From b1124cd3ec97406c767b90bf7e93ecd2d2915592 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 19 Dec 2011 16:42:34 -0800 Subject: [PATCH] [SCSI] libsas: introduce sas_drain_work() When an lldd invokes ->notify_port_event() it can trigger a chain of libsas events to: 1/ form the port and find the direct attached device 2/ if the attached device is an expander perform domain discovery A call to flush_workqueue() will only flush the initial port formation work. Currently libsas users need to call scsi_flush_work() up to the max depth of chain (which will grow from 2 to 3 when ata discovery is moved to its own discovery event). Instead of open coding multiple calls switch to use drain_workqueue() to flush sas work. drain_workqueue() does not handle new work submitted during the drain so libsas needs a bit of infrastructure to hold off unchained work submissions while a drain is in flight. A lldd ->notify() event is considered 'unchained' while a sas_discover_event() is 'chained'. As Tejun notes: "For now, I think it would be best to add private wrapper in libsas to support deferring unchained work items while draining." Signed-off-by: Dan Williams Signed-off-by: James Bottomley --- drivers/scsi/aic94xx/aic94xx_init.c | 2 +- drivers/scsi/isci/host.c | 8 ++--- drivers/scsi/libsas/sas_discover.c | 21 ++++++++++- drivers/scsi/libsas/sas_event.c | 55 +++++++++++++++++++++++++++++ drivers/scsi/libsas/sas_init.c | 9 +++-- drivers/scsi/libsas/sas_internal.h | 14 -------- drivers/scsi/mvsas/mv_sas.c | 2 +- drivers/scsi/pm8001/pm8001_sas.c | 4 ++- include/scsi/libsas.h | 4 +++ 9 files changed, 93 insertions(+), 26 deletions(-) diff --git a/drivers/scsi/aic94xx/aic94xx_init.c b/drivers/scsi/aic94xx/aic94xx_init.c index 8db4e727628a..2b3717f6d22c 100644 --- a/drivers/scsi/aic94xx/aic94xx_init.c +++ b/drivers/scsi/aic94xx/aic94xx_init.c @@ -971,7 +971,7 @@ static int asd_scan_finished(struct Scsi_Host *shost, unsigned long time) if (time < HZ) return 0; /* Wait for discovery to finish */ - scsi_flush_work(shost); + sas_drain_work(SHOST_TO_SAS_HA(shost)); return 1; } diff --git a/drivers/scsi/isci/host.c b/drivers/scsi/isci/host.c index 508aa8ce25b4..e3cf3832c5b6 100644 --- a/drivers/scsi/isci/host.c +++ b/drivers/scsi/isci/host.c @@ -650,15 +650,13 @@ static void isci_host_start_complete(struct isci_host *ihost, enum sci_status co int isci_host_scan_finished(struct Scsi_Host *shost, unsigned long time) { - struct isci_host *ihost = SHOST_TO_SAS_HA(shost)->lldd_ha; + struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost); + struct isci_host *ihost = ha->lldd_ha; if (test_bit(IHOST_START_PENDING, &ihost->flags)) return 0; - /* todo: use sas_flush_discovery once it is upstream */ - scsi_flush_work(shost); - - scsi_flush_work(shost); + sas_drain_work(ha); dev_dbg(&ihost->pdev->dev, "%s: ihost->status = %d, time = %ld\n", diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c index ed041189e764..32e011766046 100644 --- a/drivers/scsi/libsas/sas_discover.c +++ b/drivers/scsi/libsas/sas_discover.c @@ -367,6 +367,25 @@ static void sas_revalidate_domain(struct work_struct *work) /* ---------- Events ---------- */ +static void sas_chain_work(struct sas_ha_struct *ha, struct work_struct *work) +{ + /* chained work is not subject to SA_HA_DRAINING or SAS_HA_REGISTERED */ + scsi_queue_work(ha->core.shost, work); +} + +static void sas_chain_event(int event, unsigned long *pending, + struct work_struct *work, + struct sas_ha_struct *ha) +{ + if (!test_and_set_bit(event, pending)) { + unsigned long flags; + + spin_lock_irqsave(&ha->state_lock, flags); + sas_chain_work(ha, work); + spin_unlock_irqrestore(&ha->state_lock, flags); + } +} + int sas_discover_event(struct asd_sas_port *port, enum discover_event ev) { struct sas_discovery *disc; @@ -377,7 +396,7 @@ int sas_discover_event(struct asd_sas_port *port, enum discover_event ev) BUG_ON(ev >= DISC_NUM_EVENTS); - sas_queue_event(ev, &disc->pending, &disc->disc_work[ev].work, port->ha); + sas_chain_event(ev, &disc->pending, &disc->disc_work[ev].work, port->ha); return 0; } diff --git a/drivers/scsi/libsas/sas_event.c b/drivers/scsi/libsas/sas_event.c index 9c084bc09bbd..e5035aa4c2a6 100644 --- a/drivers/scsi/libsas/sas_event.c +++ b/drivers/scsi/libsas/sas_event.c @@ -22,10 +22,65 @@ * */ +#include #include #include "sas_internal.h" #include "sas_dump.h" +static void sas_queue_work(struct sas_ha_struct *ha, struct work_struct *work) +{ + if (!test_bit(SAS_HA_REGISTERED, &ha->state)) + return; + + if (test_bit(SAS_HA_DRAINING, &ha->state)) + list_add(&work->entry, &ha->defer_q); + else + scsi_queue_work(ha->core.shost, work); +} + +static void sas_queue_event(int event, unsigned long *pending, + struct work_struct *work, + struct sas_ha_struct *ha) +{ + if (!test_and_set_bit(event, pending)) { + unsigned long flags; + + spin_lock_irqsave(&ha->state_lock, flags); + sas_queue_work(ha, work); + spin_unlock_irqrestore(&ha->state_lock, flags); + } +} + +int sas_drain_work(struct sas_ha_struct *ha) +{ + struct workqueue_struct *wq = ha->core.shost->work_q; + struct work_struct *w, *_w; + int err; + + err = mutex_lock_interruptible(&ha->drain_mutex); + if (err) + return err; + + set_bit(SAS_HA_DRAINING, &ha->state); + /* flush submitters */ + spin_lock_irq(&ha->state_lock); + spin_unlock_irq(&ha->state_lock); + + drain_workqueue(wq); + + spin_lock_irq(&ha->state_lock); + clear_bit(SAS_HA_DRAINING, &ha->state); + list_for_each_entry_safe(w, _w, &ha->defer_q, entry) { + list_del_init(&w->entry); + sas_queue_work(ha, w); + } + spin_unlock_irq(&ha->state_lock); + mutex_unlock(&ha->drain_mutex); + + return 0; +} +EXPORT_SYMBOL_GPL(sas_drain_work); + static void notify_ha_event(struct sas_ha_struct *sas_ha, enum ha_event event) { BUG_ON(event >= HA_NUM_EVENTS); diff --git a/drivers/scsi/libsas/sas_init.c b/drivers/scsi/libsas/sas_init.c index da244e68fe6f..572b943d7603 100644 --- a/drivers/scsi/libsas/sas_init.c +++ b/drivers/scsi/libsas/sas_init.c @@ -114,6 +114,8 @@ int sas_register_ha(struct sas_ha_struct *sas_ha) set_bit(SAS_HA_REGISTERED, &sas_ha->state); spin_lock_init(&sas_ha->state_lock); + mutex_init(&sas_ha->drain_mutex); + INIT_LIST_HEAD(&sas_ha->defer_q); error = sas_register_phys(sas_ha); if (error) { @@ -157,12 +159,13 @@ int sas_unregister_ha(struct sas_ha_struct *sas_ha) { unsigned long flags; - /* Set the state to unregistered to avoid further - * events to be queued */ + /* Set the state to unregistered to avoid further unchained + * events to be queued + */ spin_lock_irqsave(&sas_ha->state_lock, flags); clear_bit(SAS_HA_REGISTERED, &sas_ha->state); spin_unlock_irqrestore(&sas_ha->state_lock, flags); - scsi_flush_work(sas_ha->core.shost); + sas_drain_work(sas_ha); sas_unregister_ports(sas_ha); diff --git a/drivers/scsi/libsas/sas_internal.h b/drivers/scsi/libsas/sas_internal.h index 1fd84b3f091f..948ea64cc2eb 100644 --- a/drivers/scsi/libsas/sas_internal.h +++ b/drivers/scsi/libsas/sas_internal.h @@ -92,20 +92,6 @@ static inline int sas_smp_host_handler(struct Scsi_Host *shost, } #endif -static inline void sas_queue_event(int event, unsigned long *pending, - struct work_struct *work, - struct sas_ha_struct *sas_ha) -{ - if (!test_and_set_bit(event, pending)) { - unsigned long flags; - - spin_lock_irqsave(&sas_ha->state_lock, flags); - if (test_bit(SAS_HA_REGISTERED, &sas_ha->state)) - scsi_queue_work(sas_ha->core.shost, work); - spin_unlock_irqrestore(&sas_ha->state_lock, flags); - } -} - static inline void sas_fill_in_rphy(struct domain_device *dev, struct sas_rphy *rphy) { diff --git a/drivers/scsi/mvsas/mv_sas.c b/drivers/scsi/mvsas/mv_sas.c index a4884a57cf79..b118e632bc7d 100644 --- a/drivers/scsi/mvsas/mv_sas.c +++ b/drivers/scsi/mvsas/mv_sas.c @@ -308,7 +308,7 @@ int mvs_scan_finished(struct Scsi_Host *shost, unsigned long time) if (mvs_prv->scan_finished == 0) return 0; - scsi_flush_work(shost); + sas_drain_work(sha); return 1; } diff --git a/drivers/scsi/pm8001/pm8001_sas.c b/drivers/scsi/pm8001/pm8001_sas.c index 9589fc941a8b..50837933a1e5 100644 --- a/drivers/scsi/pm8001/pm8001_sas.c +++ b/drivers/scsi/pm8001/pm8001_sas.c @@ -256,12 +256,14 @@ void pm8001_scan_start(struct Scsi_Host *shost) int pm8001_scan_finished(struct Scsi_Host *shost, unsigned long time) { + struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost); + /* give the phy enabling interrupt event time to come in (1s * is empirically about all it takes) */ if (time < HZ) return 0; /* Wait for discovery to finish */ - scsi_flush_work(shost); + sas_drain_work(ha); return 1; } diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h index 8e402d5a0640..42900fa95a03 100644 --- a/include/scsi/libsas.h +++ b/include/scsi/libsas.h @@ -330,6 +330,7 @@ struct sas_ha_event { enum sas_ha_state { SAS_HA_REGISTERED, + SAS_HA_DRAINING, }; struct sas_ha_struct { @@ -337,6 +338,8 @@ struct sas_ha_struct { struct sas_ha_event ha_events[HA_NUM_EVENTS]; unsigned long pending; + struct list_head defer_q; /* work queued while draining */ + struct mutex drain_mutex; unsigned long state; spinlock_t state_lock; @@ -657,6 +660,7 @@ int sas_eh_bus_reset_handler(struct scsi_cmnd *cmd); extern void sas_target_destroy(struct scsi_target *); extern int sas_slave_alloc(struct scsi_device *); extern int sas_ioctl(struct scsi_device *sdev, int cmd, void __user *arg); +extern int sas_drain_work(struct sas_ha_struct *ha); extern int sas_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy, struct request *req); -- 2.20.1