isci: kill isci_remote_device_change_state()

Now that "stopping/stopped" are one in the same and signalled by a NULL device
pointer the rest of the device status infrastructure can be removed (->status
and ->state_lock).  The "not ready for i/o state" is replaced with a state
flag, and is evaluated under scic_lock so that we don't see transients from
taking the device reference to submitting the i/o.

This also fixes a potential leakage of can_queue slots in the rare case that
SAS_TASK_ABORTED is set at submission.

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

1 files changed, 22 insertions, 46 deletions

diff --git a/drivers/scsi/isci/task.c b/drivers/scsi/isci/task.c
index dd5e9de1ffb5..c313bc16c218 100644
--- a/drivers/scsi/isci/task.c
+++ b/drivers/scsi/isci/task.c
@@ -147,10 +147,10 @@ int isci_task_execute_task(struct sas_task *task, int num, gfp_t gfp_flags)
 {
         struct isci_host *ihost = dev_to_ihost(task->dev);
         struct isci_remote_device *idev;
+        enum sci_status status;
         unsigned long flags;
+        bool io_ready;
         int ret;
-        enum sci_status status;
-        enum isci_status device_status;
 
         dev_dbg(&ihost->pdev->dev, "%s: num=%d\n", __func__, num);
 
@@ -163,64 +163,40 @@ int isci_task_execute_task(struct sas_task *task, int num, gfp_t gfp_flags)
         }
 
         for_each_sas_task(num, task) {
-                dev_dbg(&ihost->pdev->dev,
-                        "task = %p, num = %d; dev = %p; cmd = %p\n",
-                            task, num, task->dev, task->uldd_task);
                 spin_lock_irqsave(&ihost->scic_lock, flags);
                 idev = isci_lookup_device(task->dev);
+                io_ready = idev ? test_bit(IDEV_IO_READY, &idev->flags) : 0;
                 spin_unlock_irqrestore(&ihost->scic_lock, flags);
 
-                if (idev)
-                        device_status = idev->status;
-                else
-                        device_status = isci_freed;
-
-                /* From this point onward, any process that needs to guarantee
-                 * that there is no kernel I/O being started will have to wait
-                 * for the quiesce spinlock.
-                 */
-
-                if (device_status != isci_ready_for_io) {
+                dev_dbg(&ihost->pdev->dev,
+                        "task: %p, num: %d dev: %p idev: %p:%#lx cmd = %p\n",
+                        task, num, task->dev, idev, idev ? idev->flags : 0,
+                        task->uldd_task);
 
-                        /* Forces a retry from scsi mid layer. */
-                        dev_dbg(&ihost->pdev->dev,
-                                "%s: task %p: isci_host->status = %d, "
-                                "device = %p; device_status = 0x%x\n\n",
-                                __func__,
-                                task,
-                                isci_host_get_state(ihost),
-                                idev,
-                                device_status);
-
-                        if (device_status == isci_ready) {
-                                /* Indicate QUEUE_FULL so that the scsi midlayer
-                                * retries.
-                                */
-                                isci_task_refuse(ihost, task,
-                                                 SAS_TASK_COMPLETE,
-                                                 SAS_QUEUE_FULL);
-                        } else {
-                                /* Else, the device is going down. */
-                                isci_task_refuse(ihost, task,
-                                                 SAS_TASK_UNDELIVERED,
-                                                 SAS_DEVICE_UNKNOWN);
-                        }
+                if (!idev) {
+                        isci_task_refuse(ihost, task, SAS_TASK_UNDELIVERED,
+                                         SAS_DEVICE_UNKNOWN);
+                        isci_host_can_dequeue(ihost, 1);
+                } else if (!io_ready) {
+                        /* Indicate QUEUE_FULL so that the scsi midlayer
+                         * retries.
+                          */
+                        isci_task_refuse(ihost, task, SAS_TASK_COMPLETE,
+                                         SAS_QUEUE_FULL);
                         isci_host_can_dequeue(ihost, 1);
                 } else {
                         /* There is a device and it's ready for I/O. */
                         spin_lock_irqsave(&task->task_state_lock, flags);
 
                         if (task->task_state_flags & SAS_TASK_STATE_ABORTED) {
-
+                                /* The I/O was aborted. */
                                 spin_unlock_irqrestore(&task->task_state_lock,
                                                        flags);
 
                                 isci_task_refuse(ihost, task,
                                                  SAS_TASK_UNDELIVERED,
                                                  SAM_STAT_TASK_ABORTED);
-
-                                /* The I/O was aborted. */
-
+                                isci_host_can_dequeue(ihost, 1);
                         } else {
                                 task->task_state_flags |= SAS_TASK_AT_INITIATOR;
                                 spin_unlock_irqrestore(&task->task_state_lock, flags);
@@ -323,11 +299,11 @@ int isci_task_execute_tmf(struct isci_host *ihost,
         /* sanity check, return TMF_RESP_FUNC_FAILED
          * if the device is not there and ready.
          */
-        if (!isci_device || isci_device->status != isci_ready_for_io) {
+        if (!isci_device || !test_bit(IDEV_IO_READY, &isci_device->flags)) {
                 dev_dbg(&ihost->pdev->dev,
-                        "%s: isci_device = %p not ready (%d)\n",
+                        "%s: isci_device = %p not ready (%#lx)\n",
                         __func__,
-                        isci_device, isci_device->status);
+                        isci_device, isci_device ? isci_device->flags : 0);
                 return TMF_RESP_FUNC_FAILED;
         } else
                 dev_dbg(&ihost->pdev->dev,