From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Bart Van Assche To: Jens Axboe Cc: linux-block@vger.kernel.org, "Martin K . Petersen" , Christoph Hellwig , Hannes Reinecke , Jason Gunthorpe , Doug Ledford , linux-scsi@vger.kernel.org, linux-rdma@vger.kernel.org, Bart Van Assche , Johannes Thumshirn , Ming Lei Subject: [PATCH v2 3/4] scsi: Avoid that .queuecommand() gets called for a quiesced SCSI device Date: Wed, 10 Jan 2018 10:18:16 -0800 Message-Id: <20180110181817.25166-4-bart.vanassche@wdc.com> In-Reply-To: <20180110181817.25166-1-bart.vanassche@wdc.com> References: <20180110181817.25166-1-bart.vanassche@wdc.com> List-ID: 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 Reviewed-by: Hannes Reinecke Cc: Martin K. Petersen Cc: Christoph Hellwig Cc: Johannes Thumshirn Cc: Ming Lei --- 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