[SCSI] libsas: remove ata_port.lock management duties from lldds

Each libsas driver (mvsas, pm8001, and isci) has invented a different
method for managing the ap->lock.  The lock is held by the ata
->queuecommand() path.  mvsas drops it prior to acquiring any internal
locks which allows it to hold its internal lock across calls to
task->task_done().  This capability is important as it is the only way
the driver can flush task->task_done() instances to guarantee that it no
longer has any in-flight references to a domain_device at
->lldd_dev_gone() time.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

2 files changed, 25 insertions, 17 deletions

diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 83118d0b6d0c..81ce39d166d1 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -166,23 +166,30 @@ qc_already_gone:
 
 static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
 {
-        int res;
+        unsigned long flags;
         struct sas_task *task;
-        struct domain_device *dev = qc->ap->private_data;
+        struct scatterlist *sg;
+        int ret = AC_ERR_SYSTEM;
+        unsigned int si, xfer = 0;
+        struct ata_port *ap = qc->ap;
+        struct domain_device *dev = ap->private_data;
         struct sas_ha_struct *sas_ha = dev->port->ha;
         struct Scsi_Host *host = sas_ha->core.shost;
         struct sas_internal *i = to_sas_internal(host->transportt);
-        struct scatterlist *sg;
-        unsigned int xfer = 0;
-        unsigned int si;
+
+        /* TODO: audit callers to ensure they are ready for qc_issue to
+         * unconditionally re-enable interrupts
+         */
+        local_irq_save(flags);
+        spin_unlock(ap->lock);
 
         /* If the device fell off, no sense in issuing commands */
         if (dev->gone)
-                return AC_ERR_SYSTEM;
+                goto out;
 
         task = sas_alloc_task(GFP_ATOMIC);
         if (!task)
-                return AC_ERR_SYSTEM;
+                goto out;
         task->dev = dev;
         task->task_proto = SAS_PROTOCOL_STP;
         task->task_done = sas_ata_task_done;
@@ -227,21 +234,24 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
                 ASSIGN_SAS_TASK(qc->scsicmd, task);
 
         if (sas_ha->lldd_max_execute_num < 2)
-                res = i->dft->lldd_execute_task(task, 1, GFP_ATOMIC);
+                ret = i->dft->lldd_execute_task(task, 1, GFP_ATOMIC);
         else
-                res = sas_queue_up(task);
+                ret = sas_queue_up(task);
 
         /* Examine */
-        if (res) {
-                SAS_DPRINTK("lldd_execute_task returned: %d\n", res);
+        if (ret) {
+                SAS_DPRINTK("lldd_execute_task returned: %d\n", ret);
 
                 if (qc->scsicmd)
                         ASSIGN_SAS_TASK(qc->scsicmd, NULL);
                 sas_free_task(task);
-                return AC_ERR_SYSTEM;
+                ret = AC_ERR_SYSTEM;
         }
 
-        return 0;
+ out:
+        spin_lock(ap->lock);
+        local_irq_restore(flags);
+        return ret;
 }
 
 static bool sas_ata_qc_fill_rtf(struct ata_queued_cmd *qc)
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 2a163c73fd8b..fd60465d4b2d 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -198,11 +198,9 @@ int sas_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
         }
 
         if (dev_is_sata(dev)) {
-                unsigned long flags;
-
-                spin_lock_irqsave(dev->sata_dev.ap->lock, flags);
+                spin_lock_irq(dev->sata_dev.ap->lock);
                 res = ata_sas_queuecmd(cmd, dev->sata_dev.ap);
-                spin_unlock_irqrestore(dev->sata_dev.ap->lock, flags);
+                spin_unlock_irq(dev->sata_dev.ap->lock);
                 return res;
         }