diff options
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 1e7c9e9ef77..f5d3b96890d 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1465,6 +1465,37 @@ static inline int scsi_host_queue_ready(struct request_queue *q, } /* + * Busy state exporting function for request stacking drivers. + * + * For efficiency, no lock is taken to check the busy state of + * shost/starget/sdev, since the returned value is not guaranteed and + * may be changed after request stacking drivers call the function, + * regardless of taking lock or not. + * + * When scsi can't dispatch I/Os anymore and needs to kill I/Os + * (e.g. !sdev), scsi needs to return 'not busy'. + * Otherwise, request stacking drivers may hold requests forever. + */ +static int scsi_lld_busy(struct request_queue *q) +{ + struct scsi_device *sdev = q->queuedata; + struct Scsi_Host *shost; + struct scsi_target *starget; + + if (!sdev) + return 0; + + shost = sdev->host; + starget = scsi_target(sdev); + + if (scsi_host_in_recovery(shost) || scsi_host_is_busy(shost) || + scsi_target_is_busy(starget) || scsi_device_is_busy(sdev)) + return 1; + + return 0; +} + +/* * Kill a request for a dead device */ static void scsi_kill_request(struct request *req, struct request_queue *q) @@ -1767,6 +1798,7 @@ struct request_queue *scsi_alloc_queue(struct scsi_device *sdev) blk_queue_prep_rq(q, scsi_prep_fn); blk_queue_softirq_done(q, scsi_softirq_done); blk_queue_rq_timed_out(q, scsi_times_out); + blk_queue_lld_busy(q, scsi_lld_busy); return q; } |