Commit bbe9fb0d authored by Bart Van Assche's avatar Bart Van Assche Committed by Martin K. Petersen
Browse files

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



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 <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent ac88c1f6

drivers/scsi/scsi_error.c

+24 −2
Original line number Diff line number Diff line
@@ -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;



	/*

	 * 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

+0 −4
Original line number Diff line number Diff line
@@ -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)

{

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