linux-kernel - Re: [PATCH v4 2/2] scsi: ufs: handle LINERESET with correct tm

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Date:   Thu, 07 Jan 2021 16:17:55 +0800
From:   Can Guo <cang@...eaurora.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com, alim.akhtar@...sung.com,
        avri.altman@....com, bvanassche@....org,
        martin.petersen@...cle.com, stanley.chu@...iatek.com
Subject: Re: [PATCH v4 2/2] scsi: ufs: handle LINERESET with correct tm_cmd

On 2021-01-07 16:07, Jaegeuk Kim wrote:
> On 01/07, Can Guo wrote:
>> On 2021-01-07 15:47, Jaegeuk Kim wrote:
>> > From: Jaegeuk Kim <jaegeuk@...gle.com>
>> >
>> > This fixes a warning caused by wrong reserve tag usage in
>> > __ufshcd_issue_tm_cmd.
>> >
>> > WARNING: CPU: 7 PID: 7 at block/blk-core.c:630 blk_get_request+0x68/0x70
>> > WARNING: CPU: 4 PID: 157 at block/blk-mq-tag.c:82
>> > blk_mq_get_tag+0x438/0x46c
>> >
>> > And, in ufshcd_err_handler(), we can avoid to send tm_cmd before
>> > aborting
>> > outstanding commands by waiting a bit for IO completion like this.
>> >
>> > __ufshcd_issue_tm_cmd: task management cmd 0x80 timed-out
>> >
>> > Fixes: 69a6c269c097 ("scsi: ufs: Use blk_{get,put}_request() to
>> > allocate and free TMFs")
>> > Fixes: 2355b66ed20c ("scsi: ufs: Handle LINERESET indication in err
>> > handler")
>> 
>> Hi Jaegeuk,
>> 
>> Sorry, what is wrong with commit 2355b66ed20c? Clearing pending I/O
>> reqs is a general procedure for handling all non-fatal errors.
> 
> Without waiting IOs, I hit the below timeout all the time from 
> LINERESET, which
> causes UFS stuck permanently, as mentioned in the description.
> 
> "__ufshcd_issue_tm_cmd: task management cmd 0x80 timed-out"

In that case, ufshcd_try_to_abort_task(), the caller of 
__ufshcd_issue_tm_cmd(),
should return -ETIMEOUT, then err_handler would jump to do a full reset, 
then bail.
I am not sure what gets UFS stuck permanently. Could you please share 
the callstack
if possible? I really want to know what is happening. Thanks.

Regards,
Can Guo.

> 
>> 
>> Thanks,
>> Can Guo.
>> 
>> > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>> > ---
>> >  drivers/scsi/ufs/ufshcd.c | 35 +++++++++++++++++++++++++++++++----
>> >  1 file changed, 31 insertions(+), 4 deletions(-)
>> >
>> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> > index e6e7bdf99cd7..340dd5e515dd 100644
>> > --- a/drivers/scsi/ufs/ufshcd.c
>> > +++ b/drivers/scsi/ufs/ufshcd.c
>> > @@ -44,6 +44,9 @@
>> >  /* Query request timeout */
>> >  #define QUERY_REQ_TIMEOUT 1500 /* 1.5 seconds */
>> >
>> > +/* LINERESET TIME OUT */
>> > +#define LINERESET_IO_TIMEOUT_MS			(30000) /* 30 sec */
>> > +
>> >  /* Task management command timeout */
>> >  #define TM_CMD_TIMEOUT	100 /* msecs */
>> >
>> > @@ -5826,6 +5829,7 @@ static void ufshcd_err_handler(struct work_struct
>> > *work)
>> >  	int err = 0, pmc_err;
>> >  	int tag;
>> >  	bool needs_reset = false, needs_restore = false;
>> > +	ktime_t start;
>> >
>> >  	hba = container_of(work, struct ufs_hba, eh_work);
>> >
>> > @@ -5911,6 +5915,22 @@ static void ufshcd_err_handler(struct work_struct
>> > *work)
>> >  	}
>> >
>> >  	hba->silence_err_logs = true;
>> > +
>> > +	/* Wait for IO completion for non-fatal errors to avoid aborting IOs
>> > */
>> > +	start = ktime_get();
>> > +	while (hba->outstanding_reqs) {
>> > +		ufshcd_complete_requests(hba);
>> > +		spin_unlock_irqrestore(hba->host->host_lock, flags);
>> > +		schedule();
>> > +		spin_lock_irqsave(hba->host->host_lock, flags);
>> > +		if (ktime_to_ms(ktime_sub(ktime_get(), start)) >
>> > +						LINERESET_IO_TIMEOUT_MS) {
>> > +			dev_err(hba->dev, "%s: timeout, outstanding=0x%lx\n",
>> > +					__func__, hba->outstanding_reqs);
>> > +			break;
>> > +		}
>> > +	}
>> > +
>> >  	/* release lock as clear command might sleep */
>> >  	spin_unlock_irqrestore(hba->host->host_lock, flags);
>> >  	/* Clear pending transfer requests */
>> > @@ -6302,9 +6322,13 @@ static irqreturn_t ufshcd_intr(int irq, void
>> > *__hba)
>> >  		intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
>> >  	}
>> >
>> > -	if (enabled_intr_status && retval == IRQ_NONE) {
>> > -		dev_err(hba->dev, "%s: Unhandled interrupt 0x%08x\n",
>> > -					__func__, intr_status);
>> > +	if (enabled_intr_status && retval == IRQ_NONE &&
>> > +				!ufshcd_eh_in_progress(hba)) {
>> > +		dev_err(hba->dev, "%s: Unhandled interrupt 0x%08x (0x%08x,
>> > 0x%08x)\n",
>> > +					__func__,
>> > +					intr_status,
>> > +					hba->ufs_stats.last_intr_status,
>> > +					enabled_intr_status);
>> >  		ufshcd_dump_regs(hba, 0, UFSHCI_REG_SPACE_SIZE, "host_regs: ");
>> >  	}
>> >
>> > @@ -6348,7 +6372,10 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba
>> > *hba,
>> >  	 * Even though we use wait_event() which sleeps indefinitely,
>> >  	 * the maximum wait time is bounded by %TM_CMD_TIMEOUT.
>> >  	 */
>> > -	req = blk_get_request(q, REQ_OP_DRV_OUT, BLK_MQ_REQ_RESERVED);
>> > +	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);