On 05/05/12 13:04, Bart Van Assche wrote: > Now that we're looking at potential device removal races: since the host > lock push down scsi_dispatch_cmd() is invoked while a reference on the > device is hold but without holding the host lock or the device queue lock. > Shouldn't we make sure that invoking the SCSI device tear down code only > occurs once it is sure that hostt->queuecommand won't be invoked anymore ? (replying to my own e-mail) The patch below makes sure that blk_drain_queue() and blk_cleanup_queue() wait until all queuecommand invocations have finished and hence fixes a race between the SCSI error handler and __scsi_remove_device(). Any feedback is welcome. --- drivers/scsi/scsi_error.c | 14 +++++++++++++- 1 files changed, 13 insertions(+), 1 deletions(-) diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index 386f0c5..947f627 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -781,10 +781,17 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd, struct scsi_device *sdev = scmd->device; struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd); struct Scsi_Host *shost = sdev->host; + struct request_queue *q = sdev->request_queue; DECLARE_COMPLETION_ONSTACK(done); unsigned long timeleft; struct scsi_eh_save ses; - int rtn; + int rtn = FAILED; + + spin_lock_irq(q->queue_lock); + if (blk_queue_dead(q)) + goto out_unlock; + q->rq.count[BLK_RW_SYNC]++; + spin_unlock_irq(q->queue_lock); scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes); shost->eh_action = &done; @@ -838,6 +845,11 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd, if (sdrv && sdrv->eh_action) rtn = sdrv->eh_action(scmd, cmnd, cmnd_size, rtn); + spin_lock_irq(q->queue_lock); + q->rq.count[BLK_RW_SYNC]--; +out_unlock: + spin_unlock_irq(q->queue_lock); + return rtn; } -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
