X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=drivers%2Fscsi%2Fscsi_lib.c;h=f5d3b96890dc6d9dd180eb86bb0f2b737a60e7f1;hb=6c5121b78ba5c70a9990e2af6cb4d6bbffe0d4d8;hp=98ee55ced5922c4ff14634bd320725eb2d3b5db0;hpb=13dd7f876dffb44088c5435c3df1986e33cff960;p=linux-2.6-omap-h63xx.git diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 98ee55ced59..f5d3b96890d 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 +529,30 @@ static void scsi_single_lun_run(struct scsi_device *current_sdev) spin_unlock_irqrestore(shost->host_lock, flags); } +static inline int scsi_device_is_busy(struct scsi_device *sdev) +{ + if (sdev->device_busy >= sdev->queue_depth || sdev->device_blocked) + return 1; + + return 0; +} + +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); +} + +static inline int scsi_host_is_busy(struct Scsi_Host *shost) +{ + if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) || + shost->host_blocked || shost->host_self_blocked) + return 1; + + return 0; +} + /* * Function: scsi_run_queue() * @@ -533,7 +567,7 @@ 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; @@ -541,11 +575,7 @@ static void scsi_run_queue(struct request_queue *q) scsi_single_lun_run(sdev); spin_lock_irqsave(shost->host_lock, flags); - while (!list_empty(&shost->starved_list) && - !shost->host_blocked && !shost->host_self_blocked && - !((shost->can_queue > 0) && - (shost->host_busy >= shost->can_queue))) { - + while (!list_empty(&shost->starved_list) && !scsi_host_is_busy(shost)) { int flagset; /* @@ -560,6 +590,21 @@ 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 +620,6 @@ 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 +719,7 @@ 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) { @@ -1323,8 +1361,6 @@ int scsi_prep_fn(struct request_queue *q, struct request *req) static inline int scsi_dev_queue_ready(struct request_queue *q, struct scsi_device *sdev) { - if (sdev->device_busy >= sdev->queue_depth) - return 0; if (sdev->device_busy == 0 && sdev->device_blocked) { /* * unblock after device_blocked iterates to zero @@ -1338,12 +1374,58 @@ static inline int scsi_dev_queue_ready(struct request_queue *q, return 0; } } - if (sdev->device_blocked) + if (scsi_device_is_busy(sdev)) return 0; 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 @@ -1369,8 +1451,7 @@ static inline int scsi_host_queue_ready(struct request_queue *q, return 0; } } - if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) || - shost->host_blocked || shost->host_self_blocked) { + if (scsi_host_is_busy(shost)) { if (list_empty(&sdev->starved_entry)) list_add_tail(&sdev->starved_entry, &shost->starved_list); return 0; @@ -1383,6 +1464,37 @@ static inline int scsi_host_queue_ready(struct request_queue *q, return 1; } +/* + * 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 */ @@ -1390,6 +1502,7 @@ 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 +1526,7 @@ 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 +1664,13 @@ 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++; /* @@ -1685,6 +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; } @@ -2033,22 +2147,21 @@ scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries, do { result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr, timeout, retries); - } while ((driver_byte(result) & DRIVER_SENSE) && - sshdr && sshdr->sense_key == UNIT_ATTENTION && - --retries); + if (sdev->removable && scsi_sense_valid(sshdr) && + sshdr->sense_key == UNIT_ATTENTION) + sdev->changed = 1; + } while (scsi_sense_valid(sshdr) && + sshdr->sense_key == UNIT_ATTENTION && --retries); if (!sshdr) /* could not allocate sense buffer, so can't process it */ return result; - if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) { - - if ((scsi_sense_valid(sshdr)) && - ((sshdr->sense_key == UNIT_ATTENTION) || - (sshdr->sense_key == NOT_READY))) { - sdev->changed = 1; - result = 0; - } + if (sdev->removable && scsi_sense_valid(sshdr) && + (sshdr->sense_key == UNIT_ATTENTION || + sshdr->sense_key == NOT_READY)) { + sdev->changed = 1; + result = 0; } if (!sshdr_external) kfree(sshdr);