(&vblk->config_lock);
 
        INIT_WORK(&vblk->config_work, virtblk_config_changed_work);