[set2 PATCH 0/4] libsas: eh routines vs eh context

[set2 PATCH 0/4] libsas: eh routines vs eh context

[Dan Williams]

Set2 of 5 patchsets to update scsi, libsas, and libata in
support of the isci driver.

The generic libsas eh handlers are called in many contexts, however lldd
implementations (isci in particular, but mvsas and pm8001 as well)
assume that they are only in eh context.  Make it safe for lldds to use
the generic helpers in all cases.

"libsas: add sas_eh_abort_handler" could be squashed with "isci: use sas
eh strategy handlers", but I left it separate since it needs enabling
(optional) per-lldd.

These have been in -next for the past couple kernel cycles.

---

Dan Williams (4):
      libsas: enforce eh strategy handlers only in eh context
      libsas: add sas_eh_abort_handler
      libsas: use ->lldd_I_T_nexus_reset for ->eh_bus_reset_handler
      isci: use sas eh strategy handlers


 drivers/scsi/isci/init.c            |    3 +
 drivers/scsi/libsas/sas_discover.c  |   11 ++
 drivers/scsi/libsas/sas_init.c      |    2 
 drivers/scsi/libsas/sas_scsi_host.c |  159 ++++++++++++++++++++++++++++++++---
 drivers/scsi/pm8001/pm8001_sas.c    |    3 -
 include/scsi/libsas.h               |   11 ++
 6 files changed, 174 insertions(+), 15 deletions(-)

[set2 PATCH 1/4] libsas: enforce eh strategy handlers only in eh context

[Dan Williams]

The strategy handlers may be called in places that are problematic for
libsas (i.e. sata resets outside of domain revalidation filtering /
libata link recovery), or problematic for userspace (non-blocking ioctl
to sleeping reset functions).  However, these routines are also called
for eh escalations and recovery of scsi_eh_prep_cmnd(), so permit them
as long as we are running in the host's error handler, otherwise arrange
for them to be triggered in eh_context.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/scsi/libsas/sas_discover.c  |   11 +++
 drivers/scsi/libsas/sas_init.c      |    2 +
 drivers/scsi/libsas/sas_scsi_host.c |  121 ++++++++++++++++++++++++++++++++++-
 include/scsi/libsas.h               |   10 +++
 4 files changed, 140 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index ff497ac..b031d23 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -39,6 +39,7 @@ void sas_init_dev(struct domain_device *dev)
 {
 	switch (dev->dev_type) {
 	case SAS_END_DEV:
+		INIT_LIST_HEAD(&dev->ssp_dev.eh_list_node);
 		break;
 	case EDGE_DEV:
 	case FANOUT_DEV:
@@ -286,6 +287,8 @@ void sas_free_device(struct kref *kref)
 
 static void sas_unregister_common_dev(struct asd_sas_port *port, struct domain_device *dev)
 {
+	struct sas_ha_struct *ha = port->ha;
+
 	sas_notify_lldd_dev_gone(dev);
 	if (!dev->parent)
 		dev->port->port_dev = NULL;
@@ -298,6 +301,14 @@ static void sas_unregister_common_dev(struct asd_sas_port *port, struct domain_d
 		sas_ata_end_eh(dev->sata_dev.ap);
 	spin_unlock_irq(&port->dev_list_lock);
 
+	spin_lock_irq(&ha->lock);
+	if (dev->dev_type == SAS_END_DEV &&
+	    !list_empty(&dev->ssp_dev.eh_list_node)) {
+		list_del_init(&dev->ssp_dev.eh_list_node);
+		ha->eh_active--;
+	}
+	spin_unlock_irq(&ha->lock);
+
 	sas_put_device(dev);
 }
 
diff --git a/drivers/scsi/libsas/sas_init.c b/drivers/scsi/libsas/sas_init.c
index 6909fef..1bbab3d 100644
--- a/drivers/scsi/libsas/sas_init.c
+++ b/drivers/scsi/libsas/sas_init.c
@@ -116,7 +116,9 @@ int sas_register_ha(struct sas_ha_struct *sas_ha)
 	set_bit(SAS_HA_REGISTERED, &sas_ha->state);
 	spin_lock_init(&sas_ha->lock);
 	mutex_init(&sas_ha->drain_mutex);
+	init_waitqueue_head(&sas_ha->eh_wait_q);
 	INIT_LIST_HEAD(&sas_ha->defer_q);
+	INIT_LIST_HEAD(&sas_ha->eh_dev_q);
 
 	error = sas_register_phys(sas_ha);
 	if (error) {
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 52d5b01..2e0e779 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -460,14 +460,88 @@ struct sas_phy *sas_get_local_phy(struct domain_device *dev)
 }
 EXPORT_SYMBOL_GPL(sas_get_local_phy);
 
+static void sas_wait_eh(struct domain_device *dev)
+{
+	struct sas_ha_struct *ha = dev->port->ha;
+	DEFINE_WAIT(wait);
+
+	if (dev_is_sata(dev)) {
+		ata_port_wait_eh(dev->sata_dev.ap);
+		return;
+	}
+ retry:
+	spin_lock_irq(&ha->lock);
+
+	while (test_bit(SAS_DEV_EH_PENDING, &dev->state)) {
+		prepare_to_wait(&ha->eh_wait_q, &wait, TASK_UNINTERRUPTIBLE);
+		spin_unlock_irq(&ha->lock);
+		schedule();
+		spin_lock_irq(&ha->lock);
+	}
+	finish_wait(&ha->eh_wait_q, &wait);
+
+	spin_unlock_irq(&ha->lock);
+
+	/* make sure SCSI EH is complete */
+	if (scsi_host_in_recovery(ha->core.shost)) {
+		msleep(10);
+		goto retry;
+	}
+}
+EXPORT_SYMBOL(sas_wait_eh);
+
+static int sas_queue_reset(struct domain_device *dev, int reset_type, int lun, int wait)
+{
+	struct sas_ha_struct *ha = dev->port->ha;
+	int scheduled = 0, tries = 100;
+
+	/* ata: promote lun reset to bus reset */
+	if (dev_is_sata(dev)) {
+		sas_ata_schedule_reset(dev);
+		if (wait)
+			sas_ata_wait_eh(dev);
+		return SUCCESS;
+	}
+
+	while (!scheduled && tries--) {
+		spin_lock_irq(&ha->lock);
+		if (!test_bit(SAS_DEV_EH_PENDING, &dev->state) &&
+		    !test_bit(reset_type, &dev->state)) {
+			scheduled = 1;
+			ha->eh_active++;
+			list_add_tail(&dev->ssp_dev.eh_list_node, &ha->eh_dev_q);
+			set_bit(SAS_DEV_EH_PENDING, &dev->state);
+			set_bit(reset_type, &dev->state);
+			int_to_scsilun(lun, &dev->ssp_dev.reset_lun);
+			scsi_schedule_eh(ha->core.shost);
+		}
+		spin_unlock_irq(&ha->lock);
+
+		if (wait)
+			sas_wait_eh(dev);
+
+		if (scheduled)
+			return SUCCESS;
+	}
+
+	SAS_DPRINTK("%s reset of %s failed\n",
+		    reset_type == SAS_DEV_LU_RESET ? "LUN" : "Bus",
+		    dev_name(&dev->rphy->dev));
+
+	return FAILED;
+}
+
 /* Attempt to send a LUN reset message to a device */
 int sas_eh_device_reset_handler(struct scsi_cmnd *cmd)
 {
-	struct domain_device *dev = cmd_to_domain_dev(cmd);
-	struct sas_internal *i =
-		to_sas_internal(dev->port->ha->core.shost->transportt);
-	struct scsi_lun lun;
 	int res;
+	struct scsi_lun lun;
+	struct Scsi_Host *host = cmd->device->host;
+	struct domain_device *dev = cmd_to_domain_dev(cmd);
+	struct sas_internal *i = to_sas_internal(host->transportt);
+
+	if (current != host->ehandler)
+		return sas_queue_reset(dev, SAS_DEV_LU_RESET, cmd->device->lun, 0);
 
 	int_to_scsilun(cmd->device->lun, &lun);
 
@@ -486,8 +560,12 @@ int sas_eh_bus_reset_handler(struct scsi_cmnd *cmd)
 {
 	struct domain_device *dev = cmd_to_domain_dev(cmd);
 	struct sas_phy *phy = sas_get_local_phy(dev);
+	struct Scsi_Host *host = cmd->device->host;
 	int res;
 
+	if (current != host->ehandler)
+		return sas_queue_reset(dev, SAS_DEV_RESET, 0, 0);
+
 	res = sas_phy_reset(phy, 1);
 	if (res)
 		SAS_DPRINTK("Bus reset of %s failed 0x%x\n",
@@ -667,6 +745,39 @@ static void sas_eh_handle_sas_errors(struct Scsi_Host *shost, struct list_head *
 	goto out;
 }
 
+static void sas_eh_handle_resets(struct Scsi_Host *shost)
+{
+	struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
+	struct sas_internal *i = to_sas_internal(shost->transportt);
+
+	/* handle directed resets to sas devices */
+	spin_lock_irq(&ha->lock);
+	while (!list_empty(&ha->eh_dev_q)) {
+		struct domain_device *dev;
+		struct ssp_device *ssp;
+
+		ssp = list_entry(ha->eh_dev_q.next, typeof(*ssp), eh_list_node);
+		list_del_init(&ssp->eh_list_node);
+		dev = container_of(ssp, typeof(*dev), ssp_dev);
+		kref_get(&dev->kref);
+		WARN_ONCE(dev_is_sata(dev), "ssp reset to ata device?\n");
+
+		spin_unlock_irq(&ha->lock);
+
+		if (test_and_clear_bit(SAS_DEV_LU_RESET, &dev->state))
+			i->dft->lldd_lu_reset(dev, ssp->reset_lun.scsi_lun);
+
+		if (test_and_clear_bit(SAS_DEV_RESET, &dev->state))
+			i->dft->lldd_I_T_nexus_reset(dev);
+
+		sas_put_device(dev);
+		spin_lock_irq(&ha->lock);
+		clear_bit(SAS_DEV_EH_PENDING, &dev->state);
+		ha->eh_active--;
+	}
+	spin_unlock_irq(&ha->lock);
+}
+
 
 void sas_scsi_recover_host(struct Scsi_Host *shost)
 {
@@ -709,6 +820,8 @@ out:
 	if (ha->lldd_max_execute_num > 1)
 		wake_up_process(ha->core.queue_thread);
 
+	sas_eh_handle_resets(shost);
+
 	/* now link into libata eh --- if we have any ata devices */
 	sas_ata_strategy_handler(shost);
 
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index 2718b24..ade862a 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -174,10 +174,17 @@ struct sata_device {
 	struct ata_taskfile tf;
 };
 
+struct ssp_device {
+	struct list_head eh_list_node; /* pending a user requested eh action */
+	struct scsi_lun reset_lun;
+};
+
 enum {
 	SAS_DEV_GONE,
 	SAS_DEV_DESTROY,
 	SAS_DEV_EH_PENDING,
+	SAS_DEV_LU_RESET,
+	SAS_DEV_RESET,
 };
 
 struct domain_device {
@@ -211,6 +218,7 @@ struct domain_device {
         union {
                 struct expander_device ex_dev;
                 struct sata_device     sata_dev; /* STP & directly attached */
+		struct ssp_device      ssp_dev;
         };
 
         void *lldd_dev;
@@ -387,6 +395,8 @@ struct sas_ha_struct {
 	unsigned long	  state;
 	spinlock_t	  lock;
 	int		  eh_active;
+	wait_queue_head_t eh_wait_q;
+	struct list_head  eh_dev_q;
 
 	struct mutex disco_mutex;
 

[set2 PATCH 2/4] libsas: add sas_eh_abort_handler

[Dan Williams]

When recovering failed eh-cmnds let the lldd attempt an abort via
scsi_abort_eh_cmnd before escalating.

Reviewed-by: Jacek Danecki <jacek.danecki@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/scsi/libsas/sas_scsi_host.c |   21 +++++++++++++++++++++
 include/scsi/libsas.h               |    1 +
 2 files changed, 22 insertions(+)

diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 2e0e779..875b871 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -531,6 +531,27 @@ static int sas_queue_reset(struct domain_device *dev, int reset_type, int lun, i
 	return FAILED;
 }
 
+int sas_eh_abort_handler(struct scsi_cmnd *cmd)
+{
+	int res;
+	struct sas_task *task = TO_SAS_TASK(cmd);
+	struct Scsi_Host *host = cmd->device->host;
+	struct sas_internal *i = to_sas_internal(host->transportt);
+
+	if (current != host->ehandler)
+		return FAILED;
+
+	if (!i->dft->lldd_abort_task)
+		return FAILED;
+
+	res = i->dft->lldd_abort_task(task);
+	if (res == TMF_RESP_FUNC_SUCC || res == TMF_RESP_FUNC_COMPLETE)
+		return SUCCESS;
+
+	return FAILED;
+}
+EXPORT_SYMBOL_GPL(sas_eh_abort_handler);
+
 /* Attempt to send a LUN reset message to a device */
 int sas_eh_device_reset_handler(struct scsi_cmnd *cmd)
 {
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index ade862a..7c4bd08 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -718,6 +718,7 @@ void sas_unregister_dev(struct asd_sas_port *port, struct domain_device *);
 void sas_init_dev(struct domain_device *);
 
 void sas_task_abort(struct sas_task *);
+int sas_eh_abort_handler(struct scsi_cmnd *cmd);
 int sas_eh_device_reset_handler(struct scsi_cmnd *cmd);
 int sas_eh_bus_reset_handler(struct scsi_cmnd *cmd);
 

[set2 PATCH 3/4] libsas: use ->lldd_I_T_nexus_reset for ->eh_bus_reset_handler

[Dan Williams]

sas_eh_bus_reset_handler() amounts to sas_phy_reset() without
notification of the reset to the lldd.  If this is triggered from
eh-cmnd recovery there may be sas_tasks for the lldd to terminate, so
->lldd_I_T_nexus_reset is warranted.

Cc: Xiangliang Yu <yuxiangl@marvell.com>
Cc: Luben Tuikov <ltuikov@yahoo.com>
Cc: Jack Wang <jack_wang@usish.com>
Reviewed-by: Jacek Danecki <jacek.danecki@intel.com>
[jacek: modify pm8001_I_T_nexus_reset to return -ENODEV]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/scsi/libsas/sas_scsi_host.c |   19 ++++++++-----------
 drivers/scsi/pm8001/pm8001_sas.c    |    3 ++-
 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 875b871..6764148 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -576,25 +576,22 @@ int sas_eh_device_reset_handler(struct scsi_cmnd *cmd)
 	return FAILED;
 }
 
-/* Attempt to send a phy (bus) reset */
 int sas_eh_bus_reset_handler(struct scsi_cmnd *cmd)
 {
-	struct domain_device *dev = cmd_to_domain_dev(cmd);
-	struct sas_phy *phy = sas_get_local_phy(dev);
-	struct Scsi_Host *host = cmd->device->host;
 	int res;
+	struct Scsi_Host *host = cmd->device->host;
+	struct domain_device *dev = cmd_to_domain_dev(cmd);
+	struct sas_internal *i = to_sas_internal(host->transportt);
 
 	if (current != host->ehandler)
 		return sas_queue_reset(dev, SAS_DEV_RESET, 0, 0);
 
-	res = sas_phy_reset(phy, 1);
-	if (res)
-		SAS_DPRINTK("Bus reset of %s failed 0x%x\n",
-			    kobject_name(&phy->dev.kobj),
-			    res);
-	sas_put_local_phy(phy);
+	if (!i->dft->lldd_I_T_nexus_reset)
+		return FAILED;
 
-	if (res == TMF_RESP_FUNC_SUCC || res == TMF_RESP_FUNC_COMPLETE)
+	res = i->dft->lldd_I_T_nexus_reset(dev);
+	if (res == TMF_RESP_FUNC_SUCC || res == TMF_RESP_FUNC_COMPLETE ||
+	    res == -ENODEV)
 		return SUCCESS;
 
 	return FAILED;
diff --git a/drivers/scsi/pm8001/pm8001_sas.c b/drivers/scsi/pm8001/pm8001_sas.c
index 3b11edd..fdbba57 100644
--- a/drivers/scsi/pm8001/pm8001_sas.c
+++ b/drivers/scsi/pm8001/pm8001_sas.c
@@ -962,8 +962,9 @@ int pm8001_I_T_nexus_reset(struct domain_device *dev)
 	struct pm8001_device *pm8001_dev;
 	struct pm8001_hba_info *pm8001_ha;
 	struct sas_phy *phy;
+
 	if (!dev || !dev->lldd_dev)
-		return -1;
+		return -ENODEV;
 
 	pm8001_dev = dev->lldd_dev;
 	pm8001_ha = pm8001_find_ha_by_dev(dev);

[set2 PATCH 4/4] isci: use sas eh strategy handlers

[Dan Williams]

...now that the strategy handlers guarantee eh context and notify
the driver of bus reset.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/scsi/isci/init.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/scsi/isci/init.c b/drivers/scsi/isci/init.c
index 47e28b5..92c1d86 100644
--- a/drivers/scsi/isci/init.c
+++ b/drivers/scsi/isci/init.c
@@ -166,6 +166,9 @@ static struct scsi_host_template isci_sht = {
 	.sg_tablesize			= SG_ALL,
 	.max_sectors			= SCSI_DEFAULT_MAX_SECTORS,
 	.use_clustering			= ENABLE_CLUSTERING,
+	.eh_abort_handler		= sas_eh_abort_handler,
+	.eh_device_reset_handler        = sas_eh_device_reset_handler,
+	.eh_bus_reset_handler           = sas_eh_bus_reset_handler,
 	.target_destroy			= sas_target_destroy,
 	.ioctl				= sas_ioctl,
 	.shost_attrs			= isci_host_attrs,