[v3,2/2] scsi: ufs: handle LINERESET with correct tm_cmd

Commit Message

Jaegeuk Kim Jan. 6, 2021, 9:41 p.m. UTC

From: Jaegeuk Kim <[e-mail]>

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

Signed-off-by: Jaegeuk Kim <[e-mail]>
---
 drivers/scsi/ufs/ufshcd.c | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

Comments

Can Guo Jan. 7, 2021, 6:07 a.m. UTC | #1

Hi Jaegeuk,

On 2021-01-07 05:41, Jaegeuk Kim wrote:
> From: Jaegeuk Kim <[e-mail]>
> 
> 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
> 
> Signed-off-by: Jaegeuk Kim <[e-mail]>
> ---
>  drivers/scsi/ufs/ufshcd.c | 36 ++++++++++++++++++++++++++++++++----
>  1 file changed, 32 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 1678cec08b51..47fc8da3cbf9 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 */
> 
> @@ -5899,6 +5902,8 @@ static void ufshcd_err_handler(struct work_struct 
> *work)
>  	 * check if power mode restore is needed.
>  	 */
>  	if (hba->saved_uic_err & UFSHCD_UIC_PA_GENERIC_ERROR) {
> +		ktime_t start = ktime_get();

I don't see the connection btw line-reset and following tmf cmd.
My point is that line-reset is not the only non-fatal error which
leads us to the following tmf cmd. So the wait should be outside
of this check - just put it right before clearing outstanding reqs.

Thanks,
Can Guo.

> +
>  		hba->saved_uic_err &= ~UFSHCD_UIC_PA_GENERIC_ERROR;
>  		if (!hba->saved_uic_err)
>  			hba->saved_err &= ~UIC_ERROR;
> @@ -5906,6 +5911,20 @@ static void ufshcd_err_handler(struct 
> work_struct *work)
>  		if (ufshcd_is_pwr_mode_restore_needed(hba))
>  			needs_restore = true;
>  		spin_lock_irqsave(hba->host->host_lock, flags);
> +		/* Wait for IO completion to avoid aborting IOs */
> +		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;
> +			}
> +		}
> +
>  		if (!hba->saved_err && !needs_restore)
>  			goto skip_err_handling;
>  	}
> @@ -6302,9 +6321,13 @@ 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 +6371,11 @@ 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, BLK_MQ_REQ_RESERVED |
> +						BLK_MQ_REQ_NOWAIT);
> +	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);
> @@ -9355,6 +9382,7 @@ int ufshcd_init(struct ufs_hba *hba, void
> __iomem *mmio_base, unsigned int irq)
> 
>  	hba->tmf_tag_set = (struct blk_mq_tag_set) {
>  		.nr_hw_queues	= 1,
> +		.reserved_tags	= 1,
>  		.queue_depth	= hba->nutmrs,
>  		.ops		= &ufshcd_tmf_ops,
>  		.flags		= BLK_MQ_F_NO_SCHED,

Can Guo Jan. 7, 2021, 6:38 a.m. UTC | #2

On 2021-01-07 05:41, Jaegeuk Kim wrote:
> From: Jaegeuk Kim <[e-mail]>
> 
> 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
> 

Would you mind add a Fixes tag?

> Signed-off-by: Jaegeuk Kim <[e-mail]>
> ---
>  drivers/scsi/ufs/ufshcd.c | 36 ++++++++++++++++++++++++++++++++----
>  1 file changed, 32 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 1678cec08b51..47fc8da3cbf9 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 */
> 
> @@ -5899,6 +5902,8 @@ static void ufshcd_err_handler(struct work_struct 
> *work)
>  	 * check if power mode restore is needed.
>  	 */
>  	if (hba->saved_uic_err & UFSHCD_UIC_PA_GENERIC_ERROR) {
> +		ktime_t start = ktime_get();
> +
>  		hba->saved_uic_err &= ~UFSHCD_UIC_PA_GENERIC_ERROR;
>  		if (!hba->saved_uic_err)
>  			hba->saved_err &= ~UIC_ERROR;
> @@ -5906,6 +5911,20 @@ static void ufshcd_err_handler(struct 
> work_struct *work)
>  		if (ufshcd_is_pwr_mode_restore_needed(hba))
>  			needs_restore = true;
>  		spin_lock_irqsave(hba->host->host_lock, flags);
> +		/* Wait for IO completion to avoid aborting IOs */
> +		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;
> +			}
> +		}
> +
>  		if (!hba->saved_err && !needs_restore)
>  			goto skip_err_handling;
>  	}
> @@ -6302,9 +6321,13 @@ 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 +6371,11 @@ 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, BLK_MQ_REQ_RESERVED |
> +						BLK_MQ_REQ_NOWAIT);

Sorry that I didn't pay much attention to this part of code before.
May I know why must we use the BLK_MQ_REQ_RESERVED flag?

Thanks,
Can Guo.

> +	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);
> @@ -9355,6 +9382,7 @@ int ufshcd_init(struct ufs_hba *hba, void
> __iomem *mmio_base, unsigned int irq)
> 
>  	hba->tmf_tag_set = (struct blk_mq_tag_set) {
>  		.nr_hw_queues	= 1,
> +		.reserved_tags	= 1,

If we give reserved_tags as 1 and always ask for a tm requst with
BLK_MQ_REQ_RESERVED flag set, then the tag shall only be allocated
from the reserved sbitmap_queue, whose depth is set to 1 here.
UFS supports tm queue depth as 8, but here is allowing only one tm
req at a time. Why? Please correct me if my understanding is wrong.

Thanks,
Can Guo.

>  		.queue_depth	= hba->nutmrs,
>  		.ops		= &ufshcd_tmf_ops,
>  		.flags		= BLK_MQ_F_NO_SCHED,

Jaegeuk Kim Jan. 7, 2021, 6:51 a.m. UTC | #3

On 01/07, Can Guo wrote:
> On 2021-01-07 05:41, Jaegeuk Kim wrote:
> > From: Jaegeuk Kim <[e-mail]>
> > 
> > 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
> > 
> 
> Would you mind add a Fixes tag?

Ok.

> 
> > Signed-off-by: Jaegeuk Kim <[e-mail]>
> > ---
> >  drivers/scsi/ufs/ufshcd.c | 36 ++++++++++++++++++++++++++++++++----
> >  1 file changed, 32 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index 1678cec08b51..47fc8da3cbf9 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 */
> > 
> > @@ -5899,6 +5902,8 @@ static void ufshcd_err_handler(struct work_struct
> > *work)
> >  	 * check if power mode restore is needed.
> >  	 */
> >  	if (hba->saved_uic_err & UFSHCD_UIC_PA_GENERIC_ERROR) {
> > +		ktime_t start = ktime_get();
> > +
> >  		hba->saved_uic_err &= ~UFSHCD_UIC_PA_GENERIC_ERROR;
> >  		if (!hba->saved_uic_err)
> >  			hba->saved_err &= ~UIC_ERROR;
> > @@ -5906,6 +5911,20 @@ static void ufshcd_err_handler(struct work_struct
> > *work)
> >  		if (ufshcd_is_pwr_mode_restore_needed(hba))
> >  			needs_restore = true;
> >  		spin_lock_irqsave(hba->host->host_lock, flags);
> > +		/* Wait for IO completion to avoid aborting IOs */
> > +		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;
> > +			}
> > +		}
> > +
> >  		if (!hba->saved_err && !needs_restore)
> >  			goto skip_err_handling;
> >  	}
> > @@ -6302,9 +6321,13 @@ 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 +6371,11 @@ 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, BLK_MQ_REQ_RESERVED |
> > +						BLK_MQ_REQ_NOWAIT);
> 
> Sorry that I didn't pay much attention to this part of code before.
> May I know why must we use the BLK_MQ_REQ_RESERVED flag?

What I understood is the reserved tag is used when aborting outstanding
IOs when all the 32 tags were used.

> 
> Thanks,
> Can Guo.
> 
> > +	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);
> > @@ -9355,6 +9382,7 @@ int ufshcd_init(struct ufs_hba *hba, void
> > __iomem *mmio_base, unsigned int irq)
> > 
> >  	hba->tmf_tag_set = (struct blk_mq_tag_set) {
> >  		.nr_hw_queues	= 1,
> > +		.reserved_tags	= 1,
> 
> If we give reserved_tags as 1 and always ask for a tm requst with
> BLK_MQ_REQ_RESERVED flag set, then the tag shall only be allocated
> from the reserved sbitmap_queue, whose depth is set to 1 here.
> UFS supports tm queue depth as 8, but here is allowing only one tm
> req at a time. Why? Please correct me if my understanding is wrong.

I couldn't find tm can be issued in parallel, so thought it was issued
one at a time. If we set 8, then we can use 24 for IOs, IIUC.

Please correct me as well. I'm still trying to understand the flow.

> 
> Thanks,
> Can Guo.
> 
> >  		.queue_depth	= hba->nutmrs,
> >  		.ops		= &ufshcd_tmf_ops,
> >  		.flags		= BLK_MQ_F_NO_SCHED,

Jaegeuk Kim Jan. 7, 2021, 6:51 a.m. UTC | #4

On 01/07, Can Guo wrote:
> Hi Jaegeuk,
> 
> On 2021-01-07 05:41, Jaegeuk Kim wrote:
> > From: Jaegeuk Kim <[e-mail]>
> > 
> > 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
> > 
> > Signed-off-by: Jaegeuk Kim <[e-mail]>
> > ---
> >  drivers/scsi/ufs/ufshcd.c | 36 ++++++++++++++++++++++++++++++++----
> >  1 file changed, 32 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index 1678cec08b51..47fc8da3cbf9 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 */
> > 
> > @@ -5899,6 +5902,8 @@ static void ufshcd_err_handler(struct work_struct
> > *work)
> >  	 * check if power mode restore is needed.
> >  	 */
> >  	if (hba->saved_uic_err & UFSHCD_UIC_PA_GENERIC_ERROR) {
> > +		ktime_t start = ktime_get();
> 
> I don't see the connection btw line-reset and following tmf cmd.
> My point is that line-reset is not the only non-fatal error which
> leads us to the following tmf cmd. So the wait should be outside
> of this check - just put it right before clearing outstanding reqs.

Ok. Let me move it in v4.

> 
> Thanks,
> Can Guo.
> 
> > +
> >  		hba->saved_uic_err &= ~UFSHCD_UIC_PA_GENERIC_ERROR;
> >  		if (!hba->saved_uic_err)
> >  			hba->saved_err &= ~UIC_ERROR;
> > @@ -5906,6 +5911,20 @@ static void ufshcd_err_handler(struct work_struct
> > *work)
> >  		if (ufshcd_is_pwr_mode_restore_needed(hba))
> >  			needs_restore = true;
> >  		spin_lock_irqsave(hba->host->host_lock, flags);
> > +		/* Wait for IO completion to avoid aborting IOs */
> > +		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;
> > +			}
> > +		}
> > +
> >  		if (!hba->saved_err && !needs_restore)
> >  			goto skip_err_handling;
> >  	}
> > @@ -6302,9 +6321,13 @@ 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 +6371,11 @@ 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, BLK_MQ_REQ_RESERVED |
> > +						BLK_MQ_REQ_NOWAIT);
> > +	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);
> > @@ -9355,6 +9382,7 @@ int ufshcd_init(struct ufs_hba *hba, void
> > __iomem *mmio_base, unsigned int irq)
> > 
> >  	hba->tmf_tag_set = (struct blk_mq_tag_set) {
> >  		.nr_hw_queues	= 1,
> > +		.reserved_tags	= 1,
> >  		.queue_depth	= hba->nutmrs,
> >  		.ops		= &ufshcd_tmf_ops,
> >  		.flags		= BLK_MQ_F_NO_SCHED,

Can Guo Jan. 7, 2021, 7:03 a.m. UTC | #5

On 2021-01-07 14:51, Jaegeuk Kim wrote:
> On 01/07, Can Guo wrote:
>> On 2021-01-07 05:41, Jaegeuk Kim wrote:
>> > From: Jaegeuk Kim <[e-mail]>
>> >
>> > 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
>> >
>> 
>> Would you mind add a Fixes tag?
> 
> Ok.
> 
>> 
>> > Signed-off-by: Jaegeuk Kim <[e-mail]>
>> > ---
>> >  drivers/scsi/ufs/ufshcd.c | 36 ++++++++++++++++++++++++++++++++----
>> >  1 file changed, 32 insertions(+), 4 deletions(-)
>> >
>> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> > index 1678cec08b51..47fc8da3cbf9 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 */
>> >
>> > @@ -5899,6 +5902,8 @@ static void ufshcd_err_handler(struct work_struct
>> > *work)
>> >  	 * check if power mode restore is needed.
>> >  	 */
>> >  	if (hba->saved_uic_err & UFSHCD_UIC_PA_GENERIC_ERROR) {
>> > +		ktime_t start = ktime_get();
>> > +
>> >  		hba->saved_uic_err &= ~UFSHCD_UIC_PA_GENERIC_ERROR;
>> >  		if (!hba->saved_uic_err)
>> >  			hba->saved_err &= ~UIC_ERROR;
>> > @@ -5906,6 +5911,20 @@ static void ufshcd_err_handler(struct work_struct
>> > *work)
>> >  		if (ufshcd_is_pwr_mode_restore_needed(hba))
>> >  			needs_restore = true;
>> >  		spin_lock_irqsave(hba->host->host_lock, flags);
>> > +		/* Wait for IO completion to avoid aborting IOs */
>> > +		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;
>> > +			}
>> > +		}
>> > +
>> >  		if (!hba->saved_err && !needs_restore)
>> >  			goto skip_err_handling;
>> >  	}
>> > @@ -6302,9 +6321,13 @@ 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 +6371,11 @@ 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, BLK_MQ_REQ_RESERVED |
>> > +						BLK_MQ_REQ_NOWAIT);
>> 
>> Sorry that I didn't pay much attention to this part of code before.
>> May I know why must we use the BLK_MQ_REQ_RESERVED flag?
> 
> What I understood is the reserved tag is used when aborting outstanding
> IOs when all the 32 tags were used.
> 

No, the tm requests and I/O requests are on two different tag sets:
tm requests come from hba->tmf_tag_set, while I/O requests come from
hba->shost->tag_set. Meaning they don't share tags with each other.

>> 
>> Thanks,
>> Can Guo.
>> 
>> > +	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);
>> > @@ -9355,6 +9382,7 @@ int ufshcd_init(struct ufs_hba *hba, void
>> > __iomem *mmio_base, unsigned int irq)
>> >
>> >  	hba->tmf_tag_set = (struct blk_mq_tag_set) {
>> >  		.nr_hw_queues	= 1,
>> > +		.reserved_tags	= 1,
>> 
>> If we give reserved_tags as 1 and always ask for a tm requst with
>> BLK_MQ_REQ_RESERVED flag set, then the tag shall only be allocated
>> from the reserved sbitmap_queue, whose depth is set to 1 here.
>> UFS supports tm queue depth as 8, but here is allowing only one tm
>> req at a time. Why? Please correct me if my understanding is wrong.
> 
> I couldn't find tm can be issued in parallel, so thought it was issued
> one at a time. If we set 8, then we can use 24 for IOs, IIUC.
> 
> Please correct me as well. I'm still trying to understand the flow.
> 

UFS allows a queue depth as 8, which means it support sending multiple
tm requests at the same time. You can check commit 69a6c269c097d780a2 -
before this change, we used to use below func to allocate tags for
tm reqs, which can tell you the true story.

So I am thinking why don't we just we remove the BLK_MQ_REQ_RESERVED 
flag?
Removing it can also fix the warning I suppose. What do you think?

-static bool ufshcd_get_tm_free_slot(struct ufs_hba *hba, int 
*free_slot)
-{
-       int tag;
-       bool ret = false;
-
-       if (!free_slot)
-               goto out;
-
-       do {
-               tag = find_first_zero_bit(&hba->tm_slots_in_use, 
hba->nutmrs);
-               if (tag >= hba->nutmrs)
-                       goto out;
-       } while (test_and_set_bit_lock(tag, &hba->tm_slots_in_use));
-
-       *free_slot = tag;
-       ret = true;
-out:
-       return ret;
-}

Thanks,
Can Guo.

>> 
>> Thanks,
>> Can Guo.
>> 
>> >  		.queue_depth	= hba->nutmrs,
>> >  		.ops		= &ufshcd_tmf_ops,
>> >  		.flags		= BLK_MQ_F_NO_SCHED,

Can Guo Jan. 7, 2021, 7:20 a.m. UTC | #6

On 2021-01-07 15:03, Can Guo wrote:
> On 2021-01-07 14:51, Jaegeuk Kim wrote:
>> On 01/07, Can Guo wrote:
>>> On 2021-01-07 05:41, Jaegeuk Kim wrote:
>>> > From: Jaegeuk Kim <[e-mail]>
>>> >
>>> > 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
>>> >
>>> 
>>> Would you mind add a Fixes tag?
>> 
>> Ok.
>> 
>>> 
>>> > Signed-off-by: Jaegeuk Kim <[e-mail]>
>>> > ---
>>> >  drivers/scsi/ufs/ufshcd.c | 36 ++++++++++++++++++++++++++++++++----
>>> >  1 file changed, 32 insertions(+), 4 deletions(-)
>>> >
>>> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>>> > index 1678cec08b51..47fc8da3cbf9 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 */
>>> >
>>> > @@ -5899,6 +5902,8 @@ static void ufshcd_err_handler(struct work_struct
>>> > *work)
>>> >  	 * check if power mode restore is needed.
>>> >  	 */
>>> >  	if (hba->saved_uic_err & UFSHCD_UIC_PA_GENERIC_ERROR) {
>>> > +		ktime_t start = ktime_get();
>>> > +
>>> >  		hba->saved_uic_err &= ~UFSHCD_UIC_PA_GENERIC_ERROR;
>>> >  		if (!hba->saved_uic_err)
>>> >  			hba->saved_err &= ~UIC_ERROR;
>>> > @@ -5906,6 +5911,20 @@ static void ufshcd_err_handler(struct work_struct
>>> > *work)
>>> >  		if (ufshcd_is_pwr_mode_restore_needed(hba))
>>> >  			needs_restore = true;
>>> >  		spin_lock_irqsave(hba->host->host_lock, flags);
>>> > +		/* Wait for IO completion to avoid aborting IOs */
>>> > +		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;
>>> > +			}
>>> > +		}
>>> > +
>>> >  		if (!hba->saved_err && !needs_restore)
>>> >  			goto skip_err_handling;
>>> >  	}
>>> > @@ -6302,9 +6321,13 @@ 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 +6371,11 @@ 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, BLK_MQ_REQ_RESERVED |
>>> > +						BLK_MQ_REQ_NOWAIT);
>>> 
>>> Sorry that I didn't pay much attention to this part of code before.
>>> May I know why must we use the BLK_MQ_REQ_RESERVED flag?
>> 
>> What I understood is the reserved tag is used when aborting 
>> outstanding
>> IOs when all the 32 tags were used.
>> 
> 
> No, the tm requests and I/O requests are on two different tag sets:
> tm requests come from hba->tmf_tag_set, while I/O requests come from
> hba->shost->tag_set. Meaning they don't share tags with each other.

Add they are issued on two different HW queues - one for tm reqs,
one for I/O reqs, which is why two different tag sets are created.

> 
>>> 
>>> Thanks,
>>> Can Guo.
>>> 
>>> > +	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);
>>> > @@ -9355,6 +9382,7 @@ int ufshcd_init(struct ufs_hba *hba, void
>>> > __iomem *mmio_base, unsigned int irq)
>>> >
>>> >  	hba->tmf_tag_set = (struct blk_mq_tag_set) {
>>> >  		.nr_hw_queues	= 1,
>>> > +		.reserved_tags	= 1,
>>> 
>>> If we give reserved_tags as 1 and always ask for a tm requst with
>>> BLK_MQ_REQ_RESERVED flag set, then the tag shall only be allocated
>>> from the reserved sbitmap_queue, whose depth is set to 1 here.
>>> UFS supports tm queue depth as 8, but here is allowing only one tm
>>> req at a time. Why? Please correct me if my understanding is wrong.
>> 
>> I couldn't find tm can be issued in parallel, so thought it was issued
>> one at a time. If we set 8, then we can use 24 for IOs, IIUC.
>> 
>> Please correct me as well. I'm still trying to understand the flow.
>> 
> 
> UFS allows a queue depth as 8, which means it support sending multiple
> tm requests at the same time. You can check commit 69a6c269c097d780a2 -
> before this change, we used to use below func to allocate tags for
> tm reqs, which can tell you the true story.
> 
> So I am thinking why don't we just we remove the BLK_MQ_REQ_RESERVED 
> flag?
> Removing it can also fix the warning I suppose. What do you think?
> 
> -static bool ufshcd_get_tm_free_slot(struct ufs_hba *hba, int 
> *free_slot)
> -{
> -       int tag;
> -       bool ret = false;
> -
> -       if (!free_slot)
> -               goto out;
> -
> -       do {
> -               tag = find_first_zero_bit(&hba->tm_slots_in_use, 
> hba->nutmrs);
> -               if (tag >= hba->nutmrs)
> -                       goto out;
> -       } while (test_and_set_bit_lock(tag, &hba->tm_slots_in_use));
> -
> -       *free_slot = tag;
> -       ret = true;
> -out:
> -       return ret;
> -}
> 
> Thanks,
> Can Guo.
> 
>>> 
>>> Thanks,
>>> Can Guo.
>>> 
>>> >  		.queue_depth	= hba->nutmrs,
>>> >  		.ops		= &ufshcd_tmf_ops,
>>> >  		.flags		= BLK_MQ_F_NO_SCHED,

Jaegeuk Kim Jan. 7, 2021, 7:23 a.m. UTC | #7

On 01/07, Can Guo wrote:
> On 2021-01-07 14:51, Jaegeuk Kim wrote:
> > On 01/07, Can Guo wrote:
> > > On 2021-01-07 05:41, Jaegeuk Kim wrote:
> > > > From: Jaegeuk Kim <[e-mail]>
> > > >
> > > > 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
> > > >
> > > 
> > > Would you mind add a Fixes tag?
> > 
> > Ok.
> > 
> > > 
> > > > Signed-off-by: Jaegeuk Kim <[e-mail]>
> > > > ---
> > > >  drivers/scsi/ufs/ufshcd.c | 36 ++++++++++++++++++++++++++++++++----
> > > >  1 file changed, 32 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > > > index 1678cec08b51..47fc8da3cbf9 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 */
> > > >
> > > > @@ -5899,6 +5902,8 @@ static void ufshcd_err_handler(struct work_struct
> > > > *work)
> > > >  	 * check if power mode restore is needed.
> > > >  	 */
> > > >  	if (hba->saved_uic_err & UFSHCD_UIC_PA_GENERIC_ERROR) {
> > > > +		ktime_t start = ktime_get();
> > > > +
> > > >  		hba->saved_uic_err &= ~UFSHCD_UIC_PA_GENERIC_ERROR;
> > > >  		if (!hba->saved_uic_err)
> > > >  			hba->saved_err &= ~UIC_ERROR;
> > > > @@ -5906,6 +5911,20 @@ static void ufshcd_err_handler(struct work_struct
> > > > *work)
> > > >  		if (ufshcd_is_pwr_mode_restore_needed(hba))
> > > >  			needs_restore = true;
> > > >  		spin_lock_irqsave(hba->host->host_lock, flags);
> > > > +		/* Wait for IO completion to avoid aborting IOs */
> > > > +		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;
> > > > +			}
> > > > +		}
> > > > +
> > > >  		if (!hba->saved_err && !needs_restore)
> > > >  			goto skip_err_handling;
> > > >  	}
> > > > @@ -6302,9 +6321,13 @@ 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 +6371,11 @@ 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, BLK_MQ_REQ_RESERVED |
> > > > +						BLK_MQ_REQ_NOWAIT);
> > > 
> > > Sorry that I didn't pay much attention to this part of code before.
> > > May I know why must we use the BLK_MQ_REQ_RESERVED flag?
> > 
> > What I understood is the reserved tag is used when aborting outstanding
> > IOs when all the 32 tags were used.
> > 
> 
> No, the tm requests and I/O requests are on two different tag sets:
> tm requests come from hba->tmf_tag_set, while I/O requests come from
> hba->shost->tag_set. Meaning they don't share tags with each other.

I see. :)

> 
> > > 
> > > Thanks,
> > > Can Guo.
> > > 
> > > > +	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);
> > > > @@ -9355,6 +9382,7 @@ int ufshcd_init(struct ufs_hba *hba, void
> > > > __iomem *mmio_base, unsigned int irq)
> > > >
> > > >  	hba->tmf_tag_set = (struct blk_mq_tag_set) {
> > > >  		.nr_hw_queues	= 1,
> > > > +		.reserved_tags	= 1,
> > > 
> > > If we give reserved_tags as 1 and always ask for a tm requst with
> > > BLK_MQ_REQ_RESERVED flag set, then the tag shall only be allocated
> > > from the reserved sbitmap_queue, whose depth is set to 1 here.
> > > UFS supports tm queue depth as 8, but here is allowing only one tm
> > > req at a time. Why? Please correct me if my understanding is wrong.
> > 
> > I couldn't find tm can be issued in parallel, so thought it was issued
> > one at a time. If we set 8, then we can use 24 for IOs, IIUC.
> > 
> > Please correct me as well. I'm still trying to understand the flow.
> > 
> 
> UFS allows a queue depth as 8, which means it support sending multiple
> tm requests at the same time. You can check commit 69a6c269c097d780a2 -
> before this change, we used to use below func to allocate tags for
> tm reqs, which can tell you the true story.
> 
> So I am thinking why don't we just we remove the BLK_MQ_REQ_RESERVED flag?
> Removing it can also fix the warning I suppose. What do you think?

Yeah, I believe it won't give a warning. Okay, let me check it out.

> 
> -static bool ufshcd_get_tm_free_slot(struct ufs_hba *hba, int *free_slot)
> -{
> -       int tag;
> -       bool ret = false;
> -
> -       if (!free_slot)
> -               goto out;
> -
> -       do {
> -               tag = find_first_zero_bit(&hba->tm_slots_in_use,
> hba->nutmrs);
> -               if (tag >= hba->nutmrs)
> -                       goto out;
> -       } while (test_and_set_bit_lock(tag, &hba->tm_slots_in_use));
> -
> -       *free_slot = tag;
> -       ret = true;
> -out:
> -       return ret;
> -}
> 
> Thanks,
> Can Guo.
> 
> > > 
> > > Thanks,
> > > Can Guo.
> > > 
> > > >  		.queue_depth	= hba->nutmrs,
> > > >  		.ops		= &ufshcd_tmf_ops,
> > > >  		.flags		= BLK_MQ_F_NO_SCHED,

Patch

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 1678cec08b51..47fc8da3cbf9 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 */
 
@@ -5899,6 +5902,8 @@  static void ufshcd_err_handler(struct work_struct *work)
 	 * check if power mode restore is needed.
 	 */
 	if (hba->saved_uic_err & UFSHCD_UIC_PA_GENERIC_ERROR) {
+		ktime_t start = ktime_get();
+
 		hba->saved_uic_err &= ~UFSHCD_UIC_PA_GENERIC_ERROR;
 		if (!hba->saved_uic_err)
 			hba->saved_err &= ~UIC_ERROR;
@@ -5906,6 +5911,20 @@  static void ufshcd_err_handler(struct work_struct *work)
 		if (ufshcd_is_pwr_mode_restore_needed(hba))
 			needs_restore = true;
 		spin_lock_irqsave(hba->host->host_lock, flags);
+		/* Wait for IO completion to avoid aborting IOs */
+		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;
+			}
+		}
+
 		if (!hba->saved_err && !needs_restore)
 			goto skip_err_handling;
 	}
@@ -6302,9 +6321,13 @@  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 +6371,11 @@  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, BLK_MQ_REQ_RESERVED |
+						BLK_MQ_REQ_NOWAIT);
+	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);
@@ -9355,6 +9382,7 @@  int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 
 	hba->tmf_tag_set = (struct blk_mq_tag_set) {
 		.nr_hw_queues	= 1,
+		.reserved_tags	= 1,
 		.queue_depth	= hba->nutmrs,
 		.ops		= &ufshcd_tmf_ops,
 		.flags		= BLK_MQ_F_NO_SCHED,