[PATCH V5 0/3] Minor fixes to UFS error handling

[PATCH V5 0/3] Minor fixes to UFS error handling

[Can Guo]

This series mainly fixes below two things which come along with UFS error
handling in some corner cases.
[1] Concurrency problems btw err_handler and paths like system suspend/resume/shutdown and async scan.
[2] Race condition btw UFS error recovery and task abort which happens to W-LU during suspend/resume/shutdown.

The 1st change is tested with error/fault injections to power mode change
operations during system PM operations and async scan. The 2nd change is
tested by mimicing SSU cmd timeout during suspend/resume/shutdown. The 3rd
one is just a minor change to a check condition in IRQ handler such that
the driver can dump host regs when AH8 error happens.

Change since v4:
- Fixed a typo found by Stanley.

Change since v3:
- Slightly updated some commit msg lines, no code changes.

Change since v2:
- Added one more minor change into this series.

Change since v1:
- Removed Change-Id from commit msg


Can Guo (3):
  scsi: ufs: Serialize eh_work with system PM events and async scan
  scsi: ufs: Fix a race condition between ufshcd_abort and eh_work
  scsi: ufs: Print host regs in IRQ handler when AH8 error happens

 drivers/scsi/ufs/ufshcd.c | 122 ++++++++++++++++++++++++++++++++--------------
 drivers/scsi/ufs/ufshcd.h |   3 ++
 2 files changed, 88 insertions(+), 37 deletions(-)

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

[PATCH V5 1/3] scsi: ufs: Serialize eh_work with system PM events and async scan

[Can Guo]

Serialize eh_work with system PM events and async scan to make sure eh_work
does not run in parallel with them.

Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Reviewed-by: Hongwu Su<hongwus@codeaurora.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 64 +++++++++++++++++++++++++++++------------------
 drivers/scsi/ufs/ufshcd.h |  1 +
 2 files changed, 41 insertions(+), 24 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 47c544d..f0bb3fc 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5597,7 +5597,9 @@ static inline void ufshcd_schedule_eh_work(struct ufs_hba *hba)
 static void ufshcd_err_handling_prepare(struct ufs_hba *hba)
 {
 	pm_runtime_get_sync(hba->dev);
-	if (pm_runtime_suspended(hba->dev)) {
+	if (pm_runtime_status_suspended(hba->dev) || hba->is_sys_suspended) {
+		enum ufs_pm_op pm_op;
+
 		/*
 		 * Don't assume anything of pm_runtime_get_sync(), if
 		 * resume fails, irq and clocks can be OFF, and powers
@@ -5612,7 +5614,8 @@ static void ufshcd_err_handling_prepare(struct ufs_hba *hba)
 		if (!ufshcd_is_clkgating_allowed(hba))
 			ufshcd_setup_clocks(hba, true);
 		ufshcd_release(hba);
-		ufshcd_vops_resume(hba, UFS_RUNTIME_PM);
+		pm_op = hba->is_sys_suspended ? UFS_SYSTEM_PM : UFS_RUNTIME_PM;
+		ufshcd_vops_resume(hba, pm_op);
 	} else {
 		ufshcd_hold(hba, false);
 		if (hba->clk_scaling.is_allowed) {
@@ -5633,7 +5636,7 @@ static void ufshcd_err_handling_unprepare(struct ufs_hba *hba)
 
 static inline bool ufshcd_err_handling_should_stop(struct ufs_hba *hba)
 {
-	return (hba->ufshcd_state == UFSHCD_STATE_ERROR ||
+	return (!hba->is_powered || hba->ufshcd_state == UFSHCD_STATE_ERROR ||
 		(!(hba->saved_err || hba->saved_uic_err || hba->force_reset ||
 			ufshcd_is_link_broken(hba))));
 }
@@ -5646,6 +5649,7 @@ static void ufshcd_recover_pm_error(struct ufs_hba *hba)
 	struct request_queue *q;
 	int ret;
 
+	hba->is_sys_suspended = false;
 	/*
 	 * Set RPM status of hba device to RPM_ACTIVE,
 	 * this also clears its runtime error.
@@ -5704,11 +5708,13 @@ static void ufshcd_err_handler(struct work_struct *work)
 
 	hba = container_of(work, struct ufs_hba, eh_work);
 
+	down(&hba->eh_sem);
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	if (ufshcd_err_handling_should_stop(hba)) {
 		if (hba->ufshcd_state != UFSHCD_STATE_ERROR)
 			hba->ufshcd_state = UFSHCD_STATE_OPERATIONAL;
 		spin_unlock_irqrestore(hba->host->host_lock, flags);
+		up(&hba->eh_sem);
 		return;
 	}
 	ufshcd_set_eh_in_progress(hba);
@@ -5716,20 +5722,18 @@ static void ufshcd_err_handler(struct work_struct *work)
 	ufshcd_err_handling_prepare(hba);
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	ufshcd_scsi_block_requests(hba);
-	/*
-	 * A full reset and restore might have happened after preparation
-	 * is finished, double check whether we should stop.
-	 */
-	if (ufshcd_err_handling_should_stop(hba)) {
-		if (hba->ufshcd_state != UFSHCD_STATE_ERROR)
-			hba->ufshcd_state = UFSHCD_STATE_OPERATIONAL;
-		goto out;
-	}
 	hba->ufshcd_state = UFSHCD_STATE_RESET;
 
 	/* Complete requests that have door-bell cleared by h/w */
 	ufshcd_complete_requests(hba);
 
+	/*
+	 * A full reset and restore might have happened after preparation
+	 * is finished, double check whether we should stop.
+	 */
+	if (ufshcd_err_handling_should_stop(hba))
+		goto skip_err_handling;
+
 	if (hba->dev_quirks & UFS_DEVICE_QUIRK_RECOVERY_FROM_DL_NAC_ERRORS) {
 		bool ret;
 
@@ -5737,17 +5741,10 @@ static void ufshcd_err_handler(struct work_struct *work)
 		/* release the lock as ufshcd_quirk_dl_nac_errors() may sleep */
 		ret = ufshcd_quirk_dl_nac_errors(hba);
 		spin_lock_irqsave(hba->host->host_lock, flags);
-		if (!ret && !hba->force_reset && ufshcd_is_link_active(hba))
+		if (!ret && ufshcd_err_handling_should_stop(hba))
 			goto skip_err_handling;
 	}
 
-	if (hba->force_reset || ufshcd_is_link_broken(hba) ||
-	    ufshcd_is_saved_err_fatal(hba) ||
-	    ((hba->saved_err & UIC_ERROR) &&
-	     (hba->saved_uic_err & (UFSHCD_UIC_DL_NAC_RECEIVED_ERROR |
-				    UFSHCD_UIC_DL_TCx_REPLAY_ERROR))))
-		needs_reset = true;
-
 	if ((hba->saved_err & (INT_FATAL_ERRORS | UFSHCD_UIC_HIBERN8_MASK)) ||
 	    (hba->saved_uic_err &&
 	     (hba->saved_uic_err != UFSHCD_UIC_PA_GENERIC_ERROR))) {
@@ -5767,8 +5764,14 @@ static void ufshcd_err_handler(struct work_struct *work)
 	 * transfers forcefully because they will get cleared during
 	 * host reset and restore
 	 */
-	if (needs_reset)
+	if (hba->force_reset || ufshcd_is_link_broken(hba) ||
+	    ufshcd_is_saved_err_fatal(hba) ||
+	    ((hba->saved_err & UIC_ERROR) &&
+	     (hba->saved_uic_err & (UFSHCD_UIC_DL_NAC_RECEIVED_ERROR |
+				    UFSHCD_UIC_DL_TCx_REPLAY_ERROR)))) {
+		needs_reset = true;
 		goto do_reset;
+	}
 
 	/*
 	 * If LINERESET was caught, UFS might have been put to PWM mode,
@@ -5876,12 +5879,11 @@ static void ufshcd_err_handler(struct work_struct *work)
 			dev_err_ratelimited(hba->dev, "%s: exit: saved_err 0x%x saved_uic_err 0x%x",
 			    __func__, hba->saved_err, hba->saved_uic_err);
 	}
-
-out:
 	ufshcd_clear_eh_in_progress(hba);
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 	ufshcd_scsi_unblock_requests(hba);
 	ufshcd_err_handling_unprepare(hba);
+	up(&hba->eh_sem);
 }
 
 /**
@@ -6856,6 +6858,7 @@ static int ufshcd_reset_and_restore(struct ufs_hba *hba)
 	 */
 	scsi_report_bus_reset(hba->host, 0);
 	if (err) {
+		hba->ufshcd_state = UFSHCD_STATE_ERROR;
 		hba->saved_err |= saved_err;
 		hba->saved_uic_err |= saved_uic_err;
 	}
@@ -7704,8 +7707,10 @@ static void ufshcd_async_scan(void *data, async_cookie_t cookie)
 	struct ufs_hba *hba = (struct ufs_hba *)data;
 	int ret;
 
+	down(&hba->eh_sem);
 	/* Initialize hba, detect and initialize UFS device */
 	ret = ufshcd_probe_hba(hba, true);
+	up(&hba->eh_sem);
 	if (ret)
 		goto out;
 
@@ -8718,6 +8723,7 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
 	int ret = 0;
 	ktime_t start = ktime_get();
 
+	down(&hba->eh_sem);
 	if (!hba || !hba->is_powered)
 		return 0;
 
@@ -8748,6 +8754,8 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
 		hba->curr_dev_pwr_mode, hba->uic_link_state);
 	if (!ret)
 		hba->is_sys_suspended = true;
+	else
+		up(&hba->eh_sem);
 	return ret;
 }
 EXPORT_SYMBOL(ufshcd_system_suspend);
@@ -8764,8 +8772,10 @@ int ufshcd_system_resume(struct ufs_hba *hba)
 	int ret = 0;
 	ktime_t start = ktime_get();
 
-	if (!hba)
+	if (!hba) {
+		up(&hba->eh_sem);
 		return -EINVAL;
+	}
 
 	if (!hba->is_powered || pm_runtime_suspended(hba->dev))
 		/*
@@ -8781,6 +8791,7 @@ int ufshcd_system_resume(struct ufs_hba *hba)
 		hba->curr_dev_pwr_mode, hba->uic_link_state);
 	if (!ret)
 		hba->is_sys_suspended = false;
+	up(&hba->eh_sem);
 	return ret;
 }
 EXPORT_SYMBOL(ufshcd_system_resume);
@@ -8872,6 +8883,7 @@ int ufshcd_shutdown(struct ufs_hba *hba)
 {
 	int ret = 0;
 
+	down(&hba->eh_sem);
 	if (!hba->is_powered)
 		goto out;
 
@@ -8888,6 +8900,8 @@ int ufshcd_shutdown(struct ufs_hba *hba)
 out:
 	if (ret)
 		dev_err(hba->dev, "%s failed, err %d\n", __func__, ret);
+	hba->is_powered = false;
+	up(&hba->eh_sem);
 	/* allow force shutdown even in case of errors */
 	return 0;
 }
@@ -9082,6 +9096,8 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 	INIT_WORK(&hba->eh_work, ufshcd_err_handler);
 	INIT_WORK(&hba->eeh_work, ufshcd_exception_event_handler);
 
+	sema_init(&hba->eh_sem, 1);
+
 	/* Initialize UIC command mutex */
 	mutex_init(&hba->uic_cmd_mutex);
 
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 47eb143..1e680bf 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -728,6 +728,7 @@ struct ufs_hba {
 	u32 intr_mask;
 	u16 ee_ctrl_mask;
 	bool is_powered;
+	struct semaphore eh_sem;
 
 	/* Work Queues */
 	struct workqueue_struct *eh_wq;
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

[PATCH V5 2/3] scsi: ufs: Fix a race condition between ufshcd_abort and eh_work

[Can Guo]

In current task abort routine, if task abort happens to the device W-LU,
the code directly jumps to ufshcd_eh_host_reset_handler() to perform a
full reset and restore then returns FAIL or SUCCESS. Commands sent to the
device W-LU are most likely the SSU cmds sent during UFS PM operations. If
such SSU cmd enters task abort routine, when ufshcd_eh_host_reset_handler()
flushes eh_work, it will get stuck there since err_handler is serialized
with PM operations.

In order to unblock above call path, we merely clean up the lrb taken by
this cmd, queue the eh_work and return SUCCESS. Once the cmd is aborted,
the PM operation which sends out the cmd just errors out, then err_handler
shall be able to proceed with the full reset and restore.

In this scenario, the cmd is aborted even before it is actually cleared by
HW, set the lrb->in_use flag to prevent subsequent cmds, including SCSI
cmds and dev cmds, from taking the lrb released from abort. The flag shall
evetually be cleared in __ufshcd_transfer_req_compl() invoked by the full
reset and restore from err_handler.

Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 55 ++++++++++++++++++++++++++++++++++++-----------
 drivers/scsi/ufs/ufshcd.h |  2 ++
 2 files changed, 45 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index f0bb3fc..fa90e15 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -2539,6 +2539,14 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 		(hba->clk_gating.state != CLKS_ON));
 
 	lrbp = &hba->lrb[tag];
+	if (unlikely(lrbp->in_use)) {
+		if (hba->pm_op_in_progress)
+			set_host_byte(cmd, DID_BAD_TARGET);
+		else
+			err = SCSI_MLQUEUE_HOST_BUSY;
+		ufshcd_release(hba);
+		goto out;
+	}
 
 	WARN_ON(lrbp->cmd);
 	lrbp->cmd = cmd;
@@ -2781,6 +2789,11 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba,
 
 	init_completion(&wait);
 	lrbp = &hba->lrb[tag];
+	if (unlikely(lrbp->in_use)) {
+		err = -EBUSY;
+		goto out;
+	}
+
 	WARN_ON(lrbp->cmd);
 	err = ufshcd_compose_dev_cmd(hba, lrbp, cmd_type, tag);
 	if (unlikely(err))
@@ -2797,6 +2810,7 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba,
 
 	err = ufshcd_wait_for_dev_cmd(hba, lrbp, timeout);
 
+out:
 	ufshcd_add_query_upiu_trace(hba, tag,
 			err ? "query_complete_err" : "query_complete");
 
@@ -4932,6 +4946,7 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba,
 
 	for_each_set_bit(index, &completed_reqs, hba->nutrs) {
 		lrbp = &hba->lrb[index];
+		lrbp->in_use = false;
 		lrbp->compl_time_stamp = ktime_get();
 		cmd = lrbp->cmd;
 		if (cmd) {
@@ -6374,8 +6389,12 @@ static int ufshcd_issue_devman_upiu_cmd(struct ufs_hba *hba,
 
 	init_completion(&wait);
 	lrbp = &hba->lrb[tag];
-	WARN_ON(lrbp->cmd);
+	if (unlikely(lrbp->in_use)) {
+		err = -EBUSY;
+		goto out;
+	}
 
+	WARN_ON(lrbp->cmd);
 	lrbp->cmd = NULL;
 	lrbp->sense_bufflen = 0;
 	lrbp->sense_buffer = NULL;
@@ -6447,6 +6466,7 @@ static int ufshcd_issue_devman_upiu_cmd(struct ufs_hba *hba,
 		}
 	}
 
+out:
 	blk_put_request(req);
 out_unlock:
 	up_read(&hba->clk_scaling_lock);
@@ -6696,16 +6716,6 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
 		BUG();
 	}
 
-	/*
-	 * Task abort to the device W-LUN is illegal. When this command
-	 * will fail, due to spec violation, scsi err handling next step
-	 * will be to send LU reset which, again, is a spec violation.
-	 * To avoid these unnecessary/illegal step we skip to the last error
-	 * handling stage: reset and restore.
-	 */
-	if (lrbp->lun == UFS_UPIU_UFS_DEVICE_WLUN)
-		return ufshcd_eh_host_reset_handler(cmd);
-
 	ufshcd_hold(hba, false);
 	reg = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
 	/* If command is already aborted/completed, return SUCCESS */
@@ -6726,7 +6736,7 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
 	 * to reduce repeated printouts. For other aborted requests only print
 	 * basic details.
 	 */
-	scsi_print_command(hba->lrb[tag].cmd);
+	scsi_print_command(cmd);
 	if (!hba->req_abort_count) {
 		ufshcd_update_reg_hist(&hba->ufs_stats.task_abort, 0);
 		ufshcd_print_host_regs(hba);
@@ -6745,6 +6755,27 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
 		goto cleanup;
 	}
 
+	/*
+	 * Task abort to the device W-LUN is illegal. When this command
+	 * will fail, due to spec violation, scsi err handling next step
+	 * will be to send LU reset which, again, is a spec violation.
+	 * To avoid these unnecessary/illegal steps, first we clean up
+	 * the lrb taken by this cmd and mark the lrb as in_use, then
+	 * queue the eh_work and bail.
+	 */
+	if (lrbp->lun == UFS_UPIU_UFS_DEVICE_WLUN) {
+		spin_lock_irqsave(host->host_lock, flags);
+		if (lrbp->cmd) {
+			__ufshcd_transfer_req_compl(hba, (1UL << tag));
+			__set_bit(tag, &hba->outstanding_reqs);
+			lrbp->in_use = true;
+			hba->force_reset = true;
+			ufshcd_schedule_eh_work(hba);
+		}
+		spin_unlock_irqrestore(host->host_lock, flags);
+		goto out;
+	}
+
 	/* Skip task abort in case previous aborts failed and report failure */
 	if (lrbp->req_abort_skip)
 		err = -EIO;
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 1e680bf..66e5338 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -163,6 +163,7 @@ struct ufs_pm_lvl_states {
  * @crypto_key_slot: the key slot to use for inline crypto (-1 if none)
  * @data_unit_num: the data unit number for the first block for inline crypto
  * @req_abort_skip: skip request abort task flag
+ * @in_use: indicates that this lrb is still in use
  */
 struct ufshcd_lrb {
 	struct utp_transfer_req_desc *utr_descriptor_ptr;
@@ -192,6 +193,7 @@ struct ufshcd_lrb {
 #endif
 
 	bool req_abort_skip;
+	bool in_use;
 };
 
 /**
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

[PATCH V5 3/3] scsi: ufs: Print host regs in IRQ handler when AH8 error happens

[Can Guo]

When AH8 error happens, all the regs and states are dumped in err handler.
Sometime we need to look into host regs right after AH8 error happens,
which is before leaving the IRQ handler.

Reviewed-by: Bao D. Nguyen <nguyenb@codeaurora.org>
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Reviewed-by: Hongwu Su<hongwus@codeaurora.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index fa90e15..94405e4 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6057,7 +6057,8 @@ static irqreturn_t ufshcd_check_errors(struct ufs_hba *hba)
 		hba->saved_uic_err |= hba->uic_error;
 
 		/* dump controller state before resetting */
-		if ((hba->saved_err & (INT_FATAL_ERRORS)) ||
+		if ((hba->saved_err &
+		     (INT_FATAL_ERRORS | UFSHCD_UIC_HIBERN8_MASK)) ||
 		    (hba->saved_uic_err &&
 		     (hba->saved_uic_err != UFSHCD_UIC_PA_GENERIC_ERROR))) {
 			dev_err(hba->dev, "%s: saved_err 0x%x saved_uic_err 0x%x\n",
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

Re: [PATCH V5 1/3] scsi: ufs: Serialize eh_work with system PM events and async scan

[Stanley Chu]

On Wed, 2020-12-02 at 00:24 -0800, Can Guo wrote:
> Serialize eh_work with system PM events and async scan to make sure eh_work
> does not run in parallel with them.
> 
> Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
> Reviewed-by: Hongwu Su<hongwus@codeaurora.org>
> Signed-off-by: Can Guo <cang@codeaurora.org>

Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>

Re: [PATCH V5 1/3] scsi: ufs: Serialize eh_work with system PM events and async scan

[nguyenb]

On 2020-12-02 00:24, Can Guo wrote:
> Serialize eh_work with system PM events and async scan to make sure 
> eh_work
> does not run in parallel with them.
> 
> Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
> Reviewed-by: Hongwu Su<hongwus@codeaurora.org>
> Signed-off-by: Can Guo <cang@codeaurora.org>
> ---
>  drivers/scsi/ufs/ufshcd.c | 64 
> +++++++++++++++++++++++++++++------------------
>  drivers/scsi/ufs/ufshcd.h |  1 +
>  2 files changed, 41 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 47c544d..f0bb3fc 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -5597,7 +5597,9 @@ static inline void
> ufshcd_schedule_eh_work(struct ufs_hba *hba)
>  static void ufshcd_err_handling_prepare(struct ufs_hba *hba)
>  {
>  	pm_runtime_get_sync(hba->dev);
> -	if (pm_runtime_suspended(hba->dev)) {
> +	if (pm_runtime_status_suspended(hba->dev) || hba->is_sys_suspended) {
> +		enum ufs_pm_op pm_op;
> +
>  		/*
>  		 * Don't assume anything of pm_runtime_get_sync(), if
>  		 * resume fails, irq and clocks can be OFF, and powers
> @@ -5612,7 +5614,8 @@ static void ufshcd_err_handling_prepare(struct
> ufs_hba *hba)
>  		if (!ufshcd_is_clkgating_allowed(hba))
>  			ufshcd_setup_clocks(hba, true);
>  		ufshcd_release(hba);
> -		ufshcd_vops_resume(hba, UFS_RUNTIME_PM);
> +		pm_op = hba->is_sys_suspended ? UFS_SYSTEM_PM : UFS_RUNTIME_PM;
> +		ufshcd_vops_resume(hba, pm_op);
>  	} else {
>  		ufshcd_hold(hba, false);
>  		if (hba->clk_scaling.is_allowed) {
> @@ -5633,7 +5636,7 @@ static void ufshcd_err_handling_unprepare(struct
> ufs_hba *hba)
> 
>  static inline bool ufshcd_err_handling_should_stop(struct ufs_hba 
> *hba)
>  {
> -	return (hba->ufshcd_state == UFSHCD_STATE_ERROR ||
> +	return (!hba->is_powered || hba->ufshcd_state == UFSHCD_STATE_ERROR 
> ||
>  		(!(hba->saved_err || hba->saved_uic_err || hba->force_reset ||
>  			ufshcd_is_link_broken(hba))));
>  }
> @@ -5646,6 +5649,7 @@ static void ufshcd_recover_pm_error(struct 
> ufs_hba *hba)
>  	struct request_queue *q;
>  	int ret;
> 
> +	hba->is_sys_suspended = false;
>  	/*
>  	 * Set RPM status of hba device to RPM_ACTIVE,
>  	 * this also clears its runtime error.
> @@ -5704,11 +5708,13 @@ static void ufshcd_err_handler(struct 
> work_struct *work)
> 
>  	hba = container_of(work, struct ufs_hba, eh_work);
> 
> +	down(&hba->eh_sem);
>  	spin_lock_irqsave(hba->host->host_lock, flags);
>  	if (ufshcd_err_handling_should_stop(hba)) {
>  		if (hba->ufshcd_state != UFSHCD_STATE_ERROR)
>  			hba->ufshcd_state = UFSHCD_STATE_OPERATIONAL;
>  		spin_unlock_irqrestore(hba->host->host_lock, flags);
> +		up(&hba->eh_sem);
>  		return;
>  	}
>  	ufshcd_set_eh_in_progress(hba);
> @@ -5716,20 +5722,18 @@ static void ufshcd_err_handler(struct 
> work_struct *work)
>  	ufshcd_err_handling_prepare(hba);
>  	spin_lock_irqsave(hba->host->host_lock, flags);
>  	ufshcd_scsi_block_requests(hba);
> -	/*
> -	 * A full reset and restore might have happened after preparation
> -	 * is finished, double check whether we should stop.
> -	 */
> -	if (ufshcd_err_handling_should_stop(hba)) {
> -		if (hba->ufshcd_state != UFSHCD_STATE_ERROR)
> -			hba->ufshcd_state = UFSHCD_STATE_OPERATIONAL;
> -		goto out;
> -	}
>  	hba->ufshcd_state = UFSHCD_STATE_RESET;
> 
>  	/* Complete requests that have door-bell cleared by h/w */
>  	ufshcd_complete_requests(hba);
> 
> +	/*
> +	 * A full reset and restore might have happened after preparation
> +	 * is finished, double check whether we should stop.
> +	 */
> +	if (ufshcd_err_handling_should_stop(hba))
> +		goto skip_err_handling;
> +
>  	if (hba->dev_quirks & UFS_DEVICE_QUIRK_RECOVERY_FROM_DL_NAC_ERRORS) {
>  		bool ret;
> 
> @@ -5737,17 +5741,10 @@ static void ufshcd_err_handler(struct 
> work_struct *work)
>  		/* release the lock as ufshcd_quirk_dl_nac_errors() may sleep */
>  		ret = ufshcd_quirk_dl_nac_errors(hba);
>  		spin_lock_irqsave(hba->host->host_lock, flags);
> -		if (!ret && !hba->force_reset && ufshcd_is_link_active(hba))
> +		if (!ret && ufshcd_err_handling_should_stop(hba))
>  			goto skip_err_handling;
>  	}
> 
> -	if (hba->force_reset || ufshcd_is_link_broken(hba) ||
> -	    ufshcd_is_saved_err_fatal(hba) ||
> -	    ((hba->saved_err & UIC_ERROR) &&
> -	     (hba->saved_uic_err & (UFSHCD_UIC_DL_NAC_RECEIVED_ERROR |
> -				    UFSHCD_UIC_DL_TCx_REPLAY_ERROR))))
> -		needs_reset = true;
> -
>  	if ((hba->saved_err & (INT_FATAL_ERRORS | UFSHCD_UIC_HIBERN8_MASK)) 
> ||
>  	    (hba->saved_uic_err &&
>  	     (hba->saved_uic_err != UFSHCD_UIC_PA_GENERIC_ERROR))) {
> @@ -5767,8 +5764,14 @@ static void ufshcd_err_handler(struct 
> work_struct *work)
>  	 * transfers forcefully because they will get cleared during
>  	 * host reset and restore
>  	 */
> -	if (needs_reset)
> +	if (hba->force_reset || ufshcd_is_link_broken(hba) ||
> +	    ufshcd_is_saved_err_fatal(hba) ||
> +	    ((hba->saved_err & UIC_ERROR) &&
> +	     (hba->saved_uic_err & (UFSHCD_UIC_DL_NAC_RECEIVED_ERROR |
> +				    UFSHCD_UIC_DL_TCx_REPLAY_ERROR)))) {
> +		needs_reset = true;
>  		goto do_reset;
> +	}
> 
>  	/*
>  	 * If LINERESET was caught, UFS might have been put to PWM mode,
> @@ -5876,12 +5879,11 @@ static void ufshcd_err_handler(struct 
> work_struct *work)
>  			dev_err_ratelimited(hba->dev, "%s: exit: saved_err 0x%x 
> saved_uic_err 0x%x",
>  			    __func__, hba->saved_err, hba->saved_uic_err);
>  	}
> -
> -out:
>  	ufshcd_clear_eh_in_progress(hba);
>  	spin_unlock_irqrestore(hba->host->host_lock, flags);
>  	ufshcd_scsi_unblock_requests(hba);
>  	ufshcd_err_handling_unprepare(hba);
> +	up(&hba->eh_sem);
>  }
> 
>  /**
> @@ -6856,6 +6858,7 @@ static int ufshcd_reset_and_restore(struct 
> ufs_hba *hba)
>  	 */
>  	scsi_report_bus_reset(hba->host, 0);
>  	if (err) {
> +		hba->ufshcd_state = UFSHCD_STATE_ERROR;
>  		hba->saved_err |= saved_err;
>  		hba->saved_uic_err |= saved_uic_err;
>  	}
> @@ -7704,8 +7707,10 @@ static void ufshcd_async_scan(void *data,
> async_cookie_t cookie)
>  	struct ufs_hba *hba = (struct ufs_hba *)data;
>  	int ret;
> 
> +	down(&hba->eh_sem);
>  	/* Initialize hba, detect and initialize UFS device */
>  	ret = ufshcd_probe_hba(hba, true);
> +	up(&hba->eh_sem);
>  	if (ret)
>  		goto out;
> 
> @@ -8718,6 +8723,7 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
>  	int ret = 0;
>  	ktime_t start = ktime_get();
> 
> +	down(&hba->eh_sem);
>  	if (!hba || !hba->is_powered)
>  		return 0;
> 
> @@ -8748,6 +8754,8 @@ int ufshcd_system_suspend(struct ufs_hba *hba)
>  		hba->curr_dev_pwr_mode, hba->uic_link_state);
>  	if (!ret)
>  		hba->is_sys_suspended = true;
> +	else
> +		up(&hba->eh_sem);
>  	return ret;
>  }
>  EXPORT_SYMBOL(ufshcd_system_suspend);
> @@ -8764,8 +8772,10 @@ int ufshcd_system_resume(struct ufs_hba *hba)
>  	int ret = 0;
>  	ktime_t start = ktime_get();
> 
> -	if (!hba)
> +	if (!hba) {
> +		up(&hba->eh_sem);
>  		return -EINVAL;
> +	}
> 
>  	if (!hba->is_powered || pm_runtime_suspended(hba->dev))
>  		/*
> @@ -8781,6 +8791,7 @@ int ufshcd_system_resume(struct ufs_hba *hba)
>  		hba->curr_dev_pwr_mode, hba->uic_link_state);
>  	if (!ret)
>  		hba->is_sys_suspended = false;
> +	up(&hba->eh_sem);
>  	return ret;
>  }
>  EXPORT_SYMBOL(ufshcd_system_resume);
> @@ -8872,6 +8883,7 @@ int ufshcd_shutdown(struct ufs_hba *hba)
>  {
>  	int ret = 0;
> 
> +	down(&hba->eh_sem);
>  	if (!hba->is_powered)
>  		goto out;
> 
> @@ -8888,6 +8900,8 @@ int ufshcd_shutdown(struct ufs_hba *hba)
>  out:
>  	if (ret)
>  		dev_err(hba->dev, "%s failed, err %d\n", __func__, ret);
> +	hba->is_powered = false;
> +	up(&hba->eh_sem);
>  	/* allow force shutdown even in case of errors */
>  	return 0;
>  }
> @@ -9082,6 +9096,8 @@ int ufshcd_init(struct ufs_hba *hba, void
> __iomem *mmio_base, unsigned int irq)
>  	INIT_WORK(&hba->eh_work, ufshcd_err_handler);
>  	INIT_WORK(&hba->eeh_work, ufshcd_exception_event_handler);
> 
> +	sema_init(&hba->eh_sem, 1);
> +
>  	/* Initialize UIC command mutex */
>  	mutex_init(&hba->uic_cmd_mutex);
> 
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index 47eb143..1e680bf 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -728,6 +728,7 @@ struct ufs_hba {
>  	u32 intr_mask;
>  	u16 ee_ctrl_mask;
>  	bool is_powered;
> +	struct semaphore eh_sem;
> 
>  	/* Work Queues */
>  	struct workqueue_struct *eh_wq;
Reviewed-by: Bao D. Nguyen <nguyenb@codeaurora.org>

Re: [PATCH V5 2/3] scsi: ufs: Fix a race condition between ufshcd_abort and eh_work

[Stanley Chu]

Hi Can,

On Wed, 2020-12-02 at 00:24 -0800, Can Guo wrote:
> In current task abort routine, if task abort happens to the device W-LU,
> the code directly jumps to ufshcd_eh_host_reset_handler() to perform a
> full reset and restore then returns FAIL or SUCCESS. Commands sent to the
> device W-LU are most likely the SSU cmds sent during UFS PM operations. If
> such SSU cmd enters task abort routine, when ufshcd_eh_host_reset_handler()
> flushes eh_work, it will get stuck there since err_handler is serialized
> with PM operations.
> 
> In order to unblock above call path, we merely clean up the lrb taken by
> this cmd, queue the eh_work and return SUCCESS. Once the cmd is aborted,
> the PM operation which sends out the cmd just errors out, then err_handler
> shall be able to proceed with the full reset and restore.
> 
> In this scenario, the cmd is aborted even before it is actually cleared by
> HW, set the lrb->in_use flag to prevent subsequent cmds, including SCSI
> cmds and dev cmds, from taking the lrb released from abort. The flag shall
> evetually be cleared in __ufshcd_transfer_req_compl() invoked by the full
> reset and restore from err_handler.
> 
> Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
> Signed-off-by: Can Guo <cang@codeaurora.org>
> ---
>  drivers/scsi/ufs/ufshcd.c | 55 ++++++++++++++++++++++++++++++++++++-----------
>  drivers/scsi/ufs/ufshcd.h |  2 ++
>  2 files changed, 45 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index f0bb3fc..fa90e15 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -2539,6 +2539,14 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
>  		(hba->clk_gating.state != CLKS_ON));
>  
>  	lrbp = &hba->lrb[tag];
> +	if (unlikely(lrbp->in_use)) {
> +		if (hba->pm_op_in_progress)
> +			set_host_byte(cmd, DID_BAD_TARGET);
> +		else
> +			err = SCSI_MLQUEUE_HOST_BUSY;
> +		ufshcd_release(hba);
> +		goto out;
> +	}
>  
>  	WARN_ON(lrbp->cmd);
>  	lrbp->cmd = cmd;
> @@ -2781,6 +2789,11 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba,
>  
>  	init_completion(&wait);
>  	lrbp = &hba->lrb[tag];
> +	if (unlikely(lrbp->in_use)) {
> +		err = -EBUSY;
> +		goto out;
> +	}
> +
>  	WARN_ON(lrbp->cmd);
>  	err = ufshcd_compose_dev_cmd(hba, lrbp, cmd_type, tag);
>  	if (unlikely(err))
> @@ -2797,6 +2810,7 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba,
>  
>  	err = ufshcd_wait_for_dev_cmd(hba, lrbp, timeout);
>  
> +out:
>  	ufshcd_add_query_upiu_trace(hba, tag,
>  			err ? "query_complete_err" : "query_complete");
>  
> @@ -4932,6 +4946,7 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba,
>  
>  	for_each_set_bit(index, &completed_reqs, hba->nutrs) {
>  		lrbp = &hba->lrb[index];
> +		lrbp->in_use = false;
>  		lrbp->compl_time_stamp = ktime_get();
>  		cmd = lrbp->cmd;
>  		if (cmd) {
> @@ -6374,8 +6389,12 @@ static int ufshcd_issue_devman_upiu_cmd(struct ufs_hba *hba,
>  
>  	init_completion(&wait);
>  	lrbp = &hba->lrb[tag];
> -	WARN_ON(lrbp->cmd);
> +	if (unlikely(lrbp->in_use)) {
> +		err = -EBUSY;
> +		goto out;
> +	}
>  
> +	WARN_ON(lrbp->cmd);
>  	lrbp->cmd = NULL;
>  	lrbp->sense_bufflen = 0;
>  	lrbp->sense_buffer = NULL;
> @@ -6447,6 +6466,7 @@ static int ufshcd_issue_devman_upiu_cmd(struct ufs_hba *hba,
>  		}
>  	}
>  
> +out:
>  	blk_put_request(req);
>  out_unlock:
>  	up_read(&hba->clk_scaling_lock);
> @@ -6696,16 +6716,6 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
>  		BUG();
>  	}
>  
> -	/*
> -	 * Task abort to the device W-LUN is illegal. When this command
> -	 * will fail, due to spec violation, scsi err handling next step
> -	 * will be to send LU reset which, again, is a spec violation.
> -	 * To avoid these unnecessary/illegal step we skip to the last error
> -	 * handling stage: reset and restore.
> -	 */
> -	if (lrbp->lun == UFS_UPIU_UFS_DEVICE_WLUN)
> -		return ufshcd_eh_host_reset_handler(cmd);
> -
>  	ufshcd_hold(hba, false);
>  	reg = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
>  	/* If command is already aborted/completed, return SUCCESS */
> @@ -6726,7 +6736,7 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
>  	 * to reduce repeated printouts. For other aborted requests only print
>  	 * basic details.
>  	 */
> -	scsi_print_command(hba->lrb[tag].cmd);
> +	scsi_print_command(cmd);
>  	if (!hba->req_abort_count) {
>  		ufshcd_update_reg_hist(&hba->ufs_stats.task_abort, 0);
>  		ufshcd_print_host_regs(hba);
> @@ -6745,6 +6755,27 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
>  		goto cleanup;
>  	}
>  
> +	/*
> +	 * Task abort to the device W-LUN is illegal. When this command
> +	 * will fail, due to spec violation, scsi err handling next step
> +	 * will be to send LU reset which, again, is a spec violation.
> +	 * To avoid these unnecessary/illegal steps, first we clean up
> +	 * the lrb taken by this cmd and mark the lrb as in_use, then
> +	 * queue the eh_work and bail.
> +	 */
> +	if (lrbp->lun == UFS_UPIU_UFS_DEVICE_WLUN) {
> +		spin_lock_irqsave(host->host_lock, flags);
> +		if (lrbp->cmd) {
> +			__ufshcd_transfer_req_compl(hba, (1UL << tag));

The timed out "tag" is cleared once here.

> +			__set_bit(tag, &hba->outstanding_reqs);
> +			lrbp->in_use = true;
> +			hba->force_reset = true;
> +			ufshcd_schedule_eh_work(hba);

The same "tag" would be cleared again in error handler with
__ufshcd_transfer_req_compl().

In __ufshcd_transfer_req_compl, hba->clk_scaling.active_reqs will be
decreased if clk-scaling is supported as below,

	if (ufshcd_is_clkscaling_supported(hba))
		hba->clk_scaling.active_reqs--;

Will be the hba->clk_scaling.active_reqs value become abnormal by this
flow?

Thanks,
Stanley Chu

> +		}
> +		spin_unlock_irqrestore(host->host_lock, flags);
> +		goto out;
> +	}
> +
>  	/* Skip task abort in case previous aborts failed and report failure */
>  	if (lrbp->req_abort_skip)
>  		err = -EIO;
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index 1e680bf..66e5338 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -163,6 +163,7 @@ struct ufs_pm_lvl_states {
>   * @crypto_key_slot: the key slot to use for inline crypto (-1 if none)
>   * @data_unit_num: the data unit number for the first block for inline crypto
>   * @req_abort_skip: skip request abort task flag
> + * @in_use: indicates that this lrb is still in use
>   */
>  struct ufshcd_lrb {
>  	struct utp_transfer_req_desc *utr_descriptor_ptr;
> @@ -192,6 +193,7 @@ struct ufshcd_lrb {
>  #endif
>  
>  	bool req_abort_skip;
> +	bool in_use;
>  };
>  
>  /**

Re: [PATCH V5 3/3] scsi: ufs: Print host regs in IRQ handler when AH8 error happens

[Stanley Chu]

On Wed, 2020-12-02 at 00:24 -0800, Can Guo wrote:
> When AH8 error happens, all the regs and states are dumped in err handler.
> Sometime we need to look into host regs right after AH8 error happens,
> which is before leaving the IRQ handler.
> 
> Reviewed-by: Bao D. Nguyen <nguyenb@codeaurora.org>
> Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
> Reviewed-by: Hongwu Su<hongwus@codeaurora.org>
> Signed-off-by: Can Guo <cang@codeaurora.org>

Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>

Re: [PATCH V5 2/3] scsi: ufs: Fix a race condition between ufshcd_abort and eh_work

[Can Guo]

On 2020-12-02 16:48, Stanley Chu wrote:
> Hi Can,
> 
> On Wed, 2020-12-02 at 00:24 -0800, Can Guo wrote:
>> In current task abort routine, if task abort happens to the device 
>> W-LU,
>> the code directly jumps to ufshcd_eh_host_reset_handler() to perform a
>> full reset and restore then returns FAIL or SUCCESS. Commands sent to 
>> the
>> device W-LU are most likely the SSU cmds sent during UFS PM 
>> operations. If
>> such SSU cmd enters task abort routine, when 
>> ufshcd_eh_host_reset_handler()
>> flushes eh_work, it will get stuck there since err_handler is 
>> serialized
>> with PM operations.
>> 
>> In order to unblock above call path, we merely clean up the lrb taken 
>> by
>> this cmd, queue the eh_work and return SUCCESS. Once the cmd is 
>> aborted,
>> the PM operation which sends out the cmd just errors out, then 
>> err_handler
>> shall be able to proceed with the full reset and restore.
>> 
>> In this scenario, the cmd is aborted even before it is actually 
>> cleared by
>> HW, set the lrb->in_use flag to prevent subsequent cmds, including 
>> SCSI
>> cmds and dev cmds, from taking the lrb released from abort. The flag 
>> shall
>> evetually be cleared in __ufshcd_transfer_req_compl() invoked by the 
>> full
>> reset and restore from err_handler.
>> 
>> Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> ---
>>  drivers/scsi/ufs/ufshcd.c | 55 
>> ++++++++++++++++++++++++++++++++++++-----------
>>  drivers/scsi/ufs/ufshcd.h |  2 ++
>>  2 files changed, 45 insertions(+), 12 deletions(-)
>> 
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index f0bb3fc..fa90e15 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -2539,6 +2539,14 @@ static int ufshcd_queuecommand(struct Scsi_Host 
>> *host, struct scsi_cmnd *cmd)
>>  		(hba->clk_gating.state != CLKS_ON));
>> 
>>  	lrbp = &hba->lrb[tag];
>> +	if (unlikely(lrbp->in_use)) {
>> +		if (hba->pm_op_in_progress)
>> +			set_host_byte(cmd, DID_BAD_TARGET);
>> +		else
>> +			err = SCSI_MLQUEUE_HOST_BUSY;
>> +		ufshcd_release(hba);
>> +		goto out;
>> +	}
>> 
>>  	WARN_ON(lrbp->cmd);
>>  	lrbp->cmd = cmd;
>> @@ -2781,6 +2789,11 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba 
>> *hba,
>> 
>>  	init_completion(&wait);
>>  	lrbp = &hba->lrb[tag];
>> +	if (unlikely(lrbp->in_use)) {
>> +		err = -EBUSY;
>> +		goto out;
>> +	}
>> +
>>  	WARN_ON(lrbp->cmd);
>>  	err = ufshcd_compose_dev_cmd(hba, lrbp, cmd_type, tag);
>>  	if (unlikely(err))
>> @@ -2797,6 +2810,7 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba 
>> *hba,
>> 
>>  	err = ufshcd_wait_for_dev_cmd(hba, lrbp, timeout);
>> 
>> +out:
>>  	ufshcd_add_query_upiu_trace(hba, tag,
>>  			err ? "query_complete_err" : "query_complete");
>> 
>> @@ -4932,6 +4946,7 @@ static void __ufshcd_transfer_req_compl(struct 
>> ufs_hba *hba,
>> 
>>  	for_each_set_bit(index, &completed_reqs, hba->nutrs) {
>>  		lrbp = &hba->lrb[index];
>> +		lrbp->in_use = false;
>>  		lrbp->compl_time_stamp = ktime_get();
>>  		cmd = lrbp->cmd;
>>  		if (cmd) {
>> @@ -6374,8 +6389,12 @@ static int ufshcd_issue_devman_upiu_cmd(struct 
>> ufs_hba *hba,
>> 
>>  	init_completion(&wait);
>>  	lrbp = &hba->lrb[tag];
>> -	WARN_ON(lrbp->cmd);
>> +	if (unlikely(lrbp->in_use)) {
>> +		err = -EBUSY;
>> +		goto out;
>> +	}
>> 
>> +	WARN_ON(lrbp->cmd);
>>  	lrbp->cmd = NULL;
>>  	lrbp->sense_bufflen = 0;
>>  	lrbp->sense_buffer = NULL;
>> @@ -6447,6 +6466,7 @@ static int ufshcd_issue_devman_upiu_cmd(struct 
>> ufs_hba *hba,
>>  		}
>>  	}
>> 
>> +out:
>>  	blk_put_request(req);
>>  out_unlock:
>>  	up_read(&hba->clk_scaling_lock);
>> @@ -6696,16 +6716,6 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
>>  		BUG();
>>  	}
>> 
>> -	/*
>> -	 * Task abort to the device W-LUN is illegal. When this command
>> -	 * will fail, due to spec violation, scsi err handling next step
>> -	 * will be to send LU reset which, again, is a spec violation.
>> -	 * To avoid these unnecessary/illegal step we skip to the last error
>> -	 * handling stage: reset and restore.
>> -	 */
>> -	if (lrbp->lun == UFS_UPIU_UFS_DEVICE_WLUN)
>> -		return ufshcd_eh_host_reset_handler(cmd);
>> -
>>  	ufshcd_hold(hba, false);
>>  	reg = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
>>  	/* If command is already aborted/completed, return SUCCESS */
>> @@ -6726,7 +6736,7 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
>>  	 * to reduce repeated printouts. For other aborted requests only 
>> print
>>  	 * basic details.
>>  	 */
>> -	scsi_print_command(hba->lrb[tag].cmd);
>> +	scsi_print_command(cmd);
>>  	if (!hba->req_abort_count) {
>>  		ufshcd_update_reg_hist(&hba->ufs_stats.task_abort, 0);
>>  		ufshcd_print_host_regs(hba);
>> @@ -6745,6 +6755,27 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
>>  		goto cleanup;
>>  	}
>> 
>> +	/*
>> +	 * Task abort to the device W-LUN is illegal. When this command
>> +	 * will fail, due to spec violation, scsi err handling next step
>> +	 * will be to send LU reset which, again, is a spec violation.
>> +	 * To avoid these unnecessary/illegal steps, first we clean up
>> +	 * the lrb taken by this cmd and mark the lrb as in_use, then
>> +	 * queue the eh_work and bail.
>> +	 */
>> +	if (lrbp->lun == UFS_UPIU_UFS_DEVICE_WLUN) {
>> +		spin_lock_irqsave(host->host_lock, flags);
>> +		if (lrbp->cmd) {
>> +			__ufshcd_transfer_req_compl(hba, (1UL << tag));
> 
> The timed out "tag" is cleared once here.
> 
>> +			__set_bit(tag, &hba->outstanding_reqs);
>> +			lrbp->in_use = true;
>> +			hba->force_reset = true;
>> +			ufshcd_schedule_eh_work(hba);
> 
> The same "tag" would be cleared again in error handler with
> __ufshcd_transfer_req_compl().
> 
> In __ufshcd_transfer_req_compl, hba->clk_scaling.active_reqs will be
> decreased if clk-scaling is supported as below,
> 
> 	if (ufshcd_is_clkscaling_supported(hba))
> 		hba->clk_scaling.active_reqs--;
> 
> Will be the hba->clk_scaling.active_reqs value become abnormal by this
> flow?
> 

Yes, it may undershoot. Actually the logic in 
__ufshcd_transfer_req_compl()
should be updated - clk_scaling.active_reqs should be updated only when
there are cmds (scsi or query) to complete. Here is not the only place 
which
can cause a undershoot. We can prevent the undershoot with below check.

  	if (ufshcd_is_clkscaling_supported(hba) &&
             hba->clk_scaling.active_reqs > 0)
  		hba->clk_scaling.active_reqs--;

Thanks,

Can Guo.

> Thanks,
> Stanley Chu
> 
>> +		}
>> +		spin_unlock_irqrestore(host->host_lock, flags);
>> +		goto out;
>> +	}
>> +
>>  	/* Skip task abort in case previous aborts failed and report failure 
>> */
>>  	if (lrbp->req_abort_skip)
>>  		err = -EIO;
>> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
>> index 1e680bf..66e5338 100644
>> --- a/drivers/scsi/ufs/ufshcd.h
>> +++ b/drivers/scsi/ufs/ufshcd.h
>> @@ -163,6 +163,7 @@ struct ufs_pm_lvl_states {
>>   * @crypto_key_slot: the key slot to use for inline crypto (-1 if 
>> none)
>>   * @data_unit_num: the data unit number for the first block for 
>> inline crypto
>>   * @req_abort_skip: skip request abort task flag
>> + * @in_use: indicates that this lrb is still in use
>>   */
>>  struct ufshcd_lrb {
>>  	struct utp_transfer_req_desc *utr_descriptor_ptr;
>> @@ -192,6 +193,7 @@ struct ufshcd_lrb {
>>  #endif
>> 
>>  	bool req_abort_skip;
>> +	bool in_use;
>>  };
>> 
>>  /**