[SCSI] libata, libsas: introduce sched_eh and end_eh port ops

When managing shost->host_eh_scheduled libata assumes that there is a
1:1 shost-to-ata_port relationship.  libsas creates a 1:N relationship
so it needs to manage host_eh_scheduled cumulatively at the host level.
The sched_eh and end_eh port port ops allow libsas to track when domain
devices enter/leave the "eh-pending" state under ha->lock (previously
named ha->state_lock, but it is no longer just a lock for ha->state
changes).

Since host_eh_scheduled indicates eh without backing commands pinning
the device it can be deallocated at any time.  Move the taking of the
domain_device reference under the port_lock to guarantee that the
ata_port stays around for the duration of eh.

Reviewed-by: Jacek Danecki <jacek.danecki@intel.com>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

10 files changed, 134 insertions, 37 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index cece3a4d11ea..3fe1202c61ce 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -80,6 +80,8 @@ const struct ata_port_operations ata_base_port_ops = {
         .prereset               = ata_std_prereset,
         .postreset              = ata_std_postreset,
         .error_handler          = ata_std_error_handler,
+        .sched_eh               = ata_std_sched_eh,
+        .end_eh                 = ata_std_end_eh,
 };
 
 const struct ata_port_operations sata_port_ops = {
@@ -6642,6 +6644,8 @@ struct ata_port_operations ata_dummy_port_ops = {
         .qc_prep                = ata_noop_qc_prep,
         .qc_issue               = ata_dummy_qc_issue,
         .error_handler          = ata_dummy_error_handler,
+        .sched_eh               = ata_std_sched_eh,
+        .end_eh                 = ata_std_end_eh,
 };
 
 const struct ata_port_info ata_dummy_port_info = {
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 6d53cf9b3b6e..77fc80640e26 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -793,12 +793,12 @@ void ata_scsi_port_error_handler(struct Scsi_Host *host, struct ata_port *ap)
                 ata_for_each_link(link, ap, HOST_FIRST)
                         memset(&link->eh_info, 0, sizeof(link->eh_info));
 
-                /* Clear host_eh_scheduled while holding ap->lock such
-                 * that if exception occurs after this point but
-                 * before EH completion, SCSI midlayer will
+                /* end eh (clear host_eh_scheduled) while holding
+                 * ap->lock such that if exception occurs after this
+                 * point but before EH completion, SCSI midlayer will
                  * re-initiate EH.
                  */
-                host->host_eh_scheduled = 0;
+                ap->ops->end_eh(ap);
 
                 spin_unlock_irqrestore(ap->lock, flags);
                 ata_eh_release(ap);
@@ -986,16 +986,13 @@ void ata_qc_schedule_eh(struct ata_queued_cmd *qc)
 }
 
 /**
- *      ata_port_schedule_eh - schedule error handling without a qc
- *      @ap: ATA port to schedule EH for
- *
- *      Schedule error handling for @ap.  EH will kick in as soon as
- *      all commands are drained.
+ * ata_std_sched_eh - non-libsas ata_ports issue eh with this common routine
+ * @ap: ATA port to schedule EH for
  *
- *      LOCKING:
+ *      LOCKING: inherited from ata_port_schedule_eh
  *      spin_lock_irqsave(host lock)
  */
-void ata_port_schedule_eh(struct ata_port *ap)
+void ata_std_sched_eh(struct ata_port *ap)
 {
         WARN_ON(!ap->ops->error_handler);
 
@@ -1007,6 +1004,44 @@ void ata_port_schedule_eh(struct ata_port *ap)
 
         DPRINTK("port EH scheduled\n");
 }
+EXPORT_SYMBOL_GPL(ata_std_sched_eh);
+
+/**
+ * ata_std_end_eh - non-libsas ata_ports complete eh with this common routine
+ * @ap: ATA port to end EH for
+ *
+ * In the libata object model there is a 1:1 mapping of ata_port to
+ * shost, so host fields can be directly manipulated under ap->lock, in
+ * the libsas case we need to hold a lock at the ha->level to coordinate
+ * these events.
+ *
+ *      LOCKING:
+ *      spin_lock_irqsave(host lock)
+ */
+void ata_std_end_eh(struct ata_port *ap)
+{
+        struct Scsi_Host *host = ap->scsi_host;
+
+        host->host_eh_scheduled = 0;
+}
+EXPORT_SYMBOL(ata_std_end_eh);
+
+
+/**
+ *      ata_port_schedule_eh - schedule error handling without a qc
+ *      @ap: ATA port to schedule EH for
+ *
+ *      Schedule error handling for @ap.  EH will kick in as soon as
+ *      all commands are drained.
+ *
+ *      LOCKING:
+ *      spin_lock_irqsave(host lock)
+ */
+void ata_port_schedule_eh(struct ata_port *ap)
+{
+        /* see: ata_std_sched_eh, unless you know better */
+        ap->ops->sched_eh(ap);
+}
 
 static int ata_do_link_abort(struct ata_port *ap, struct ata_link *link)
 {
diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index d109cc3a17b6..b035acf18730 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -523,6 +523,31 @@ static void sas_ata_set_dmamode(struct ata_port *ap, struct ata_device *ata_dev)
                 i->dft->lldd_ata_set_dmamode(dev);
 }
 
+static void sas_ata_sched_eh(struct ata_port *ap)
+{
+        struct domain_device *dev = ap->private_data;
+        struct sas_ha_struct *ha = dev->port->ha;
+        unsigned long flags;
+
+        spin_lock_irqsave(&ha->lock, flags);
+        if (!test_and_set_bit(SAS_DEV_EH_PENDING, &dev->state))
+                ha->eh_active++;
+        ata_std_sched_eh(ap);
+        spin_unlock_irqrestore(&ha->lock, flags);
+}
+
+void sas_ata_end_eh(struct ata_port *ap)
+{
+        struct domain_device *dev = ap->private_data;
+        struct sas_ha_struct *ha = dev->port->ha;
+        unsigned long flags;
+
+        spin_lock_irqsave(&ha->lock, flags);
+        if (test_and_clear_bit(SAS_DEV_EH_PENDING, &dev->state))
+                ha->eh_active--;
+        spin_unlock_irqrestore(&ha->lock, flags);
+}
+
 static struct ata_port_operations sas_sata_ops = {
         .prereset               = ata_std_prereset,
         .hardreset              = sas_ata_hard_reset,
@@ -536,6 +561,8 @@ static struct ata_port_operations sas_sata_ops = {
         .port_start             = ata_sas_port_start,
         .port_stop              = ata_sas_port_stop,
         .set_dmamode            = sas_ata_set_dmamode,
+        .sched_eh               = sas_ata_sched_eh,
+        .end_eh                 = sas_ata_end_eh,
 };
 
 static struct ata_port_info sata_port_info = {
@@ -708,10 +735,6 @@ static void async_sas_ata_eh(void *data, async_cookie_t cookie)
         struct ata_port *ap = dev->sata_dev.ap;
         struct sas_ha_struct *ha = dev->port->ha;
 
-        /* hold a reference over eh since we may be racing with final
-         * remove once all commands are completed
-         */
-        kref_get(&dev->kref);
         sas_ata_printk(KERN_DEBUG, dev, "dev error handler\n");
         ata_scsi_port_error_handler(ha->core.shost, ap);
         sas_put_device(dev);
@@ -742,6 +765,13 @@ void sas_ata_strategy_handler(struct Scsi_Host *shost)
                 list_for_each_entry(dev, &port->dev_list, dev_list_node) {
                         if (!dev_is_sata(dev))
                                 continue;
+
+                        /* hold a reference over eh since we may be
+                         * racing with final remove once all commands
+                         * are completed
+                         */
+                        kref_get(&dev->kref);
+
                         async_schedule_domain(async_sas_ata_eh, dev, &async);
                 }
                 spin_unlock(&port->dev_list_lock);
diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index 629a0865b130..ff497ac76cb4 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -294,6 +294,8 @@ static void sas_unregister_common_dev(struct asd_sas_port *port, struct domain_d
 
         spin_lock_irq(&port->dev_list_lock);
         list_del_init(&dev->dev_list_node);
+        if (dev_is_sata(dev))
+                sas_ata_end_eh(dev->sata_dev.ap);
         spin_unlock_irq(&port->dev_list_lock);
 
         sas_put_device(dev);
@@ -488,9 +490,9 @@ static void sas_chain_event(int event, unsigned long *pending,
         if (!test_and_set_bit(event, pending)) {
                 unsigned long flags;
 
-                spin_lock_irqsave(&ha->state_lock, flags);
+                spin_lock_irqsave(&ha->lock, flags);
                 sas_chain_work(ha, sw);
-                spin_unlock_irqrestore(&ha->state_lock, flags);
+                spin_unlock_irqrestore(&ha->lock, flags);
         }
 }
 
diff --git a/drivers/scsi/libsas/sas_event.c b/drivers/scsi/libsas/sas_event.c
index 4e4292d210c1..789c4d8bb7a7 100644
--- a/drivers/scsi/libsas/sas_event.c
+++ b/drivers/scsi/libsas/sas_event.c
@@ -47,9 +47,9 @@ static void sas_queue_event(int event, unsigned long *pending,
         if (!test_and_set_bit(event, pending)) {
                 unsigned long flags;
 
-                spin_lock_irqsave(&ha->state_lock, flags);
+                spin_lock_irqsave(&ha->lock, flags);
                 sas_queue_work(ha, work);
-                spin_unlock_irqrestore(&ha->state_lock, flags);
+                spin_unlock_irqrestore(&ha->lock, flags);
         }
 }
 
@@ -61,18 +61,18 @@ void __sas_drain_work(struct sas_ha_struct *ha)
 
         set_bit(SAS_HA_DRAINING, &ha->state);
         /* flush submitters */
-        spin_lock_irq(&ha->state_lock);
-        spin_unlock_irq(&ha->state_lock);
+        spin_lock_irq(&ha->lock);
+        spin_unlock_irq(&ha->lock);
 
         drain_workqueue(wq);
 
-        spin_lock_irq(&ha->state_lock);
+        spin_lock_irq(&ha->lock);
         clear_bit(SAS_HA_DRAINING, &ha->state);
         list_for_each_entry_safe(sw, _sw, &ha->defer_q, drain_node) {
                 list_del_init(&sw->drain_node);
                 sas_queue_work(ha, sw);
         }
-        spin_unlock_irq(&ha->state_lock);
+        spin_unlock_irq(&ha->lock);
 }
 
 int sas_drain_work(struct sas_ha_struct *ha)
diff --git a/drivers/scsi/libsas/sas_init.c b/drivers/scsi/libsas/sas_init.c
index 10cb5ae30977..6909fefa32c5 100644
--- a/drivers/scsi/libsas/sas_init.c
+++ b/drivers/scsi/libsas/sas_init.c
@@ -114,7 +114,7 @@ int sas_register_ha(struct sas_ha_struct *sas_ha)
                 sas_ha->lldd_queue_size = 128; /* Sanity */
 
         set_bit(SAS_HA_REGISTERED, &sas_ha->state);
-        spin_lock_init(&sas_ha->state_lock);
+        spin_lock_init(&sas_ha->lock);
         mutex_init(&sas_ha->drain_mutex);
         INIT_LIST_HEAD(&sas_ha->defer_q);
 
@@ -163,9 +163,9 @@ int sas_unregister_ha(struct sas_ha_struct *sas_ha)
          * events to be queued, and flush any in-progress drainers
          */
         mutex_lock(&sas_ha->drain_mutex);
-        spin_lock_irq(&sas_ha->state_lock);
+        spin_lock_irq(&sas_ha->lock);
         clear_bit(SAS_HA_REGISTERED, &sas_ha->state);
-        spin_unlock_irq(&sas_ha->state_lock);
+        spin_unlock_irq(&sas_ha->lock);
         __sas_drain_work(sas_ha);
         mutex_unlock(&sas_ha->drain_mutex);
 
@@ -411,9 +411,9 @@ static int queue_phy_reset(struct sas_phy *phy, int hard_reset)
         d->reset_result = 0;
         d->hard_reset = hard_reset;
 
-        spin_lock_irq(&ha->state_lock);
+        spin_lock_irq(&ha->lock);
         sas_queue_work(ha, &d->reset_work);
-        spin_unlock_irq(&ha->state_lock);
+        spin_unlock_irq(&ha->lock);
 
         rc = sas_drain_work(ha);
         if (rc == 0)
@@ -438,9 +438,9 @@ static int queue_phy_enable(struct sas_phy *phy, int enable)
         d->enable_result = 0;
         d->enable = enable;
 
-        spin_lock_irq(&ha->state_lock);
+        spin_lock_irq(&ha->lock);
         sas_queue_work(ha, &d->enable_work);
-        spin_unlock_irq(&ha->state_lock);
+        spin_unlock_irq(&ha->lock);
 
         rc = sas_drain_work(ha);
         if (rc == 0)
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index f0b9b7bf1882..a09da44e282b 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -667,16 +667,20 @@ static void sas_eh_handle_sas_errors(struct Scsi_Host *shost, struct list_head *
         goto out;
 }
 
+
 void sas_scsi_recover_host(struct Scsi_Host *shost)
 {
         struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
-        unsigned long flags;
         LIST_HEAD(eh_work_q);
+        int tries = 0;
+        bool retry;
 
-        spin_lock_irqsave(shost->host_lock, flags);
+retry:
+        tries++;
+        retry = true;
+        spin_lock_irq(shost->host_lock);
         list_splice_init(&shost->eh_cmd_q, &eh_work_q);
-        shost->host_eh_scheduled = 0;
-        spin_unlock_irqrestore(shost->host_lock, flags);
+        spin_unlock_irq(shost->host_lock);
 
         SAS_DPRINTK("Enter %s busy: %d failed: %d\n",
                     __func__, shost->host_busy, shost->host_failed);
@@ -710,8 +714,19 @@ out:
 
         scsi_eh_flush_done_q(&ha->eh_done_q);
 
-        SAS_DPRINTK("--- Exit %s: busy: %d failed: %d\n",
-                    __func__, shost->host_busy, shost->host_failed);
+        /* check if any new eh work was scheduled during the last run */
+        spin_lock_irq(&ha->lock);
+        if (ha->eh_active == 0) {
+                shost->host_eh_scheduled = 0;
+                retry = false;
+        }
+        spin_unlock_irq(&ha->lock);
+
+        if (retry)
+                goto retry;
+
+        SAS_DPRINTK("--- Exit %s: busy: %d failed: %d tries: %d\n",
+                    __func__, shost->host_busy, shost->host_failed, tries);
 }
 
 enum blk_eh_timer_return sas_scsi_timed_out(struct scsi_cmnd *cmd)
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 6e887c742a27..53da442f892d 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -846,6 +846,8 @@ struct ata_port_operations {
         void (*error_handler)(struct ata_port *ap);
         void (*lost_interrupt)(struct ata_port *ap);
         void (*post_internal_cmd)(struct ata_queued_cmd *qc);
+        void (*sched_eh)(struct ata_port *ap);
+        void (*end_eh)(struct ata_port *ap);
 
         /*
          * Optional features
@@ -1167,6 +1169,8 @@ extern void ata_do_eh(struct ata_port *ap, ata_prereset_fn_t prereset,
                       ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
                       ata_postreset_fn_t postreset);
 extern void ata_std_error_handler(struct ata_port *ap);
+extern void ata_std_sched_eh(struct ata_port *ap);
+extern void ata_std_end_eh(struct ata_port *ap);
 extern int ata_link_nr_enabled(struct ata_link *link);
 
 /*
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index 10ce74f589c5..814d8cb592ad 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -179,6 +179,7 @@ struct sata_device {
 enum {
         SAS_DEV_GONE,
         SAS_DEV_DESTROY,
+        SAS_DEV_EH_PENDING,
 };
 
 struct domain_device {
@@ -386,7 +387,8 @@ struct sas_ha_struct {
         struct list_head  defer_q; /* work queued while draining */
         struct mutex      drain_mutex;
         unsigned long     state;
-        spinlock_t        state_lock;
+        spinlock_t        lock;
+        int               eh_active;
 
         struct mutex disco_mutex;
 
diff --git a/include/scsi/sas_ata.h b/include/scsi/sas_ata.h
index 77670e823ed8..2dfbdaa0b34a 100644
--- a/include/scsi/sas_ata.h
+++ b/include/scsi/sas_ata.h
@@ -45,6 +45,7 @@ void sas_ata_eh(struct Scsi_Host *shost, struct list_head *work_q,
 void sas_ata_schedule_reset(struct domain_device *dev);
 void sas_ata_wait_eh(struct domain_device *dev);
 void sas_probe_sata(struct asd_sas_port *port);
+void sas_ata_end_eh(struct ata_port *ap);
 #else
 
 
@@ -85,6 +86,10 @@ static inline int sas_get_ata_info(struct domain_device *dev, struct ex_phy *phy
 {
         return 0;
 }
+
+static inline void sas_ata_end_eh(struct ata_port *ap)
+{
+}
 #endif
 
 #endif /* _SAS_ATA_H_ */