[PATCH v4 0/2] Two fixes for task management request implementation

[PATCH v4 0/2] Two fixes for task management request implementation

[Can Guo]

These fixes are based on Jaegeuk's change - https://git.kernel.org/mkp/scsi/c/eeb1b55b6e25

Change since v3:
- Deleted the 2nd change
- Incorporated Bart's comments

Change since v2:
- Split one change into 3 changes

Change since v1:
- Typo fixed

Can Guo (2):
  scsi: ufs: Fix task management request completion timeout
  scsi: ufs: Fix wrong Task Tag used in task management request UPIUs

 drivers/scsi/ufs/ufshcd.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

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

[PATCH v4 1/2] scsi: ufs: Fix task management request completion timeout

[Can Guo]

ufshcd_tmc_handler() calls blk_mq_tagset_busy_iter(fn = ufshcd_compl_tm()),
but since blk_mq_tagset_busy_iter() only iterates over all reserved tags
and requests which are not in IDLE state, ufshcd_compl_tm() never gets a
chance to run. Thus, TMR always ends up with completion timeout. Fix it by
calling blk_mq_start_request() in  __ufshcd_issue_tm_cmd().

Fixes: 69a6c269c097 ("scsi: ufs: Use blk_{get,put}_request() to allocate and free TMFs")

Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index b49555fa..d4f8cb2 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6464,6 +6464,7 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba,
 
 	spin_lock_irqsave(host->host_lock, flags);
 	task_tag = hba->nutrs + free_slot;
+	blk_mq_start_request(req);
 
 	treq->req_header.dword_0 |= cpu_to_be32(task_tag);
 
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

[PATCH v4 2/2] scsi: ufs: Fix wrong Task Tag used in task management request UPIUs

[Can Guo]

In __ufshcd_issue_tm_cmd(), it is not right to use hba->nutrs + req->tag as
the Task Tag in one TMR UPIU. Directly use req->tag as the Task Tag.

Fixes: e293313262d3 ("scsi: ufs: Fix broken task management command implementation")

Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index d4f8cb2..cdd8c3d 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6446,38 +6446,35 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba,
 	DECLARE_COMPLETION_ONSTACK(wait);
 	struct request *req;
 	unsigned long flags;
-	int free_slot, task_tag, err;
+	int task_tag, err;
 
 	/*
-	 * Get free slot, sleep if slots are unavailable.
-	 * Even though we use wait_event() which sleeps indefinitely,
-	 * the maximum wait time is bounded by %TM_CMD_TIMEOUT.
+	 * blk_get_request() is used here only to get a free tag.
 	 */
 	req = blk_get_request(q, REQ_OP_DRV_OUT, 0);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
 	req->end_io_data = &wait;
-	free_slot = req->tag;
 	WARN_ON_ONCE(free_slot < 0 || free_slot >= hba->nutmrs);
 	ufshcd_hold(hba, false);
 
 	spin_lock_irqsave(host->host_lock, flags);
-	task_tag = hba->nutrs + free_slot;
 	blk_mq_start_request(req);
 
+	task_tag = req->tag;
 	treq->req_header.dword_0 |= cpu_to_be32(task_tag);
 
-	memcpy(hba->utmrdl_base_addr + free_slot, treq, sizeof(*treq));
-	ufshcd_vops_setup_task_mgmt(hba, free_slot, tm_function);
+	memcpy(hba->utmrdl_base_addr + task_tag, treq, sizeof(*treq));
+	ufshcd_vops_setup_task_mgmt(hba, task_tag, tm_function);
 
 	/* send command to the controller */
-	__set_bit(free_slot, &hba->outstanding_tasks);
+	__set_bit(task_tag, &hba->outstanding_tasks);
 
 	/* Make sure descriptors are ready before ringing the task doorbell */
 	wmb();
 
-	ufshcd_writel(hba, 1 << free_slot, REG_UTP_TASK_REQ_DOOR_BELL);
+	ufshcd_writel(hba, 1 << task_tag, REG_UTP_TASK_REQ_DOOR_BELL);
 	/* Make sure that doorbell is committed immediately */
 	wmb();
 
@@ -6497,24 +6494,24 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba,
 		ufshcd_add_tm_upiu_trace(hba, task_tag, UFS_TM_ERR);
 		dev_err(hba->dev, "%s: task management cmd 0x%.2x timed-out\n",
 				__func__, tm_function);
-		if (ufshcd_clear_tm_cmd(hba, free_slot))
-			dev_WARN(hba->dev, "%s: unable clear tm cmd (slot %d) after timeout\n",
-					__func__, free_slot);
+		if (ufshcd_clear_tm_cmd(hba, task_tag))
+			dev_WARN(hba->dev, "%s: unable to clear tm cmd (slot %d) after timeout\n",
+					__func__, task_tag);
 		err = -ETIMEDOUT;
 	} else {
 		err = 0;
-		memcpy(treq, hba->utmrdl_base_addr + free_slot, sizeof(*treq));
+		memcpy(treq, hba->utmrdl_base_addr + task_tag, sizeof(*treq));
 
 		ufshcd_add_tm_upiu_trace(hba, task_tag, UFS_TM_COMP);
 	}
 
 	spin_lock_irqsave(hba->host->host_lock, flags);
-	__clear_bit(free_slot, &hba->outstanding_tasks);
+	__clear_bit(task_tag, &hba->outstanding_tasks);
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 
+	ufshcd_release(hba);
 	blk_put_request(req);
 
-	ufshcd_release(hba);
 	return err;
 }
 
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

RE: [PATCH v4 1/2] scsi: ufs: Fix task management request completion timeout

[Avri Altman]

> ufshcd_tmc_handler() calls blk_mq_tagset_busy_iter(fn =
> ufshcd_compl_tm()),
> but since blk_mq_tagset_busy_iter() only iterates over all reserved tags
> and requests which are not in IDLE state, ufshcd_compl_tm() never gets a
> chance to run. Thus, TMR always ends up with completion timeout. Fix it by
> calling blk_mq_start_request() in  __ufshcd_issue_tm_cmd().
> 
> Fixes: 69a6c269c097 ("scsi: ufs: Use blk_{get,put}_request() to allocate and
> free TMFs")
> 
> Signed-off-by: Can Guo <cang@codeaurora.org>
> ---
>  drivers/scsi/ufs/ufshcd.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index b49555fa..d4f8cb2 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -6464,6 +6464,7 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba
> *hba,
> 
>         spin_lock_irqsave(host->host_lock, flags);
>         task_tag = hba->nutrs + free_slot;
> +       blk_mq_start_request(req);
Maybe just set req->state to MQ_RQ_IN_FLIGHT
Without all other irrelevant initializations such as add timeout etc.

Thanks,
Avri
> 
>         treq->req_header.dword_0 |= cpu_to_be32(task_tag);
> 
> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a
> Linux Foundation Collaborative Project.

Re: [PATCH v4 1/2] scsi: ufs: Fix task management request completion timeout

[Can Guo]

On 2021-04-01 00:45, Avri Altman wrote:
>> ufshcd_tmc_handler() calls blk_mq_tagset_busy_iter(fn =
>> ufshcd_compl_tm()),
>> but since blk_mq_tagset_busy_iter() only iterates over all reserved 
>> tags
>> and requests which are not in IDLE state, ufshcd_compl_tm() never gets 
>> a
>> chance to run. Thus, TMR always ends up with completion timeout. Fix 
>> it by
>> calling blk_mq_start_request() in  __ufshcd_issue_tm_cmd().
>> 
>> Fixes: 69a6c269c097 ("scsi: ufs: Use blk_{get,put}_request() to 
>> allocate and
>> free TMFs")
>> 
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> ---
>>  drivers/scsi/ufs/ufshcd.c | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index b49555fa..d4f8cb2 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -6464,6 +6464,7 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba
>> *hba,
>> 
>>         spin_lock_irqsave(host->host_lock, flags);
>>         task_tag = hba->nutrs + free_slot;
>> +       blk_mq_start_request(req);
> Maybe just set req->state to MQ_RQ_IN_FLIGHT
> Without all other irrelevant initializations such as add timeout etc.
> 

I don't see any other drivers do that, is it appropriate
to call WRITE_ONCE(rq->state, MQ_RQ_IN_FLIGHT) outside
block layer?

Thanks,
Can Guo.

> Thanks,
> Avri
>> 
>>         treq->req_header.dword_0 |= cpu_to_be32(task_tag);
>> 
>> --
>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a
>> Linux Foundation Collaborative Project.

Re: [PATCH v4 1/2] scsi: ufs: Fix task management request completion timeout

[Bart Van Assche]

On 3/31/21 9:45 AM, Avri Altman wrote:
>> ufshcd_tmc_handler() calls blk_mq_tagset_busy_iter(fn =
>> ufshcd_compl_tm()),
>> but since blk_mq_tagset_busy_iter() only iterates over all reserved tags
>> and requests which are not in IDLE state, ufshcd_compl_tm() never gets a
>> chance to run. Thus, TMR always ends up with completion timeout. Fix it by
>> calling blk_mq_start_request() in  __ufshcd_issue_tm_cmd().
>>
>> Fixes: 69a6c269c097 ("scsi: ufs: Use blk_{get,put}_request() to allocate and
>> free TMFs")
>>
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> ---
>>  drivers/scsi/ufs/ufshcd.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index b49555fa..d4f8cb2 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -6464,6 +6464,7 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba
>> *hba,
>>
>>         spin_lock_irqsave(host->host_lock, flags);
>>         task_tag = hba->nutrs + free_slot;
>> +       blk_mq_start_request(req);
> Maybe just set req->state to MQ_RQ_IN_FLIGHT
> Without all other irrelevant initializations such as add timeout etc.

Hmm ... I'm not sure that any of the actions performed by
blk_mq_start_request() are irrelevant in this context. Additionally, no
other block or SCSI driver sets MQ_RQ_IN_FLIGHT directly.

Thanks,

Bart.