scsi: hisi_sas: check host frozen before calling "done" function

When the host is frozen in SCSI EH state, at any point after the LLDD
sets SAS_TASK_STATE_DONE for the sas_task task state, libsas may free
the task; see sas_scsi_find_task().

This puts the LLDD in a difficult position, in that once it sets
SAS_TASK_STATE_DONE for the task state it should not reference the
sas_task again. But the LLDD needs will check the sas_task indirectly in
calling task->task_done()->sas_scsi_task_done() or sas_ata_task_done()
(to check if the host is frozen state actually).

And the LLDD cannot set SAS_TASK_STATE_DONE for the task state after
task->task_done() is called (as the sas_task is free'd at this point).

This situation would seem to be a problem made by libsas.

To work around, check in the LLDD whether the host is in frozen state to
ensure it is ok to call task->task_done() function. If in the frozen
state, we rely on SCSI EH and libsas to free the sas_task directly.

We do not do this for the following IO types:

 - SMP - they are managed in libsas directly, outside SCSI EH
 - Any internally originated IO, for similar reason

Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
index 8ca0044e09be..6dda6eb50918 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
@@ -2380,18 +2380,21 @@ slot_complete_v2_hw(struct hisi_hba *hisi_hba, struct hisi_sas_slot *slot)
 	struct device *dev = hisi_hba->dev;
 	struct task_status_struct *ts;
 	struct domain_device *device;
+	struct sas_ha_struct *ha;
 	enum exec_status sts;
 	struct hisi_sas_complete_v2_hdr *complete_queue =
 			hisi_hba->complete_hdr[slot->cmplt_queue];
 	struct hisi_sas_complete_v2_hdr *complete_hdr =
 			&complete_queue[slot->cmplt_queue_slot];
 	unsigned long flags;
+	bool is_internal = slot->is_internal;
 
 	if (unlikely(!task || !task->lldd_task || !task->dev))
 		return -EINVAL;
 
 	ts = &task->task_status;
 	device = task->dev;
+	ha = device->port->ha;
 	sas_dev = device->lldd_dev;
 
 	spin_lock_irqsave(&task->task_state_lock, flags);
@@ -2523,6 +2526,17 @@ out:
 	task->task_state_flags |= SAS_TASK_STATE_DONE;
 	spin_unlock_irqrestore(&task->task_state_lock, flags);
 
+	if (!is_internal && (task->task_proto != SAS_PROTOCOL_SMP)) {
+		spin_lock_irqsave(&device->done_lock, flags);
+		if (test_bit(SAS_HA_FROZEN, &ha->state)) {
+			spin_unlock_irqrestore(&device->done_lock, flags);
+			dev_info(dev, "slot complete: task(%p) ignored\n ",
+				 task);
+			return sts;
+		}
+		spin_unlock_irqrestore(&device->done_lock, flags);
+	}
+
 	if (task->task_done)
 		task->task_done(task);