2021-03-31 04:52:41

by Can Guo

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

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 <[email protected]>
---
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.

2021-03-31 16:48:12

by Avri Altman

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

> 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 <[email protected]>
> ---
> 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.

2021-04-01 03:00:18

by Can Guo

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

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 <[email protected]>
>> ---
>> 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.

2021-04-01 03:41:44

by Bart Van Assche

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

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 <[email protected]>
>> ---
>> 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.