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
blk_start_wait_if_quiesced() / blk_finish_wait_if_quiesced().
Note: converting the .queuecommand() call in scsi_send_eh_cmnd() into
code that calls blk_get_request(), e.g. scsi_execute_req(), is not an
option since scsi_send_eh_cmnd() can be called if all requests are
allocated and if no requests will make progress without aborting any
of these requests.
Signed-off-by: Bart Van Assche <bart.vanass...@wdc.com>
Reviewed-by: Hannes Reinecke <h...@suse.de>
Cc: Martin K. Petersen <martin.peter...@oracle.com>
Cc: Christoph Hellwig <h...@lst.de>
Cc: Johannes Thumshirn <jthumsh...@suse.de>
Cc: Ming Lei <ming....@redhat.com>
---
drivers/scsi/scsi_error.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 62b56de38ae8..f7154ea86715 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -1016,6 +1016,7 @@ 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;
+ struct request_queue *q = sdev->request_queue;
DECLARE_COMPLETION_ONSTACK(done);
unsigned long timeleft = timeout;
struct scsi_eh_save ses;
@@ -1028,7 +1029,9 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd,
unsigned char *cmnd,
scsi_log_send(scmd);
scmd->scsi_done = scsi_eh_done;
+ blk_start_wait_if_quiesced(q);
rtn = shost->hostt->queuecommand(shost, scmd);
+ blk_finish_wait_if_quiesced(q);
if (rtn) {
if (timeleft > stall_for) {
scsi_eh_restore_cmnd(scmd, &ses);
--
2.15.1
