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_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 82dfe07..a91537a 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -719,7 +719,7 @@
store_state_field(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
- int i;
+ int i, ret;
struct scsi_device *sdev = to_scsi_device(dev);
enum scsi_device_state state = 0;
@@ -734,9 +734,11 @@
if (!state)
return -EINVAL;
- if (scsi_device_set_state(sdev, state))
- return -EINVAL;
- return count;
+ mutex_lock(&sdev->state_mutex);
+ ret = scsi_device_set_state(sdev, state);
+ mutex_unlock(&sdev->state_mutex);
+
+ return ret == 0 ? count : -EINVAL;
}
static ssize_t
@@ -1272,6 +1274,7 @@
void __scsi_remove_device(struct scsi_device *sdev)
{
struct device *dev = &sdev->sdev_gendev;
+ int res;
/*
* This cleanup path is not reentrant and while it is impossible
@@ -1282,7 +1285,15 @@
return;
if (sdev->is_visible) {
- if (scsi_device_set_state(sdev, SDEV_CANCEL) != 0)
+ /*
+ * If scsi_internal_target_block() is running concurrently,
+ * wait until it has finished before changing the device state.
+ */
+ mutex_lock(&sdev->state_mutex);
+ res = scsi_device_set_state(sdev, SDEV_CANCEL);
+ mutex_unlock(&sdev->state_mutex);
+
+ if (res != 0)
return;
bsg_unregister_queue(sdev->request_queue);
@@ -1298,7 +1309,10 @@
* scsi_run_queue() invocations have finished before tearing down the
* device.
*/
+ mutex_lock(&sdev->state_mutex);
scsi_device_set_state(sdev, SDEV_DEL);
+ mutex_unlock(&sdev->state_mutex);
+
blk_cleanup_queue(sdev->request_queue);
cancel_work_sync(&sdev->requeue_work);