[SCSI] libsas: enforce eh strategy handlers only in eh context

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>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index ff497ac..b031d23 100644 (file)
--- 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 (file)
--- 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 (file)
--- 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 814d8cb..df9cefd 100644 (file)
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -176,10 +176,17 @@ struct sata_device {
        u8     fis[ATA_RESP_FIS_SIZE];
 };
 
+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 {
@@ -213,6 +220,7 @@ 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;
@@ -389,6 +397,8 @@ 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;