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scsi: Avoid that .queuecommand() gets called for a blocked SCSI device

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Several SCSI transport and LLD drivers surround code that does not
tolerate concurrent calls of .queuecommand() with scsi_target_block() /
scsi_target_unblock(). These last two functions use
blk_mq_quiesce_queue() / blk_mq_unquiesce_queue() for scsi-mq request
queues to prevent concurrent .queuecommand() calls. However, that is
not sufficient to prevent .queuecommand() calls from scsi_send_eh_cmnd().
Hence surround the .queuecommand() call from the SCSI error handler with
code that avoids that .queuecommand() gets called in the blocked state.

Note: converting the .queuecommand() call in scsi_send_eh_cmnd() into
code that calls blk_get_request() + blk_execute_rq() is not an option
since scsi_send_eh_cmnd() must be able to make forward progress even
if all requests have been allocated.

Cc: Ming Lei <[email protected]>
Cc: Hannes Reinecke <[email protected]>
Cc: Johannes Thumshirn <[email protected]>
Signed-off-by: Bart Van Assche <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>
This commit is contained in:
Bart Van Assche authored and Martin K. Petersen committed 2019-06-20 15:37:02 -04:00
1 parent ac88c1f673
commit bbe9fb0d04
2 files changed
+24 -6
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drivers/scsi/scsi_error.c
+24 -2
View File
@@ -1055,7 +1055,7 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
struct scsi_device *sdev = scmd->device;
struct Scsi_Host *shost = sdev->host;
DECLARE_COMPLETION_ONSTACK(done);
unsigned long timeleft = timeout;
unsigned long timeleft = timeout, delay;
struct scsi_eh_save ses;
const unsigned long stall_for = msecs_to_jiffies(100);
int rtn;
@@ -1066,7 +1066,29 @@ retry:
scsi_log_send(scmd);
scmd->scsi_done = scsi_eh_done;
rtn = shost->hostt->queuecommand(shost, scmd);
/*
* Lock sdev->state_mutex to avoid that scsi_device_quiesce() can
* change the SCSI device state after we have examined it and before
* .queuecommand() is called.
*/
mutex_lock(&sdev->state_mutex);
while (sdev->sdev_state == SDEV_BLOCK && timeleft > 0) {
mutex_unlock(&sdev->state_mutex);
SCSI_LOG_ERROR_RECOVERY(5, sdev_printk(KERN_DEBUG, sdev,
"%s: state %d <> %d\n", __func__, sdev->sdev_state,
SDEV_BLOCK));
delay = min(timeleft, stall_for);
timeleft -= delay;
msleep(jiffies_to_msecs(delay));
mutex_lock(&sdev->state_mutex);
}
if (sdev->sdev_state != SDEV_BLOCK)
rtn = shost->hostt->queuecommand(shost, scmd);
else
rtn = SCSI_MLQUEUE_DEVICE_BUSY;
mutex_unlock(&sdev->state_mutex);
if (rtn) {
if (timeleft > stall_for) {
scsi_eh_restore_cmnd(scmd, &ses);
drivers/scsi/scsi_lib.c
-4
View File
@@ -2616,10 +2616,6 @@ EXPORT_SYMBOL_GPL(scsi_internal_device_block_nowait);
* a legal transition). When the device is in this state, command processing
* is paused until the device leaves the SDEV_BLOCK state. See also
* scsi_internal_device_unblock().
*
* To do: avoid that scsi_send_eh_cmnd() calls queuecommand() after
* scsi_internal_device_block() has blocked a SCSI device and also
* remove the rport mutex lock and unlock calls from srp_queuecommand().
*/
static int scsi_internal_device_block(struct scsi_device *sdev)
{