(no subject)

[Jaegeuk Kim]

Change log from v3:
 - use __ufshcd_release with a fix in __ufshcd_release

Change log from v2:
 - use active_req-- instead of __ufshcd_release to avoid UFS timeout

Change log from v1:
 - remove clkgating_enable check in __ufshcd_release
 - use __uhfshcd_release instead of active_req.

[PATCH v4 1/5] scsi: ufs: atomic update for clkgating_enable

[Jaegeuk Kim]

From: Jaegeuk Kim <jaegeuk@google.com>

When giving a stress test which enables/disables clkgating, we hit device
timeout sometimes. This patch avoids subtle racy condition to address it.

Note that, this requires a patch to address the device stuck by REQ_CLKS_OFF in
__ufshcd_release().

The fix is "scsi: ufs: avoid to call REQ_CLKS_OFF to CLKS_OFF".

Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
---
 drivers/scsi/ufs/ufshcd.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index cc8d5f0c3fdc..6c9269bffcbd 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1808,19 +1808,19 @@ static ssize_t ufshcd_clkgate_enable_store(struct device *dev,
 		return -EINVAL;
 
 	value = !!value;
+
+	spin_lock_irqsave(hba->host->host_lock, flags);
 	if (value == hba->clk_gating.is_enabled)
 		goto out;
 
-	if (value) {
-		ufshcd_release(hba);
-	} else {
-		spin_lock_irqsave(hba->host->host_lock, flags);
+	if (value)
+		__ufshcd_release(hba);
+	else
 		hba->clk_gating.active_reqs++;
-		spin_unlock_irqrestore(hba->host->host_lock, flags);
-	}
 
 	hba->clk_gating.is_enabled = value;
 out:
+	spin_unlock_irqrestore(hba->host->host_lock, flags);
 	return count;
 }
 
-- 
2.29.0.rc1.297.gfa9743e501-goog

[PATCH v4 2/5] scsi: ufs: clear UAC for FFU and RPMB LUNs

[Jaegeuk Kim]

From: Jaegeuk Kim <jaegeuk@google.com>

In order to conduct FFU or RPMB operations, UFS needs to clear UAC. This patch
clears it explicitly, so that we could get no failure given early execution.

Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
---
 drivers/scsi/ufs/ufshcd.c | 70 +++++++++++++++++++++++++++++++++++----
 drivers/scsi/ufs/ufshcd.h |  1 +
 2 files changed, 65 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 6c9269bffcbd..8e696ca79b40 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -7058,7 +7058,6 @@ static inline void ufshcd_blk_pm_runtime_init(struct scsi_device *sdev)
 static int ufshcd_scsi_add_wlus(struct ufs_hba *hba)
 {
 	int ret = 0;
-	struct scsi_device *sdev_rpmb;
 	struct scsi_device *sdev_boot;
 
 	hba->sdev_ufs_device = __scsi_add_device(hba->host, 0, 0,
@@ -7071,14 +7070,14 @@ static int ufshcd_scsi_add_wlus(struct ufs_hba *hba)
 	ufshcd_blk_pm_runtime_init(hba->sdev_ufs_device);
 	scsi_device_put(hba->sdev_ufs_device);
 
-	sdev_rpmb = __scsi_add_device(hba->host, 0, 0,
+	hba->sdev_rpmb = __scsi_add_device(hba->host, 0, 0,
 		ufshcd_upiu_wlun_to_scsi_wlun(UFS_UPIU_RPMB_WLUN), NULL);
-	if (IS_ERR(sdev_rpmb)) {
-		ret = PTR_ERR(sdev_rpmb);
+	if (IS_ERR(hba->sdev_rpmb)) {
+		ret = PTR_ERR(hba->sdev_rpmb);
 		goto remove_sdev_ufs_device;
 	}
-	ufshcd_blk_pm_runtime_init(sdev_rpmb);
-	scsi_device_put(sdev_rpmb);
+	ufshcd_blk_pm_runtime_init(hba->sdev_rpmb);
+	scsi_device_put(hba->sdev_rpmb);
 
 	sdev_boot = __scsi_add_device(hba->host, 0, 0,
 		ufshcd_upiu_wlun_to_scsi_wlun(UFS_UPIU_BOOT_WLUN), NULL);
@@ -7602,6 +7601,63 @@ static int ufshcd_add_lus(struct ufs_hba *hba)
 	return ret;
 }
 
+static int
+ufshcd_send_request_sense(struct ufs_hba *hba, struct scsi_device *sdp);
+
+static int ufshcd_clear_ua_wlun(struct ufs_hba *hba, u8 wlun)
+{
+	struct scsi_device *sdp;
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(hba->host->host_lock, flags);
+	if (wlun  == UFS_UPIU_UFS_DEVICE_WLUN)
+		sdp = hba->sdev_ufs_device;
+	else if (wlun  == UFS_UPIU_RPMB_WLUN)
+		sdp = hba->sdev_rpmb;
+	else
+		BUG_ON(1);
+	if (sdp) {
+		ret = scsi_device_get(sdp);
+		if (!ret && !scsi_device_online(sdp)) {
+			ret = -ENODEV;
+			scsi_device_put(sdp);
+		}
+	} else {
+		ret = -ENODEV;
+	}
+	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	if (ret)
+		goto out_err;
+
+	ret = ufshcd_send_request_sense(hba, sdp);
+	scsi_device_put(sdp);
+out_err:
+	if (ret)
+		dev_err(hba->dev, "%s: UAC clear LU=%x ret = %d\n",
+				__func__, wlun, ret);
+	return ret;
+}
+
+static int ufshcd_clear_ua_wluns(struct ufs_hba *hba)
+{
+	int ret = 0;
+
+	if (!hba->wlun_dev_clr_ua)
+		goto out;
+
+	ret = ufshcd_clear_ua_wlun(hba, UFS_UPIU_UFS_DEVICE_WLUN);
+	if (!ret)
+		ret = ufshcd_clear_ua_wlun(hba, UFS_UPIU_RPMB_WLUN);
+	if (!ret)
+		hba->wlun_dev_clr_ua = false;
+out:
+	if (ret)
+		dev_err(hba->dev, "%s: Failed to clear UAC WLUNS ret = %d\n",
+				__func__, ret);
+	return ret;
+}
+
 /**
  * ufshcd_probe_hba - probe hba to detect device and initialize
  * @hba: per-adapter instance
@@ -7721,6 +7777,8 @@ static void ufshcd_async_scan(void *data, async_cookie_t cookie)
 		pm_runtime_put_sync(hba->dev);
 		ufshcd_exit_clk_scaling(hba);
 		ufshcd_hba_exit(hba);
+	} else {
+		ufshcd_clear_ua_wluns(hba);
 	}
 }
 
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 47eb1430274c..718881d038f5 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -681,6 +681,7 @@ struct ufs_hba {
 	 * "UFS device" W-LU.
 	 */
 	struct scsi_device *sdev_ufs_device;
+	struct scsi_device *sdev_rpmb;
 
 	enum ufs_dev_pwr_mode curr_dev_pwr_mode;
 	enum uic_link_state uic_link_state;
-- 
2.29.0.rc1.297.gfa9743e501-goog

[PATCH v4 3/5] scsi: ufs: use WQ_HIGHPRI for gating work

[Jaegeuk Kim]

From: Jaegeuk Kim <jaegeuk@google.com>

Must have WQ_MEM_RECLAIM
``WQ_MEM_RECLAIM``
  All wq which might be used in the memory reclaim paths **MUST**
  have this flag set.  The wq is guaranteed to have at least one
  execution context regardless of memory pressure.

Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 8e696ca79b40..c45c0cff174e 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1868,7 +1868,7 @@ static void ufshcd_init_clk_gating(struct ufs_hba *hba)
 	snprintf(wq_name, ARRAY_SIZE(wq_name), "ufs_clk_gating_%d",
 		 hba->host->host_no);
 	hba->clk_gating.clk_gating_workq = alloc_ordered_workqueue(wq_name,
-							   WQ_MEM_RECLAIM);
+					WQ_MEM_RECLAIM | WQ_HIGHPRI);
 
 	hba->clk_gating.is_enabled = true;
 
-- 
2.29.0.rc1.297.gfa9743e501-goog

[PATCH v4 4/5] scsi: add more contexts in the ufs tracepoints

[Jaegeuk Kim]

From: Jaegeuk Kim <jaegeuk@google.com>

This adds user-friendly tracepoints with group id.

Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Reviewed-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c  |  6 ++++--
 include/trace/events/ufs.h | 21 +++++++++++++++++----
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index c45c0cff174e..b8a54d09e750 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -348,7 +348,7 @@ static void ufshcd_add_command_trace(struct ufs_hba *hba,
 		unsigned int tag, const char *str)
 {
 	sector_t lba = -1;
-	u8 opcode = 0;
+	u8 opcode = 0, group_id = 0;
 	u32 intr, doorbell;
 	struct ufshcd_lrb *lrbp = &hba->lrb[tag];
 	struct scsi_cmnd *cmd = lrbp->cmd;
@@ -374,13 +374,15 @@ static void ufshcd_add_command_trace(struct ufs_hba *hba,
 				lba = cmd->request->bio->bi_iter.bi_sector;
 			transfer_len = be32_to_cpu(
 				lrbp->ucd_req_ptr->sc.exp_data_transfer_len);
+			if (opcode == WRITE_10)
+				group_id = lrbp->cmd->cmnd[6];
 		}
 	}
 
 	intr = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
 	doorbell = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
 	trace_ufshcd_command(dev_name(hba->dev), str, tag,
-				doorbell, transfer_len, intr, lba, opcode);
+			doorbell, transfer_len, intr, lba, opcode, group_id);
 }
 
 static void ufshcd_print_clk_freqs(struct ufs_hba *hba)
diff --git a/include/trace/events/ufs.h b/include/trace/events/ufs.h
index 84841b3a7ffd..50654f352639 100644
--- a/include/trace/events/ufs.h
+++ b/include/trace/events/ufs.h
@@ -11,6 +11,15 @@
 
 #include <linux/tracepoint.h>
 
+#define str_opcode(opcode)						\
+	__print_symbolic(opcode,					\
+		{ WRITE_16,		"WRITE_16" },			\
+		{ WRITE_10,		"WRITE_10" },			\
+		{ READ_16,		"READ_16" },			\
+		{ READ_10,		"READ_10" },			\
+		{ SYNCHRONIZE_CACHE,	"SYNC" },			\
+		{ UNMAP,		"UNMAP" })
+
 #define UFS_LINK_STATES			\
 	EM(UIC_LINK_OFF_STATE)		\
 	EM(UIC_LINK_ACTIVE_STATE)	\
@@ -215,9 +224,10 @@ DEFINE_EVENT(ufshcd_template, ufshcd_init,
 TRACE_EVENT(ufshcd_command,
 	TP_PROTO(const char *dev_name, const char *str, unsigned int tag,
 			u32 doorbell, int transfer_len, u32 intr, u64 lba,
-			u8 opcode),
+			u8 opcode, u8 group_id),
 
-	TP_ARGS(dev_name, str, tag, doorbell, transfer_len, intr, lba, opcode),
+	TP_ARGS(dev_name, str, tag, doorbell, transfer_len,
+				intr, lba, opcode, group_id),
 
 	TP_STRUCT__entry(
 		__string(dev_name, dev_name)
@@ -228,6 +238,7 @@ TRACE_EVENT(ufshcd_command,
 		__field(u32, intr)
 		__field(u64, lba)
 		__field(u8, opcode)
+		__field(u8, group_id)
 	),
 
 	TP_fast_assign(
@@ -239,13 +250,15 @@ TRACE_EVENT(ufshcd_command,
 		__entry->intr = intr;
 		__entry->lba = lba;
 		__entry->opcode = opcode;
+		__entry->group_id = group_id;
 	),
 
 	TP_printk(
-		"%s: %s: tag: %u, DB: 0x%x, size: %d, IS: %u, LBA: %llu, opcode: 0x%x",
+		"%s: %s: tag: %u, DB: 0x%x, size: %d, IS: %u, LBA: %llu, opcode: 0x%x (%s), group_id: 0x%x",
 		__get_str(str), __get_str(dev_name), __entry->tag,
 		__entry->doorbell, __entry->transfer_len,
-		__entry->intr, __entry->lba, (u32)__entry->opcode
+		__entry->intr, __entry->lba, (u32)__entry->opcode,
+		str_opcode(__entry->opcode), (u32)__entry->group_id
 	)
 );
 
-- 
2.29.0.rc1.297.gfa9743e501-goog

[PATCH v4 5/5] scsi: ufs: fix clkgating on/off correctly

[Jaegeuk Kim]

The below call stack prevents clk_gating at every IO completion.
We can remove the condition, ufshcd_any_tag_in_use(), since clkgating_work
will check it again.

ufshcd_complete_requests(struct ufs_hba *hba)
  ufshcd_transfer_req_compl()
    __ufshcd_transfer_req_compl()
      __ufshcd_release(hba)
        if (ufshcd_any_tag_in_use() == 1)
           return;
  ufshcd_tmc_handler(hba);
    blk_mq_tagset_busy_iter();

Note that, this still requires a work to deal with a potential racy condition
when user sets clkgating.delay_ms to very small value. That can cause preventing
clkgating by the check of ufshcd_any_tag_in_use() in gate_work.

Fixes: 7252a3603015 ("scsi: ufs: Avoid busy-waiting by eliminating tag conflicts")
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index b8a54d09e750..86c8dee01ca9 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1746,7 +1746,7 @@ static void __ufshcd_release(struct ufs_hba *hba)
 
 	if (hba->clk_gating.active_reqs || hba->clk_gating.is_suspended ||
 	    hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL ||
-	    ufshcd_any_tag_in_use(hba) || hba->outstanding_tasks ||
+	    hba->outstanding_tasks ||
 	    hba->active_uic_cmd || hba->uic_async_done ||
 	    hba->clk_gating.state == CLKS_OFF)
 		return;
-- 
2.29.0.rc1.297.gfa9743e501-goog

Re: [PATCH v4 1/5] scsi: ufs: atomic update for clkgating_enable

[Can Guo]

On 2020-10-27 03:51, Jaegeuk Kim wrote:
> From: Jaegeuk Kim <jaegeuk@google.com>
> 
> When giving a stress test which enables/disables clkgating, we hit 
> device
> timeout sometimes. This patch avoids subtle racy condition to address 
> it.
> 
> Note that, this requires a patch to address the device stuck by 
> REQ_CLKS_OFF in
> __ufshcd_release().
> 
> The fix is "scsi: ufs: avoid to call REQ_CLKS_OFF to CLKS_OFF".

Why don't you just squash the fix into this one?

Thanks,

Can Guo.

> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
> ---
>  drivers/scsi/ufs/ufshcd.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index cc8d5f0c3fdc..6c9269bffcbd 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1808,19 +1808,19 @@ static ssize_t
> ufshcd_clkgate_enable_store(struct device *dev,
>  		return -EINVAL;
> 
>  	value = !!value;
> +
> +	spin_lock_irqsave(hba->host->host_lock, flags);
>  	if (value == hba->clk_gating.is_enabled)
>  		goto out;
> 
> -	if (value) {
> -		ufshcd_release(hba);
> -	} else {
> -		spin_lock_irqsave(hba->host->host_lock, flags);
> +	if (value)
> +		__ufshcd_release(hba);
> +	else
>  		hba->clk_gating.active_reqs++;
> -		spin_unlock_irqrestore(hba->host->host_lock, flags);
> -	}
> 
>  	hba->clk_gating.is_enabled = value;
>  out:
> +	spin_unlock_irqrestore(hba->host->host_lock, flags);
>  	return count;
>  }

Re: [PATCH v4 5/5] scsi: ufs: fix clkgating on/off correctly

[Can Guo]

On 2020-10-27 03:51, Jaegeuk Kim wrote:
> The below call stack prevents clk_gating at every IO completion.
> We can remove the condition, ufshcd_any_tag_in_use(), since 
> clkgating_work
> will check it again.
> 
> ufshcd_complete_requests(struct ufs_hba *hba)
>   ufshcd_transfer_req_compl()
>     __ufshcd_transfer_req_compl()
>       __ufshcd_release(hba)
>         if (ufshcd_any_tag_in_use() == 1)
>            return;
>   ufshcd_tmc_handler(hba);
>     blk_mq_tagset_busy_iter();
> 
> Note that, this still requires a work to deal with a potential racy 
> condition
> when user sets clkgating.delay_ms to very small value. That can cause 
> preventing
> clkgating by the check of ufshcd_any_tag_in_use() in gate_work.
> 
> Fixes: 7252a3603015 ("scsi: ufs: Avoid busy-waiting by eliminating tag
> conflicts")
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>

Reviewed-by: Can Guo <cang@codeaurora.org>

> ---
>  drivers/scsi/ufs/ufshcd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index b8a54d09e750..86c8dee01ca9 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1746,7 +1746,7 @@ static void __ufshcd_release(struct ufs_hba *hba)
> 
>  	if (hba->clk_gating.active_reqs || hba->clk_gating.is_suspended ||
>  	    hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL ||
> -	    ufshcd_any_tag_in_use(hba) || hba->outstanding_tasks ||
> +	    hba->outstanding_tasks ||
>  	    hba->active_uic_cmd || hba->uic_async_done ||
>  	    hba->clk_gating.state == CLKS_OFF)
>  		return;

Re: [PATCH v4 1/5] scsi: ufs: atomic update for clkgating_enable

[Jaegeuk Kim]

On 10/27, Can Guo wrote:
> On 2020-10-27 03:51, Jaegeuk Kim wrote:
> > From: Jaegeuk Kim <jaegeuk@google.com>
> > 
> > When giving a stress test which enables/disables clkgating, we hit
> > device
> > timeout sometimes. This patch avoids subtle racy condition to address
> > it.
> > 
> > Note that, this requires a patch to address the device stuck by
> > REQ_CLKS_OFF in
> > __ufshcd_release().
> > 
> > The fix is "scsi: ufs: avoid to call REQ_CLKS_OFF to CLKS_OFF".
> 
> Why don't you just squash the fix into this one?

I'm seeing this patch just revealed that problem.

> 
> Thanks,
> 
> Can Guo.
> 
> > 
> > Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
> > ---
> >  drivers/scsi/ufs/ufshcd.c | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index cc8d5f0c3fdc..6c9269bffcbd 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -1808,19 +1808,19 @@ static ssize_t
> > ufshcd_clkgate_enable_store(struct device *dev,
> >  		return -EINVAL;
> > 
> >  	value = !!value;
> > +
> > +	spin_lock_irqsave(hba->host->host_lock, flags);
> >  	if (value == hba->clk_gating.is_enabled)
> >  		goto out;
> > 
> > -	if (value) {
> > -		ufshcd_release(hba);
> > -	} else {
> > -		spin_lock_irqsave(hba->host->host_lock, flags);
> > +	if (value)
> > +		__ufshcd_release(hba);
> > +	else
> >  		hba->clk_gating.active_reqs++;
> > -		spin_unlock_irqrestore(hba->host->host_lock, flags);
> > -	}
> > 
> >  	hba->clk_gating.is_enabled = value;
> >  out:
> > +	spin_unlock_irqrestore(hba->host->host_lock, flags);
> >  	return count;
> >  }

Re: [PATCH v4 1/5] scsi: ufs: atomic update for clkgating_enable

[Can Guo]

On 2020-10-27 11:33, Jaegeuk Kim wrote:
> On 10/27, Can Guo wrote:
>> On 2020-10-27 03:51, Jaegeuk Kim wrote:
>> > From: Jaegeuk Kim <jaegeuk@google.com>
>> >
>> > When giving a stress test which enables/disables clkgating, we hit
>> > device
>> > timeout sometimes. This patch avoids subtle racy condition to address
>> > it.
>> >
>> > Note that, this requires a patch to address the device stuck by
>> > REQ_CLKS_OFF in
>> > __ufshcd_release().
>> >
>> > The fix is "scsi: ufs: avoid to call REQ_CLKS_OFF to CLKS_OFF".
>> 
>> Why don't you just squash the fix into this one?
> 
> I'm seeing this patch just revealed that problem.

That scenario (back to back calling of ufshcd_release()) only happens
when you stress the clkgate_enable sysfs node, so let's keep the fix
as one to make things simple. What do you think?

Thanks,

Can Guo.

> 
>> 
>> Thanks,
>> 
>> Can Guo.
>> 
>> >
>> > Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
>> > ---
>> >  drivers/scsi/ufs/ufshcd.c | 12 ++++++------
>> >  1 file changed, 6 insertions(+), 6 deletions(-)
>> >
>> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> > index cc8d5f0c3fdc..6c9269bffcbd 100644
>> > --- a/drivers/scsi/ufs/ufshcd.c
>> > +++ b/drivers/scsi/ufs/ufshcd.c
>> > @@ -1808,19 +1808,19 @@ static ssize_t
>> > ufshcd_clkgate_enable_store(struct device *dev,
>> >  		return -EINVAL;
>> >
>> >  	value = !!value;
>> > +
>> > +	spin_lock_irqsave(hba->host->host_lock, flags);
>> >  	if (value == hba->clk_gating.is_enabled)
>> >  		goto out;
>> >
>> > -	if (value) {
>> > -		ufshcd_release(hba);
>> > -	} else {
>> > -		spin_lock_irqsave(hba->host->host_lock, flags);
>> > +	if (value)
>> > +		__ufshcd_release(hba);
>> > +	else
>> >  		hba->clk_gating.active_reqs++;
>> > -		spin_unlock_irqrestore(hba->host->host_lock, flags);
>> > -	}
>> >
>> >  	hba->clk_gating.is_enabled = value;
>> >  out:
>> > +	spin_unlock_irqrestore(hba->host->host_lock, flags);
>> >  	return count;
>> >  }

Re: [PATCH v4 1/5] scsi: ufs: atomic update for clkgating_enable

[Jaegeuk Kim]

On 10/27, Can Guo wrote:
> On 2020-10-27 11:33, Jaegeuk Kim wrote:
> > On 10/27, Can Guo wrote:
> > > On 2020-10-27 03:51, Jaegeuk Kim wrote:
> > > > From: Jaegeuk Kim <jaegeuk@google.com>
> > > >
> > > > When giving a stress test which enables/disables clkgating, we hit
> > > > device
> > > > timeout sometimes. This patch avoids subtle racy condition to address
> > > > it.
> > > >
> > > > Note that, this requires a patch to address the device stuck by
> > > > REQ_CLKS_OFF in
> > > > __ufshcd_release().
> > > >
> > > > The fix is "scsi: ufs: avoid to call REQ_CLKS_OFF to CLKS_OFF".
> > > 
> > > Why don't you just squash the fix into this one?
> > 
> > I'm seeing this patch just revealed that problem.
> 
> That scenario (back to back calling of ufshcd_release()) only happens
> when you stress the clkgate_enable sysfs node, so let's keep the fix
> as one to make things simple. What do you think?

If we don't have this patch, do you think this issue won't happen at all?

> 
> Thanks,
> 
> Can Guo.
> 
> > 
> > > 
> > > Thanks,
> > > 
> > > Can Guo.
> > > 
> > > >
> > > > Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
> > > > ---
> > > >  drivers/scsi/ufs/ufshcd.c | 12 ++++++------
> > > >  1 file changed, 6 insertions(+), 6 deletions(-)
> > > >
> > > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > > > index cc8d5f0c3fdc..6c9269bffcbd 100644
> > > > --- a/drivers/scsi/ufs/ufshcd.c
> > > > +++ b/drivers/scsi/ufs/ufshcd.c
> > > > @@ -1808,19 +1808,19 @@ static ssize_t
> > > > ufshcd_clkgate_enable_store(struct device *dev,
> > > >  		return -EINVAL;
> > > >
> > > >  	value = !!value;
> > > > +
> > > > +	spin_lock_irqsave(hba->host->host_lock, flags);
> > > >  	if (value == hba->clk_gating.is_enabled)
> > > >  		goto out;
> > > >
> > > > -	if (value) {
> > > > -		ufshcd_release(hba);
> > > > -	} else {
> > > > -		spin_lock_irqsave(hba->host->host_lock, flags);
> > > > +	if (value)
> > > > +		__ufshcd_release(hba);
> > > > +	else
> > > >  		hba->clk_gating.active_reqs++;
> > > > -		spin_unlock_irqrestore(hba->host->host_lock, flags);
> > > > -	}
> > > >
> > > >  	hba->clk_gating.is_enabled = value;
> > > >  out:
> > > > +	spin_unlock_irqrestore(hba->host->host_lock, flags);
> > > >  	return count;
> > > >  }

Re: [PATCH v4 1/5] scsi: ufs: atomic update for clkgating_enable

[Can Guo]

On 2020-10-29 03:43, Jaegeuk Kim wrote:
> On 10/27, Can Guo wrote:
>> On 2020-10-27 11:33, Jaegeuk Kim wrote:
>> > On 10/27, Can Guo wrote:
>> > > On 2020-10-27 03:51, Jaegeuk Kim wrote:
>> > > > From: Jaegeuk Kim <jaegeuk@google.com>
>> > > >
>> > > > When giving a stress test which enables/disables clkgating, we hit
>> > > > device
>> > > > timeout sometimes. This patch avoids subtle racy condition to address
>> > > > it.
>> > > >
>> > > > Note that, this requires a patch to address the device stuck by
>> > > > REQ_CLKS_OFF in
>> > > > __ufshcd_release().
>> > > >
>> > > > The fix is "scsi: ufs: avoid to call REQ_CLKS_OFF to CLKS_OFF".
>> > >
>> > > Why don't you just squash the fix into this one?
>> >
>> > I'm seeing this patch just revealed that problem.
>> 
>> That scenario (back to back calling of ufshcd_release()) only happens
>> when you stress the clkgate_enable sysfs node, so let's keep the fix
>> as one to make things simple. What do you think?
> 
> If we don't have this patch, do you think this issue won't happen at 
> all?
> 

At least I've never seen this scenario these years, otherwise I would 
have
put up a fix.

Thanks,

Can Guo.

>> 
>> Thanks,
>> 
>> Can Guo.
>> 
>> >
>> > >
>> > > Thanks,
>> > >
>> > > Can Guo.
>> > >
>> > > >
>> > > > Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
>> > > > ---
>> > > >  drivers/scsi/ufs/ufshcd.c | 12 ++++++------
>> > > >  1 file changed, 6 insertions(+), 6 deletions(-)
>> > > >
>> > > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> > > > index cc8d5f0c3fdc..6c9269bffcbd 100644
>> > > > --- a/drivers/scsi/ufs/ufshcd.c
>> > > > +++ b/drivers/scsi/ufs/ufshcd.c
>> > > > @@ -1808,19 +1808,19 @@ static ssize_t
>> > > > ufshcd_clkgate_enable_store(struct device *dev,
>> > > >  		return -EINVAL;
>> > > >
>> > > >  	value = !!value;
>> > > > +
>> > > > +	spin_lock_irqsave(hba->host->host_lock, flags);
>> > > >  	if (value == hba->clk_gating.is_enabled)
>> > > >  		goto out;
>> > > >
>> > > > -	if (value) {
>> > > > -		ufshcd_release(hba);
>> > > > -	} else {
>> > > > -		spin_lock_irqsave(hba->host->host_lock, flags);
>> > > > +	if (value)
>> > > > +		__ufshcd_release(hba);
>> > > > +	else
>> > > >  		hba->clk_gating.active_reqs++;
>> > > > -		spin_unlock_irqrestore(hba->host->host_lock, flags);
>> > > > -	}
>> > > >
>> > > >  	hba->clk_gating.is_enabled = value;
>> > > >  out:
>> > > > +	spin_unlock_irqrestore(hba->host->host_lock, flags);
>> > > >  	return count;
>> > > >  }