scsi: Protect SCSI device state changes with a mutex
Serializing SCSI device state changes avoids that two state changes can
occur concurrently, e.g. the state changes in scsi_target_block() and
__scsi_remove_device(). This serialization is essential to make patch
"Make __scsi_remove_device go straight from BLOCKED to DEL" work
reliably.
Enable this mechanism for all scsi_target_*block() callers but not for
the scsi_internal_device_unblock() calls from the mpt3sas driver because
that driver can call scsi_internal_device_unblock() from atomic context.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f0eb557..4b0bac3 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2882,7 +2882,12 @@ static void scsi_wait_for_queuecommand(struct scsi_device *sdev)
int
scsi_device_quiesce(struct scsi_device *sdev)
{
- int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
+ int err;
+
+ mutex_lock(&sdev->state_mutex);
+ err = scsi_device_set_state(sdev, SDEV_QUIESCE);
+ mutex_unlock(&sdev->state_mutex);
+
if (err)
return err;
@@ -2910,10 +2915,11 @@ void scsi_device_resume(struct scsi_device *sdev)
* so assume the state is being managed elsewhere (for example
* device deleted during suspend)
*/
- if (sdev->sdev_state != SDEV_QUIESCE ||
- scsi_device_set_state(sdev, SDEV_RUNNING))
- return;
- scsi_run_queue(sdev->request_queue);
+ mutex_lock(&sdev->state_mutex);
+ if (sdev->sdev_state == SDEV_QUIESCE &&
+ scsi_device_set_state(sdev, SDEV_RUNNING) == 0)
+ scsi_run_queue(sdev->request_queue);
+ mutex_unlock(&sdev->state_mutex);
}
EXPORT_SYMBOL(scsi_device_resume);
@@ -3012,6 +3018,7 @@ static int scsi_internal_device_block(struct scsi_device *sdev)
struct request_queue *q = sdev->request_queue;
int err;
+ mutex_lock(&sdev->state_mutex);
err = scsi_internal_device_block_nowait(sdev);
if (err == 0) {
if (q->mq_ops)
@@ -3019,6 +3026,8 @@ static int scsi_internal_device_block(struct scsi_device *sdev)
else
scsi_wait_for_queuecommand(sdev);
}
+ mutex_unlock(&sdev->state_mutex);
+
return err;
}
@@ -3089,7 +3098,13 @@ EXPORT_SYMBOL_GPL(scsi_internal_device_unblock_nowait);
static int scsi_internal_device_unblock(struct scsi_device *sdev,
enum scsi_device_state new_state)
{
- return scsi_internal_device_unblock_nowait(sdev, new_state);
+ int ret;
+
+ mutex_lock(&sdev->state_mutex);
+ ret = scsi_internal_device_unblock_nowait(sdev, new_state);
+ mutex_unlock(&sdev->state_mutex);
+
+ return ret;
}
static void