diff options
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 106 |
1 files changed, 89 insertions, 17 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 98ee55ced592..e5a9526d2037 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -114,6 +114,7 @@ int scsi_queue_insert(struct scsi_cmnd *cmd, int reason) { struct Scsi_Host *host = cmd->device->host; struct scsi_device *device = cmd->device; + struct scsi_target *starget = scsi_target(device); struct request_queue *q = device->request_queue; unsigned long flags; @@ -133,10 +134,17 @@ int scsi_queue_insert(struct scsi_cmnd *cmd, int reason) * if a command is requeued with no other commands outstanding * either for the device or for the host. */ - if (reason == SCSI_MLQUEUE_HOST_BUSY) + switch (reason) { + case SCSI_MLQUEUE_HOST_BUSY: host->host_blocked = host->max_host_blocked; - else if (reason == SCSI_MLQUEUE_DEVICE_BUSY) + break; + case SCSI_MLQUEUE_DEVICE_BUSY: device->device_blocked = device->max_device_blocked; + break; + case SCSI_MLQUEUE_TARGET_BUSY: + starget->target_blocked = starget->max_target_blocked; + break; + } /* * Decrement the counters, since these commands are no longer @@ -460,10 +468,12 @@ static void scsi_init_cmd_errh(struct scsi_cmnd *cmd) void scsi_device_unbusy(struct scsi_device *sdev) { struct Scsi_Host *shost = sdev->host; + struct scsi_target *starget = scsi_target(sdev); unsigned long flags; spin_lock_irqsave(shost->host_lock, flags); shost->host_busy--; + starget->target_busy--; if (unlikely(scsi_host_in_recovery(shost) && (shost->host_failed || shost->host_eh_scheduled))) scsi_eh_wakeup(shost); @@ -519,6 +529,13 @@ static void scsi_single_lun_run(struct scsi_device *current_sdev) spin_unlock_irqrestore(shost->host_lock, flags); } +static inline int scsi_target_is_busy(struct scsi_target *starget) +{ + return ((starget->can_queue > 0 && + starget->target_busy >= starget->can_queue) || + starget->target_blocked); +} + /* * Function: scsi_run_queue() * @@ -533,7 +550,7 @@ static void scsi_single_lun_run(struct scsi_device *current_sdev) */ static void scsi_run_queue(struct request_queue *q) { - struct scsi_device *sdev = q->queuedata; + struct scsi_device *starved_head = NULL, *sdev = q->queuedata; struct Scsi_Host *shost = sdev->host; unsigned long flags; @@ -560,6 +577,21 @@ static void scsi_run_queue(struct request_queue *q) */ sdev = list_entry(shost->starved_list.next, struct scsi_device, starved_entry); + /* + * The *queue_ready functions can add a device back onto the + * starved list's tail, so we must check for a infinite loop. + */ + if (sdev == starved_head) + break; + if (!starved_head) + starved_head = sdev; + + if (scsi_target_is_busy(scsi_target(sdev))) { + list_move_tail(&sdev->starved_entry, + &shost->starved_list); + continue; + } + list_del_init(&sdev->starved_entry); spin_unlock(shost->host_lock); @@ -575,13 +607,6 @@ static void scsi_run_queue(struct request_queue *q) spin_unlock(sdev->request_queue->queue_lock); spin_lock(shost->host_lock); - if (unlikely(!list_empty(&sdev->starved_entry))) - /* - * sdev lost a race, and was put back on the - * starved list. This is unlikely but without this - * in theory we could loop forever. - */ - break; } spin_unlock_irqrestore(shost->host_lock, flags); @@ -681,7 +706,7 @@ static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error, leftover = req->data_len; /* kill remainder if no retrys */ - if (error && blk_noretry_request(req)) + if (error && scsi_noretry_cmd(cmd)) blk_end_request(req, error, leftover); else { if (requeue) { @@ -1344,6 +1369,52 @@ static inline int scsi_dev_queue_ready(struct request_queue *q, return 1; } + +/* + * scsi_target_queue_ready: checks if there we can send commands to target + * @sdev: scsi device on starget to check. + * + * Called with the host lock held. + */ +static inline int scsi_target_queue_ready(struct Scsi_Host *shost, + struct scsi_device *sdev) +{ + struct scsi_target *starget = scsi_target(sdev); + + if (starget->single_lun) { + if (starget->starget_sdev_user && + starget->starget_sdev_user != sdev) + return 0; + starget->starget_sdev_user = sdev; + } + + if (starget->target_busy == 0 && starget->target_blocked) { + /* + * unblock after target_blocked iterates to zero + */ + if (--starget->target_blocked == 0) { + SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget, + "unblocking target at zero depth\n")); + } else { + blk_plug_device(sdev->request_queue); + return 0; + } + } + + if (scsi_target_is_busy(starget)) { + if (list_empty(&sdev->starved_entry)) { + list_add_tail(&sdev->starved_entry, + &shost->starved_list); + return 0; + } + } + + /* We're OK to process the command, so we can't be starved */ + if (!list_empty(&sdev->starved_entry)) + list_del_init(&sdev->starved_entry); + return 1; +} + /* * scsi_host_queue_ready: if we can send requests to shost, return 1 else * return 0. We must end up running the queue again whenever 0 is @@ -1390,6 +1461,7 @@ static void scsi_kill_request(struct request *req, struct request_queue *q) { struct scsi_cmnd *cmd = req->special; struct scsi_device *sdev = cmd->device; + struct scsi_target *starget = scsi_target(sdev); struct Scsi_Host *shost = sdev->host; blkdev_dequeue_request(req); @@ -1413,6 +1485,7 @@ static void scsi_kill_request(struct request *req, struct request_queue *q) spin_unlock(sdev->request_queue->queue_lock); spin_lock(shost->host_lock); shost->host_busy++; + starget->target_busy++; spin_unlock(shost->host_lock); spin_lock(sdev->request_queue->queue_lock); @@ -1550,14 +1623,13 @@ static void scsi_request_fn(struct request_queue *q) goto not_ready; } + if (!scsi_target_queue_ready(shost, sdev)) + goto not_ready; + if (!scsi_host_queue_ready(q, shost, sdev)) goto not_ready; - if (scsi_target(sdev)->single_lun) { - if (scsi_target(sdev)->starget_sdev_user && - scsi_target(sdev)->starget_sdev_user != sdev) - goto not_ready; - scsi_target(sdev)->starget_sdev_user = sdev; - } + + scsi_target(sdev)->target_busy++; shost->host_busy++; /* |