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authorTejun Heo <tj@kernel.org>2010-07-02 04:03:52 -0400
committerTejun Heo <tj@kernel.org>2010-07-02 04:59:24 -0400
commitad72cf9885c536e3adae03f8337557ac9dd1e4bb (patch)
treee93af7f241987ffe365792c0130d182b0ac890d1 /drivers/ata
parentd313dd85ad846bc768d58e9ceb28588f917f4c9a (diff)
libata: take advantage of cmwq and remove concurrency limitations
libata has two concurrency related limitations. a. ata_wq which is used for polling PIO has single thread per CPU. If there are multiple devices doing polling PIO on the same CPU, they can't be executed simultaneously. b. ata_aux_wq which is used for SCSI probing has single thread. In cases where SCSI probing is stalled for extended period of time which is possible for ATAPI devices, this will stall all probing. #a is solved by increasing maximum concurrency of ata_wq. Please note that polling PIO might be used under allocation path and thus needs to be served by a separate wq with a rescuer. #b is solved by using the default wq instead and achieving exclusion via per-port mutex. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Jeff Garzik <jgarzik@pobox.com>
Diffstat (limited to 'drivers/ata')
-rw-r--r--drivers/ata/libata-core.c20
-rw-r--r--drivers/ata/libata-eh.c4
-rw-r--r--drivers/ata/libata-scsi.c10
-rw-r--r--drivers/ata/libata-sff.c9
-rw-r--r--drivers/ata/libata.h1
5 files changed, 14 insertions, 30 deletions
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index ddf8e486278..4f78741692d 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -98,8 +98,6 @@ static unsigned long ata_dev_blacklisted(const struct ata_device *dev);
98 98
99unsigned int ata_print_id = 1; 99unsigned int ata_print_id = 1;
100 100
101struct workqueue_struct *ata_aux_wq;
102
103struct ata_force_param { 101struct ata_force_param {
104 const char *name; 102 const char *name;
105 unsigned int cbl; 103 unsigned int cbl;
@@ -5611,6 +5609,7 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
5611 ap->msg_enable = ATA_MSG_DRV | ATA_MSG_ERR | ATA_MSG_WARN; 5609 ap->msg_enable = ATA_MSG_DRV | ATA_MSG_ERR | ATA_MSG_WARN;
5612#endif 5610#endif
5613 5611
5612 mutex_init(&ap->scsi_scan_mutex);
5614 INIT_DELAYED_WORK(&ap->hotplug_task, ata_scsi_hotplug); 5613 INIT_DELAYED_WORK(&ap->hotplug_task, ata_scsi_hotplug);
5615 INIT_WORK(&ap->scsi_rescan_task, ata_scsi_dev_rescan); 5614 INIT_WORK(&ap->scsi_rescan_task, ata_scsi_dev_rescan);
5616 INIT_LIST_HEAD(&ap->eh_done_q); 5615 INIT_LIST_HEAD(&ap->eh_done_q);
@@ -6549,29 +6548,20 @@ static int __init ata_init(void)
6549 6548
6550 ata_parse_force_param(); 6549 ata_parse_force_param();
6551 6550
6552 ata_aux_wq = create_singlethread_workqueue("ata_aux");
6553 if (!ata_aux_wq)
6554 goto fail;
6555
6556 rc = ata_sff_init(); 6551 rc = ata_sff_init();
6557 if (rc) 6552 if (rc) {
6558 goto fail; 6553 kfree(ata_force_tbl);
6554 return rc;
6555 }
6559 6556
6560 printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n"); 6557 printk(KERN_DEBUG "libata version " DRV_VERSION " loaded.\n");
6561 return 0; 6558 return 0;
6562
6563fail:
6564 kfree(ata_force_tbl);
6565 if (ata_aux_wq)
6566 destroy_workqueue(ata_aux_wq);
6567 return rc;
6568} 6559}
6569 6560
6570static void __exit ata_exit(void) 6561static void __exit ata_exit(void)
6571{ 6562{
6572 ata_sff_exit(); 6563 ata_sff_exit();
6573 kfree(ata_force_tbl); 6564 kfree(ata_force_tbl);
6574 destroy_workqueue(ata_aux_wq);
6575} 6565}
6576 6566
6577subsys_initcall(ata_init); 6567subsys_initcall(ata_init);
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index f77a67303f8..4d2af824dd2 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -727,7 +727,7 @@ void ata_scsi_error(struct Scsi_Host *host)
727 if (ap->pflags & ATA_PFLAG_LOADING) 727 if (ap->pflags & ATA_PFLAG_LOADING)
728 ap->pflags &= ~ATA_PFLAG_LOADING; 728 ap->pflags &= ~ATA_PFLAG_LOADING;
729 else if (ap->pflags & ATA_PFLAG_SCSI_HOTPLUG) 729 else if (ap->pflags & ATA_PFLAG_SCSI_HOTPLUG)
730 queue_delayed_work(ata_aux_wq, &ap->hotplug_task, 0); 730 schedule_delayed_work(&ap->hotplug_task, 0);
731 731
732 if (ap->pflags & ATA_PFLAG_RECOVERED) 732 if (ap->pflags & ATA_PFLAG_RECOVERED)
733 ata_port_printk(ap, KERN_INFO, "EH complete\n"); 733 ata_port_printk(ap, KERN_INFO, "EH complete\n");
@@ -2944,7 +2944,7 @@ static int ata_eh_revalidate_and_attach(struct ata_link *link,
2944 ehc->i.flags |= ATA_EHI_SETMODE; 2944 ehc->i.flags |= ATA_EHI_SETMODE;
2945 2945
2946 /* schedule the scsi_rescan_device() here */ 2946 /* schedule the scsi_rescan_device() here */
2947 queue_work(ata_aux_wq, &(ap->scsi_rescan_task)); 2947 schedule_work(&(ap->scsi_rescan_task));
2948 } else if (dev->class == ATA_DEV_UNKNOWN && 2948 } else if (dev->class == ATA_DEV_UNKNOWN &&
2949 ehc->tries[dev->devno] && 2949 ehc->tries[dev->devno] &&
2950 ata_class_enabled(ehc->classes[dev->devno])) { 2950 ata_class_enabled(ehc->classes[dev->devno])) {
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index a54273d2c3c..d75c9c479d1 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3435,7 +3435,7 @@ void ata_scsi_scan_host(struct ata_port *ap, int sync)
3435 " switching to async\n"); 3435 " switching to async\n");
3436 } 3436 }
3437 3437
3438 queue_delayed_work(ata_aux_wq, &ap->hotplug_task, 3438 queue_delayed_work(system_long_wq, &ap->hotplug_task,
3439 round_jiffies_relative(HZ)); 3439 round_jiffies_relative(HZ));
3440} 3440}
3441 3441
@@ -3582,6 +3582,7 @@ void ata_scsi_hotplug(struct work_struct *work)
3582 } 3582 }
3583 3583
3584 DPRINTK("ENTER\n"); 3584 DPRINTK("ENTER\n");
3585 mutex_lock(&ap->scsi_scan_mutex);
3585 3586
3586 /* Unplug detached devices. We cannot use link iterator here 3587 /* Unplug detached devices. We cannot use link iterator here
3587 * because PMP links have to be scanned even if PMP is 3588 * because PMP links have to be scanned even if PMP is
@@ -3595,6 +3596,7 @@ void ata_scsi_hotplug(struct work_struct *work)
3595 /* scan for new ones */ 3596 /* scan for new ones */
3596 ata_scsi_scan_host(ap, 0); 3597 ata_scsi_scan_host(ap, 0);
3597 3598
3599 mutex_unlock(&ap->scsi_scan_mutex);
3598 DPRINTK("EXIT\n"); 3600 DPRINTK("EXIT\n");
3599} 3601}
3600 3602
@@ -3673,9 +3675,7 @@ static int ata_scsi_user_scan(struct Scsi_Host *shost, unsigned int channel,
3673 * @work: Pointer to ATA port to perform scsi_rescan_device() 3675 * @work: Pointer to ATA port to perform scsi_rescan_device()
3674 * 3676 *
3675 * After ATA pass thru (SAT) commands are executed successfully, 3677 * After ATA pass thru (SAT) commands are executed successfully,
3676 * libata need to propagate the changes to SCSI layer. This 3678 * libata need to propagate the changes to SCSI layer.
3677 * function must be executed from ata_aux_wq such that sdev
3678 * attach/detach don't race with rescan.
3679 * 3679 *
3680 * LOCKING: 3680 * LOCKING:
3681 * Kernel thread context (may sleep). 3681 * Kernel thread context (may sleep).
@@ -3688,6 +3688,7 @@ void ata_scsi_dev_rescan(struct work_struct *work)
3688 struct ata_device *dev; 3688 struct ata_device *dev;
3689 unsigned long flags; 3689 unsigned long flags;
3690 3690
3691 mutex_lock(&ap->scsi_scan_mutex);
3691 spin_lock_irqsave(ap->lock, flags); 3692 spin_lock_irqsave(ap->lock, flags);
3692 3693
3693 ata_for_each_link(link, ap, EDGE) { 3694 ata_for_each_link(link, ap, EDGE) {
@@ -3707,6 +3708,7 @@ void ata_scsi_dev_rescan(struct work_struct *work)
3707 } 3708 }
3708 3709
3709 spin_unlock_irqrestore(ap->lock, flags); 3710 spin_unlock_irqrestore(ap->lock, flags);
3711 mutex_unlock(&ap->scsi_scan_mutex);
3710} 3712}
3711 3713
3712/** 3714/**
diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index efa4a18cfb9..674c1436491 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -3318,14 +3318,7 @@ void ata_sff_port_init(struct ata_port *ap)
3318 3318
3319int __init ata_sff_init(void) 3319int __init ata_sff_init(void)
3320{ 3320{
3321 /* 3321 ata_sff_wq = alloc_workqueue("ata_sff", WQ_RESCUER, WQ_MAX_ACTIVE);
3322 * FIXME: In UP case, there is only one workqueue thread and if you
3323 * have more than one PIO device, latency is bloody awful, with
3324 * occasional multi-second "hiccups" as one PIO device waits for
3325 * another. It's an ugly wart that users DO occasionally complain
3326 * about; luckily most users have at most one PIO polled device.
3327 */
3328 ata_sff_wq = create_workqueue("ata_sff");
3329 if (!ata_sff_wq) 3322 if (!ata_sff_wq)
3330 return -ENOMEM; 3323 return -ENOMEM;
3331 3324
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 4b84ed60324..9ce1ecc63e3 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -54,7 +54,6 @@ enum {
54}; 54};
55 55
56extern unsigned int ata_print_id; 56extern unsigned int ata_print_id;
57extern struct workqueue_struct *ata_aux_wq;
58extern int atapi_passthru16; 57extern int atapi_passthru16;
59extern int libata_fua; 58extern int libata_fua;
60extern int libata_noacpi; 59extern int libata_noacpi;