[PATCH AUTOSEL 5.14 30/99] scsi: ufs: Request sense data asynchronously

Sasha Levin
2021-09-10T00:41:31Z

From: Bart Van Assche <bvanassche@acm.org>

[ Upstream commit ac1bc2ba060f9609972fb486073ebd9eab1ef3b6 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/ufs/ufshcd.c | 64 ++++++++++++++++++++-------------------
1 file changed, 33 insertions(+), 31 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 3350b0cff9ef..52731dffa624 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -7911,8 +7911,39 @@ static int ufshcd_add_lus(struct ufs_hba *hba)
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)
{
@@ -7940,7 +7971,7 @@ 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)
@@ -8535,35 +8566,6 @@ 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
--
2.30.2