scsi: ufs: core: Fix device management cmd timeout flow

In the UFS error handling flow, the host will send a device management cmd
(NOP OUT) to the device for link recovery. If this cmd times out and
clearing the doorbell fails, ufshcd_wait_for_dev_cmd() will do nothing and
return. hba->dev_cmd.complete struct is not set to NULL.

When this happens, if cmd has been completed by device, then we will call
complete() in __ufshcd_transfer_req_compl(). Because the complete struct is
allocated on the stack, the following crash will occur:

  ipanic_die+0x24/0x38 [mrdump]
  die+0x344/0x748
  arm64_notify_die+0x44/0x104
  do_debug_exception+0x104/0x1e0
  el1_dbg+0x38/0x54
  el1_sync_handler+0x40/0x88
  el1_sync+0x8c/0x140
  queued_spin_lock_slowpath+0x2e4/0x3c0
  __ufshcd_transfer_req_compl+0x3b0/0x1164
  ufshcd_trc_handler+0x15c/0x308
  ufshcd_host_reset_and_restore+0x54/0x260
  ufshcd_reset_and_restore+0x28c/0x57c
  ufshcd_err_handler+0xeb8/0x1b6c
  process_one_work+0x288/0x964
  worker_thread+0x4bc/0xc7c
  kthread+0x15c/0x264
  ret_from_fork+0x10/0x30

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mason Zhang <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

Author: Mason Zhang

drivers/ufs/core/ufshcd.c

@@ -3109,6 +3109,22 @@ static int ufshcd_wait_for_dev_cmd(struct ufs_hba *hba,
 		} else {
 			dev_err(hba->dev, "%s: failed to clear tag %d\n",
 				__func__, lrbp->task_tag);
+
+			spin_lock_irqsave(&hba->outstanding_lock, flags);
+			pending = test_bit(lrbp->task_tag,
+					   &hba->outstanding_reqs);
+			if (pending)
+				hba->dev_cmd.complete = NULL;
+			spin_unlock_irqrestore(&hba->outstanding_lock, flags);
+
+			if (!pending) {
+				/*
+				 * The completion handler ran while we tried to
+				 * clear the command.
+				 */
+				time_left = 1;
+				goto retry;
+			}
 		}
 	}