Avoid taking the host-wide host_lock to check the per-host queue limit. Instead we do an atomic_inc_return early on to grab our slot in the queue, and if nessecary decrement it after finishing all checks. Signed-off-by: Christoph Hellwig --- drivers/scsi/advansys.c | 4 +- drivers/scsi/libiscsi.c | 4 +- drivers/scsi/libsas/sas_scsi_host.c | 5 ++- drivers/scsi/qlogicpti.c | 2 +- drivers/scsi/scsi.c | 2 +- drivers/scsi/scsi_error.c | 6 +-- drivers/scsi/scsi_lib.c | 71 +++++++++++++++++++++-------------- drivers/scsi/scsi_sysfs.c | 9 ++++- include/scsi/scsi_host.h | 10 ++--- 9 files changed, 65 insertions(+), 48 deletions(-) diff --git a/drivers/scsi/advansys.c b/drivers/scsi/advansys.c index d814588..0a6ecbd 100644 --- a/drivers/scsi/advansys.c +++ b/drivers/scsi/advansys.c @@ -2512,7 +2512,7 @@ static void asc_prt_scsi_host(struct Scsi_Host *s) printk("Scsi_Host at addr 0x%p, device %s\n", s, dev_name(boardp->dev)); printk(" host_busy %u, host_no %d,\n", - s->host_busy, s->host_no); + atomic_read(&s->host_busy), s->host_no); printk(" base 0x%lx, io_port 0x%lx, irq %d,\n", (ulong)s->base, (ulong)s->io_port, boardp->irq); @@ -3346,7 +3346,7 @@ static void asc_prt_driver_conf(struct seq_file *m, struct Scsi_Host *shost) seq_printf(m, " host_busy %u, max_id %u, max_lun %u, max_channel %u\n", - shost->host_busy, shost->max_id, + atomic_read(&shost->host_busy), shost->max_id, shost->max_lun, shost->max_channel); seq_printf(m, diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c index 4046241..718ca88 100644 --- a/drivers/scsi/libiscsi.c +++ b/drivers/scsi/libiscsi.c @@ -2922,7 +2922,7 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn) */ for (;;) { spin_lock_irqsave(session->host->host_lock, flags); - if (!session->host->host_busy) { /* OK for ERL == 0 */ + if (!atomic_read(&session->host->host_busy)) { /* OK for ERL == 0 */ spin_unlock_irqrestore(session->host->host_lock, flags); break; } @@ -2930,7 +2930,7 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn) msleep_interruptible(500); iscsi_conn_printk(KERN_INFO, conn, "iscsi conn_destroy(): " "host_busy %d host_failed %d\n", - session->host->host_busy, + atomic_read(&session->host->host_busy), session->host->host_failed); /* * force eh_abort() to unblock diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c index da3aee1..9423009 100644 --- a/drivers/scsi/libsas/sas_scsi_host.c +++ b/drivers/scsi/libsas/sas_scsi_host.c @@ -812,7 +812,7 @@ retry: spin_unlock_irq(shost->host_lock); SAS_DPRINTK("Enter %s busy: %d failed: %d\n", - __func__, shost->host_busy, shost->host_failed); + __func__, atomic_read(&shost->host_busy), shost->host_failed); /* * Deal with commands that still have SAS tasks (i.e. they didn't * complete via the normal sas_task completion mechanism), @@ -857,7 +857,8 @@ out: goto retry; SAS_DPRINTK("--- Exit %s: busy: %d failed: %d tries: %d\n", - __func__, shost->host_busy, shost->host_failed, tries); + __func__, atomic_read(&shost->host_busy), + shost->host_failed, tries); } enum blk_eh_timer_return sas_scsi_timed_out(struct scsi_cmnd *cmd) diff --git a/drivers/scsi/qlogicpti.c b/drivers/scsi/qlogicpti.c index 6d48d30..740ae49 100644 --- a/drivers/scsi/qlogicpti.c +++ b/drivers/scsi/qlogicpti.c @@ -959,7 +959,7 @@ static inline void update_can_queue(struct Scsi_Host *host, u_int in_ptr, u_int /* Temporary workaround until bug is found and fixed (one bug has been found already, but fixing it makes things even worse) -jj */ int num_free = QLOGICPTI_REQ_QUEUE_LEN - REQ_QUEUE_DEPTH(in_ptr, out_ptr) - 64; - host->can_queue = host->host_busy + num_free; + host->can_queue = atomic_read(&host->host_busy) + num_free; host->sg_tablesize = QLOGICPTI_MAX_SG(num_free); } diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index eff189f..a0b5e6f 100644 --- a/drivers/scsi/scsi.c +++ b/drivers/scsi/scsi.c @@ -596,7 +596,7 @@ void scsi_log_completion(struct scsi_cmnd *cmd, int disposition) if (level > 3) scmd_printk(KERN_INFO, cmd, "scsi host busy %d failed %d\n", - cmd->device->host->host_busy, + atomic_read(&cmd->device->host->host_busy), cmd->device->host->host_failed); } } diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index 771c16b..759c168 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -59,7 +59,7 @@ static int scsi_try_to_abort_cmd(struct scsi_host_template *, /* called with shost->host_lock held */ void scsi_eh_wakeup(struct Scsi_Host *shost) { - if (shost->host_busy == shost->host_failed) { + if (atomic_read(&shost->host_busy) == shost->host_failed) { trace_scsi_eh_wakeup(shost); wake_up_process(shost->ehandler); SCSI_LOG_ERROR_RECOVERY(5, @@ -2141,7 +2141,7 @@ int scsi_error_handler(void *data) while (!kthread_should_stop()) { set_current_state(TASK_INTERRUPTIBLE); if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) || - shost->host_failed != shost->host_busy) { + shost->host_failed != atomic_read(&shost->host_busy)) { SCSI_LOG_ERROR_RECOVERY(1, printk("scsi_eh_%d: sleeping\n", shost->host_no)); @@ -2153,7 +2153,7 @@ int scsi_error_handler(void *data) SCSI_LOG_ERROR_RECOVERY(1, printk("scsi_eh_%d: waking up %d/%d/%d\n", shost->host_no, shost->host_eh_scheduled, - shost->host_failed, shost->host_busy)); + shost->host_failed, atomic_read(&shost->host_busy))); /* * We have a host that is failing for some reason. Figure out diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 01a631e..f1ce764 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -281,14 +281,17 @@ void scsi_device_unbusy(struct scsi_device *sdev) struct scsi_target *starget = scsi_target(sdev); unsigned long flags; - spin_lock_irqsave(shost->host_lock, flags); - shost->host_busy--; + atomic_dec(&shost->host_busy); atomic_dec(&starget->target_busy); + if (unlikely(scsi_host_in_recovery(shost) && - (shost->host_failed || shost->host_eh_scheduled))) + (shost->host_failed || shost->host_eh_scheduled))) { + spin_lock_irqsave(shost->host_lock, flags); scsi_eh_wakeup(shost); - spin_unlock(shost->host_lock); - spin_lock(sdev->request_queue->queue_lock); + spin_unlock_irqrestore(shost->host_lock, flags); + } + + spin_lock_irqsave(sdev->request_queue->queue_lock, flags); sdev->device_busy--; spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags); } @@ -356,7 +359,8 @@ static inline int scsi_target_is_busy(struct scsi_target *starget) static inline int scsi_host_is_busy(struct Scsi_Host *shost) { - if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) || + if ((shost->can_queue > 0 && + atomic_read(&shost->host_busy) >= shost->can_queue) || shost->host_blocked || shost->host_self_blocked) return 1; @@ -1332,38 +1336,51 @@ static inline int scsi_host_queue_ready(struct request_queue *q, struct Scsi_Host *shost, struct scsi_device *sdev) { - int ret = 0; - - spin_lock_irq(shost->host_lock); + unsigned int busy; if (scsi_host_in_recovery(shost)) - goto out; - if (shost->host_busy == 0 && shost->host_blocked) { + return 0; + + busy = atomic_inc_return(&shost->host_busy) - 1; + if (busy == 0 && shost->host_blocked) { /* * unblock after host_blocked iterates to zero */ - if (--shost->host_blocked != 0) - goto out; + spin_lock_irq(shost->host_lock); + if (--shost->host_blocked != 0) { + spin_unlock_irq(shost->host_lock); + goto out_dec; + } + spin_unlock_irq(shost->host_lock); SCSI_LOG_MLQUEUE(3, printk("scsi%d unblocking host at zero depth\n", shost->host_no)); } - if (scsi_host_is_busy(shost)) { - if (list_empty(&sdev->starved_entry)) - list_add_tail(&sdev->starved_entry, &shost->starved_list); - goto out; - } + + if (shost->can_queue > 0 && busy >= shost->can_queue) + goto starved; + if (shost->host_blocked || shost->host_self_blocked) + goto starved; /* 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); + if (!list_empty(&sdev->starved_entry)) { + spin_lock_irq(shost->host_lock); + if (!list_empty(&sdev->starved_entry)) + list_del_init(&sdev->starved_entry); + spin_unlock_irq(shost->host_lock); + } + + return 1; - shost->host_busy++; - ret = 1; -out: +starved: + spin_lock_irq(shost->host_lock); + if (list_empty(&sdev->starved_entry)) + list_add_tail(&sdev->starved_entry, &shost->starved_list); spin_unlock_irq(shost->host_lock); - return ret; +out_dec: + atomic_dec(&shost->host_busy); + return 0; } /* @@ -1427,12 +1444,8 @@ static void scsi_kill_request(struct request *req, struct request_queue *q) * with the locks as normal issue path does. */ sdev->device_busy++; - spin_unlock(sdev->request_queue->queue_lock); - spin_lock(shost->host_lock); - shost->host_busy++; + atomic_inc(&shost->host_busy); atomic_inc(&starget->target_busy); - spin_unlock(shost->host_lock); - spin_lock(sdev->request_queue->queue_lock); blk_complete_request(req); } diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index 9117d0b..658ee82 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -332,7 +332,6 @@ store_shost_eh_deadline(struct device *dev, struct device_attribute *attr, static DEVICE_ATTR(eh_deadline, S_IRUGO | S_IWUSR, show_shost_eh_deadline, store_shost_eh_deadline); shost_rd_attr(unique_id, "%u\n"); -shost_rd_attr(host_busy, "%hu\n"); shost_rd_attr(cmd_per_lun, "%hd\n"); shost_rd_attr(can_queue, "%hd\n"); shost_rd_attr(sg_tablesize, "%hu\n"); @@ -342,6 +341,14 @@ shost_rd_attr(prot_capabilities, "%u\n"); shost_rd_attr(prot_guard_type, "%hd\n"); shost_rd_attr2(proc_name, hostt->proc_name, "%s\n"); +static ssize_t +show_host_busy(struct device *dev, struct device_attribute *attr, char *buf) +{ + struct Scsi_Host *shost = class_to_shost(dev); + return snprintf(buf, 20, "%hu\n", atomic_read(&shost->host_busy)); +} +static DEVICE_ATTR(host_busy, S_IRUGO, show_host_busy, NULL); + static struct attribute *scsi_sysfs_shost_attrs[] = { &dev_attr_unique_id.attr, &dev_attr_host_busy.attr, diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index 94844fc..590e1af 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -603,13 +603,9 @@ struct Scsi_Host { */ struct blk_queue_tag *bqt; - /* - * The following two fields are protected with host_lock; - * however, eh routines can safely access during eh processing - * without acquiring the lock. - */ - unsigned int host_busy; /* commands actually active on low-level */ - unsigned int host_failed; /* commands that failed. */ + atomic_t host_busy; /* commands actually active on low-level */ + unsigned int host_failed; /* commands that failed. + protected by host_lock */ unsigned int host_eh_scheduled; /* EH scheduled without command */ unsigned int host_no; /* Used for IOCTL_GET_IDLUN, /proc/scsi et al. */ -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/