scsi: ufs: Request sense data asynchronously

Clearing a unit attention synchronously from inside the UFS error handler
may trigger the following deadlock:

 - ufshcd_err_handler() calls ufshcd_err_handling_unprepare() and the
   latter function calls ufshcd_clear_ua_wluns().

 - ufshcd_clear_ua_wluns() submits a REQUEST SENSE command and that command
   activates the SCSI error handler.

 - The SCSI error handler calls ufshcd_host_reset_and_restore().

 - ufshcd_host_reset_and_restore() executes the following code:
   ufshcd_schedule_eh_work(hba); flush_work(&hba->eh_work);

This sequence results in a deadlock (circular wait). Fix this by requesting
sense data asynchronously.

Link: https://lore.kernel.org/r/20210722033439.26550-16-bvanassche@acm.org
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Stanley Chu <stanley.chu@mediatek.com>
Cc: Can Guo <cang@codeaurora.org>
Cc: Asutosh Das <asutoshd@codeaurora.org>
Cc: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index d52ba03ea9637389cddf39c10352d7513f7d8e1e..d4db56650bba68e3d0abb41e19a4efa0f2aa1417 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -7880,8 +7880,39 @@ out:
        return ret;
 }
 
+static void ufshcd_request_sense_done(struct request *rq, blk_status_t error)
+{
+       if (error != BLK_STS_OK)
+               pr_err("%s: REQUEST SENSE failed (%d)", __func__, error);
+       blk_put_request(rq);
+}
+
 static int
-ufshcd_send_request_sense(struct ufs_hba *hba, struct scsi_device *sdp);
+ufshcd_request_sense_async(struct ufs_hba *hba, struct scsi_device *sdev)
+{
+       /*
+        * From SPC-6: the REQUEST SENSE command with any allocation length
+        * clears the sense data.
+        */
+       static const u8 cmd[6] = {REQUEST_SENSE, 0, 0, 0, 0, 0};
+       struct scsi_request *rq;
+       struct request *req;
+
+       req = blk_get_request(sdev->request_queue, REQ_OP_DRV_IN, /*flags=*/0);
+       if (IS_ERR(req))
+               return PTR_ERR(req);
+
+       rq = scsi_req(req);
+       rq->cmd_len = ARRAY_SIZE(cmd);
+       memcpy(rq->cmd, cmd, rq->cmd_len);
+       rq->retries = 3;
+       req->timeout = 1 * HZ;
+       req->rq_flags |= RQF_PM | RQF_QUIET;
+
+       blk_execute_rq_nowait(/*bd_disk=*/NULL, req, /*at_head=*/true,
+                             ufshcd_request_sense_done);
+       return 0;
+}
 
 static int ufshcd_clear_ua_wlun(struct ufs_hba *hba, u8 wlun)
 {
@@ -7909,7 +7940,7 @@ static int ufshcd_clear_ua_wlun(struct ufs_hba *hba, u8 wlun)
        if (ret)
                goto out_err;
 
-       ret = ufshcd_send_request_sense(hba, sdp);
+       ret = ufshcd_request_sense_async(hba, sdp);
        scsi_device_put(sdp);
 out_err:
        if (ret)
@@ -8509,35 +8540,6 @@ static void ufshcd_hba_exit(struct ufs_hba *hba)
        }
 }
 
-static int
-ufshcd_send_request_sense(struct ufs_hba *hba, struct scsi_device *sdp)
-{
-       unsigned char cmd[6] = {REQUEST_SENSE,
-                               0,
-                               0,
-                               0,
-                               UFS_SENSE_SIZE,
-                               0};
-       char *buffer;
-       int ret;
-
-       buffer = kzalloc(UFS_SENSE_SIZE, GFP_KERNEL);
-       if (!buffer) {
-               ret = -ENOMEM;
-               goto out;
-       }
-
-       ret = scsi_execute(sdp, cmd, DMA_FROM_DEVICE, buffer,
-                       UFS_SENSE_SIZE, NULL, NULL,
-                       msecs_to_jiffies(1000), 3, 0, RQF_PM, NULL);
-       if (ret)
-               pr_err("%s: failed with err %d\n", __func__, ret);
-
-       kfree(buffer);
-out:
-       return ret;
-}
-
 /**
  * ufshcd_set_dev_pwr_mode - sends START STOP UNIT command to set device
  *                          power mode