[PATCH 0/2 v2] kill clearing UA in UFS driver

[PATCH 0/2 v2] kill clearing UA in UFS driver

[Jaegeuk Kim]

There are some issues reported and fixed when clearing UA on reset/PM flows.
Let's avoid any potential bugs entirely by letting user clear UA.

Bart Van Assche (1):
  scsi: ufs: Stop clearing unit attentions

Jaegeuk Kim (1):
  scsi: ufs: retry START_STOP on UNIT_ATTENTION

 drivers/scsi/ufs/ufshcd.c | 196 ++------------------------------------
 drivers/scsi/ufs/ufshcd.h |  14 ---
 2 files changed, 10 insertions(+), 200 deletions(-)

-- 
2.33.0.800.g4c38ced690-goog

[PATCH 1/2] scsi: ufs: retry START_STOP on UNIT_ATTENTION

[Jaegeuk Kim]

Commit 57d104c153d3 ("ufs: add UFS power management support") made the UFS
driver submit a REQUEST SENSE command before submitting a power management
command to a WLUN to clear the POWER ON unit attention. Instead of
submitting a REQUEST SENSE command before submitting a power management
command, retry the power management command until it succeeds.

This is the preparation to get rid of all UNIT ATTENTION code which should
be handled by users.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 drivers/scsi/ufs/ufshcd.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 9faf02cbb9ad..7ec72de826e5 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -8676,7 +8676,7 @@ static int ufshcd_set_dev_pwr_mode(struct ufs_hba *hba,
 	struct scsi_sense_hdr sshdr;
 	struct scsi_device *sdp;
 	unsigned long flags;
-	int ret;
+	int ret, retries;
 
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	sdp = hba->sdev_ufs_device;
@@ -8711,8 +8711,14 @@ static int ufshcd_set_dev_pwr_mode(struct ufs_hba *hba,
 	 * callbacks hence set the RQF_PM flag so that it doesn't resume the
 	 * already suspended childs.
 	 */
-	ret = scsi_execute(sdp, cmd, DMA_NONE, NULL, 0, NULL, &sshdr,
-			START_STOP_TIMEOUT, 0, 0, RQF_PM, NULL);
+	for (retries = 3; retries > 0; --retries) {
+		ret = scsi_execute(sdp, cmd, DMA_NONE, NULL, 0, NULL, &sshdr,
+				START_STOP_TIMEOUT, 0, 0, RQF_PM, NULL);
+		if (!scsi_status_is_check_condition(ret) ||
+				!scsi_sense_valid(&sshdr) ||
+				sshdr.sense_key != UNIT_ATTENTION)
+			break;
+	}
 	if (ret) {
 		sdev_printk(KERN_WARNING, sdp,
 			    "START_STOP failed for power mode: %d, result %x\n",
-- 
2.33.0.800.g4c38ced690-goog

[PATCH 2/2] scsi: ufs: Stop clearing unit attentions

[Jaegeuk Kim]

From: Bart Van Assche <bvanassche@google.com>

Commit aa53f580e67b ("scsi: ufs: Minor adjustments to error handling")
introduced a ufshcd_clear_ua_wluns() call in
ufshcd_err_handling_unprepare(). As explained in detail by Adrian Hunter,
this can trigger a deadlock. Avoid that deadlock by removing the code that
clears the unit attention. This is safe because the only software that
relies on clearing unit attentions is the Android Trusty software and
because support for handling unit attentions has been added in the Trusty software.

See also https://lore.kernel.org/linux-scsi/20210930124224.114031-2-adrian.hunter@intel.com/

Note that, should apply "scsi: ufs: retry START_STOP on UNIT_ATTENTION" before
this patch, since this patch gives UNIT ATTENTION to scsi_execute(START_STOP).

Cc: Adrian Hunter <adrian.hunter@intel.com>
Fixes: aa53f580e67b ("scsi: ufs: Minor adjustments to error handling")
Signed-off-by: Bart Van Assche <bvanassche@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 drivers/scsi/ufs/ufshcd.c | 184 +-------------------------------------
 drivers/scsi/ufs/ufshcd.h |  14 ---
 2 files changed, 1 insertion(+), 197 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 7ec72de826e5..0743f54e55f9 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -224,7 +224,6 @@ static int ufshcd_reset_and_restore(struct ufs_hba *hba);
 static int ufshcd_eh_host_reset_handler(struct scsi_cmnd *cmd);
 static int ufshcd_clear_tm_cmd(struct ufs_hba *hba, int tag);
 static void ufshcd_hba_exit(struct ufs_hba *hba);
-static int ufshcd_clear_ua_wluns(struct ufs_hba *hba);
 static int ufshcd_probe_hba(struct ufs_hba *hba, bool async);
 static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on);
 static inline void ufshcd_add_delay_before_dme_cmd(struct ufs_hba *hba);
@@ -4108,8 +4107,6 @@ int ufshcd_link_recovery(struct ufs_hba *hba)
 	if (ret)
 		dev_err(hba->dev, "%s: link recovery failed, err %d",
 			__func__, ret);
-	else
-		ufshcd_clear_ua_wluns(hba);
 
 	return ret;
 }
@@ -5995,7 +5992,6 @@ static void ufshcd_err_handling_unprepare(struct ufs_hba *hba)
 	ufshcd_release(hba);
 	if (ufshcd_is_clkscaling_supported(hba))
 		ufshcd_clk_scaling_suspend(hba, false);
-	ufshcd_clear_ua_wluns(hba);
 	ufshcd_rpm_put(hba);
 }
 
@@ -7953,8 +7949,6 @@ static int ufshcd_add_lus(struct ufs_hba *hba)
 	if (ret)
 		goto out;
 
-	ufshcd_clear_ua_wluns(hba);
-
 	/* Initialize devfreq after UFS device is detected */
 	if (ufshcd_is_clkscaling_supported(hba)) {
 		memcpy(&hba->clk_scaling.saved_pwr_info.info,
@@ -7980,116 +7974,6 @@ 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)\n", __func__, error);
-	kfree(rq->end_io_data);
-	blk_put_request(rq);
-}
-
-static int
-ufshcd_request_sense_async(struct ufs_hba *hba, struct scsi_device *sdev)
-{
-	/*
-	 * Some UFS devices clear unit attention condition only if the sense
-	 * size used (UFS_SENSE_SIZE in this case) is non-zero.
-	 */
-	static const u8 cmd[6] = {REQUEST_SENSE, 0, 0, 0, UFS_SENSE_SIZE, 0};
-	struct scsi_request *rq;
-	struct request *req;
-	char *buffer;
-	int ret;
-
-	buffer = kzalloc(UFS_SENSE_SIZE, GFP_KERNEL);
-	if (!buffer)
-		return -ENOMEM;
-
-	req = blk_get_request(sdev->request_queue, REQ_OP_DRV_IN,
-			      /*flags=*/BLK_MQ_REQ_PM);
-	if (IS_ERR(req)) {
-		ret = PTR_ERR(req);
-		goto out_free;
-	}
-
-	ret = blk_rq_map_kern(sdev->request_queue, req,
-			      buffer, UFS_SENSE_SIZE, GFP_NOIO);
-	if (ret)
-		goto out_put;
-
-	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;
-	req->end_io_data = buffer;
-
-	blk_execute_rq_nowait(/*bd_disk=*/NULL, req, /*at_head=*/true,
-			      ufshcd_request_sense_done);
-	return 0;
-
-out_put:
-	blk_put_request(req);
-out_free:
-	kfree(buffer);
-	return ret;
-}
-
-static int ufshcd_clear_ua_wlun(struct ufs_hba *hba, u8 wlun)
-{
-	struct scsi_device *sdp;
-	unsigned long flags;
-	int ret = 0;
-
-	spin_lock_irqsave(hba->host->host_lock, flags);
-	if (wlun == UFS_UPIU_UFS_DEVICE_WLUN)
-		sdp = hba->sdev_ufs_device;
-	else if (wlun == UFS_UPIU_RPMB_WLUN)
-		sdp = hba->sdev_rpmb;
-	else
-		BUG();
-	if (sdp) {
-		ret = scsi_device_get(sdp);
-		if (!ret && !scsi_device_online(sdp)) {
-			ret = -ENODEV;
-			scsi_device_put(sdp);
-		}
-	} else {
-		ret = -ENODEV;
-	}
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
-	if (ret)
-		goto out_err;
-
-	ret = ufshcd_request_sense_async(hba, sdp);
-	scsi_device_put(sdp);
-out_err:
-	if (ret)
-		dev_err(hba->dev, "%s: UAC clear LU=%x ret = %d\n",
-				__func__, wlun, ret);
-	return ret;
-}
-
-static int ufshcd_clear_ua_wluns(struct ufs_hba *hba)
-{
-	int ret = 0;
-
-	if (!hba->wlun_dev_clr_ua)
-		goto out;
-
-	ret = ufshcd_clear_ua_wlun(hba, UFS_UPIU_UFS_DEVICE_WLUN);
-	if (!ret)
-		ret = ufshcd_clear_ua_wlun(hba, UFS_UPIU_RPMB_WLUN);
-	if (!ret)
-		hba->wlun_dev_clr_ua = false;
-out:
-	if (ret)
-		dev_err(hba->dev, "%s: Failed to clear UAC WLUNS ret = %d\n",
-				__func__, ret);
-	return ret;
-}
-
 /**
  * ufshcd_probe_hba - probe hba to detect device and initialize it
  * @hba: per-adapter instance
@@ -8140,8 +8024,6 @@ static int ufshcd_probe_hba(struct ufs_hba *hba, bool init_dev_params)
 	/* UFS device is also active now */
 	ufshcd_set_ufs_dev_active(hba);
 	ufshcd_force_reset_auto_bkops(hba);
-	hba->wlun_dev_clr_ua = true;
-	hba->wlun_rpmb_clr_ua = true;
 
 	/* Gear up to HS gear if supported */
 	if (hba->max_pwr_info.is_valid) {
@@ -8701,8 +8583,6 @@ static int ufshcd_set_dev_pwr_mode(struct ufs_hba *hba,
 	 * handling context.
 	 */
 	hba->host->eh_noresume = 1;
-	if (hba->wlun_dev_clr_ua)
-		ufshcd_clear_ua_wlun(hba, UFS_UPIU_UFS_DEVICE_WLUN);
 
 	cmd[4] = pwr_mode << 4;
 
@@ -9768,10 +9648,6 @@ void ufshcd_resume_complete(struct device *dev)
 		ufshcd_rpm_put(hba);
 		hba->complete_put = false;
 	}
-	if (hba->rpmb_complete_put) {
-		ufshcd_rpmb_rpm_put(hba);
-		hba->rpmb_complete_put = false;
-	}
 }
 EXPORT_SYMBOL_GPL(ufshcd_resume_complete);
 
@@ -9794,10 +9670,6 @@ int ufshcd_suspend_prepare(struct device *dev)
 		}
 		hba->complete_put = true;
 	}
-	if (hba->sdev_rpmb) {
-		ufshcd_rpmb_rpm_get_sync(hba);
-		hba->rpmb_complete_put = true;
-	}
 	return 0;
 }
 EXPORT_SYMBOL_GPL(ufshcd_suspend_prepare);
@@ -9866,49 +9738,6 @@ static struct scsi_driver ufs_dev_wlun_template = {
 	},
 };
 
-static int ufshcd_rpmb_probe(struct device *dev)
-{
-	return is_rpmb_wlun(to_scsi_device(dev)) ? 0 : -ENODEV;
-}
-
-static inline int ufshcd_clear_rpmb_uac(struct ufs_hba *hba)
-{
-	int ret = 0;
-
-	if (!hba->wlun_rpmb_clr_ua)
-		return 0;
-	ret = ufshcd_clear_ua_wlun(hba, UFS_UPIU_RPMB_WLUN);
-	if (!ret)
-		hba->wlun_rpmb_clr_ua = 0;
-	return ret;
-}
-
-#ifdef CONFIG_PM
-static int ufshcd_rpmb_resume(struct device *dev)
-{
-	struct ufs_hba *hba = wlun_dev_to_hba(dev);
-
-	if (hba->sdev_rpmb)
-		ufshcd_clear_rpmb_uac(hba);
-	return 0;
-}
-#endif
-
-static const struct dev_pm_ops ufs_rpmb_pm_ops = {
-	SET_RUNTIME_PM_OPS(NULL, ufshcd_rpmb_resume, NULL)
-	SET_SYSTEM_SLEEP_PM_OPS(NULL, ufshcd_rpmb_resume)
-};
-
-/* ufs_rpmb_wlun_template - Describes UFS RPMB WLUN. Used only to send UAC. */
-static struct scsi_driver ufs_rpmb_wlun_template = {
-	.gendrv = {
-		.name = "ufs_rpmb_wlun",
-		.owner = THIS_MODULE,
-		.probe = ufshcd_rpmb_probe,
-		.pm = &ufs_rpmb_pm_ops,
-	},
-};
-
 static int __init ufshcd_core_init(void)
 {
 	int ret;
@@ -9917,24 +9746,13 @@ static int __init ufshcd_core_init(void)
 
 	ret = scsi_register_driver(&ufs_dev_wlun_template.gendrv);
 	if (ret)
-		goto debugfs_exit;
-
-	ret = scsi_register_driver(&ufs_rpmb_wlun_template.gendrv);
-	if (ret)
-		goto unregister;
-
-	return ret;
-unregister:
-	scsi_unregister_driver(&ufs_dev_wlun_template.gendrv);
-debugfs_exit:
-	ufs_debugfs_exit();
+		ufs_debugfs_exit();
 	return ret;
 }
 
 static void __exit ufshcd_core_exit(void)
 {
 	ufs_debugfs_exit();
-	scsi_unregister_driver(&ufs_rpmb_wlun_template.gendrv);
 	scsi_unregister_driver(&ufs_dev_wlun_template.gendrv);
 }
 
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index ed960d206260..782bbe6d5a52 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -875,9 +875,6 @@ struct ufs_hba {
 	struct ufs_vreg_info vreg_info;
 	struct list_head clk_list_head;
 
-	bool wlun_dev_clr_ua;
-	bool wlun_rpmb_clr_ua;
-
 	/* Number of requests aborts */
 	int req_abort_count;
 
@@ -924,7 +921,6 @@ struct ufs_hba {
 #endif
 	u32 luns_avail;
 	bool complete_put;
-	bool rpmb_complete_put;
 };
 
 /* Returns true if clocks can be gated. Otherwise false */
@@ -1408,14 +1404,4 @@ static inline int ufshcd_rpm_put(struct ufs_hba *hba)
 	return pm_runtime_put(&hba->sdev_ufs_device->sdev_gendev);
 }
 
-static inline int ufshcd_rpmb_rpm_get_sync(struct ufs_hba *hba)
-{
-	return pm_runtime_get_sync(&hba->sdev_rpmb->sdev_gendev);
-}
-
-static inline int ufshcd_rpmb_rpm_put(struct ufs_hba *hba)
-{
-	return pm_runtime_put(&hba->sdev_rpmb->sdev_gendev);
-}
-
 #endif /* End of Header */
-- 
2.33.0.800.g4c38ced690-goog

Re: [PATCH 0/2 v2] kill clearing UA in UFS driver

[Martin K. Petersen]

Jaegeuk,

> There are some issues reported and fixed when clearing UA on reset/PM
> flows.  Let's avoid any potential bugs entirely by letting user clear
> UA.

Applied to 5.16/scsi-staging, thanks!

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH 0/2 v2] kill clearing UA in UFS driver

[Martin K. Petersen]

On Fri, 1 Oct 2021 11:20:13 -0700, Jaegeuk Kim wrote:

> There are some issues reported and fixed when clearing UA on reset/PM flows.
> Let's avoid any potential bugs entirely by letting user clear UA.
> 
> Bart Van Assche (1):
>   scsi: ufs: Stop clearing unit attentions
> 
> Jaegeuk Kim (1):
>   scsi: ufs: retry START_STOP on UNIT_ATTENTION
> 
> [...]

Applied to 5.16/scsi-queue, thanks!

[1/2] scsi: ufs: retry START_STOP on UNIT_ATTENTION
      https://git.kernel.org/mkp/scsi/c/af21c3fd5b3e
[2/2] scsi: ufs: Stop clearing unit attentions
      https://git.kernel.org/mkp/scsi/c/edc0596cc04b

-- 
Martin K. Petersen	Oracle Linux Engineering