* [PATCH v3] ufs: core: fix lockdep warning of clk_scaling_lock
@ 2022-07-26 9:14 peter.wang
2022-07-26 15:05 ` Greg KH
0 siblings, 1 reply; 3+ messages in thread
From: peter.wang @ 2022-07-26 9:14 UTC (permalink / raw)
To: stanley.chu, linux-scsi, martin.petersen, avri.altman,
alim.akhtar, jejb
Cc: wsd_upstream, linux-mediatek, peter.wang, chun-hung.wu,
alice.chao, cc.chou, chaotian.jing, jiajie.hao, powen.kao,
qilin.tan, lin.gui, stable
From: Peter Wang <peter.wang@mediatek.com>
There have a lockdep warning like below in current flow.
kworker/u16:0: Possible unsafe locking scenario:
kworker/u16:0: CPU0 CPU1
kworker/u16:0: ---- ----
kworker/u16:0: lock(&hba->clk_scaling_lock);
kworker/u16:0: lock(&hba->dev_cmd.lock);
kworker/u16:0: lock(&hba->clk_scaling_lock);
kworker/u16:0: lock(&hba->dev_cmd.lock);
kworker/u16:0:
Before this patch clk_scaling_lock was held in reader mode during the ufshcd_wb_toggle() call.
With this patch applied clk_scaling_lock is not held while ufshcd_wb_toggle() is called.
This is safe because ufshcd_wb_toggle will held clk_scaling_lock in reader mode "again" in flow
ufshcd_wb_toggle -> __ufshcd_wb_toggle -> ufshcd_query_flag_retry -> ufshcd_query_flag ->
ufshcd_exec_dev_cmd -> down_read(&hba->clk_scaling_lock);
The protect should enough and make sure clock is not change while send command.
ufshcd_wb_toggle can protected by hba->clk_scaling.is_allowed to make sure
ufshcd_devfreq_scale function not run concurrently.
Fixes: 0e9d4ca43ba8 ("scsi: ufs: Protect some contexts from unexpected clock scaling")
Signed-off-by: Peter Wang <peter.wang@mediatek.com>
---
drivers/ufs/core/ufshcd.c | 27 ++++++++++++++++-----------
1 file changed, 16 insertions(+), 11 deletions(-)
diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index c7b337480e3e..aa57126fdb49 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -272,6 +272,7 @@ static void ufshcd_wb_toggle_flush_during_h8(struct ufs_hba *hba, bool set);
static inline void ufshcd_wb_toggle_flush(struct ufs_hba *hba, bool enable);
static void ufshcd_hba_vreg_set_lpm(struct ufs_hba *hba);
static void ufshcd_hba_vreg_set_hpm(struct ufs_hba *hba);
+static void ufshcd_clk_scaling_allow(struct ufs_hba *hba, bool allow);
static inline void ufshcd_enable_irq(struct ufs_hba *hba)
{
@@ -1249,12 +1250,10 @@ static int ufshcd_clock_scaling_prepare(struct ufs_hba *hba)
return ret;
}
-static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, bool writelock)
+static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba)
{
- if (writelock)
- up_write(&hba->clk_scaling_lock);
- else
- up_read(&hba->clk_scaling_lock);
+ up_write(&hba->clk_scaling_lock);
+
ufshcd_scsi_unblock_requests(hba);
ufshcd_release(hba);
}
@@ -1271,7 +1270,7 @@ static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, bool writelock)
static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
{
int ret = 0;
- bool is_writelock = true;
+ bool wb_toggle = false;
ret = ufshcd_clock_scaling_prepare(hba);
if (ret)
@@ -1300,13 +1299,19 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
}
}
- /* Enable Write Booster if we have scaled up else disable it */
- downgrade_write(&hba->clk_scaling_lock);
- is_writelock = false;
- ufshcd_wb_toggle(hba, scale_up);
+ /* Disable clk_scaling until ufshcd_wb_toggle finish */
+ hba->clk_scaling.is_allowed = false;
+ wb_toggle = true;
out_unprepare:
- ufshcd_clock_scaling_unprepare(hba, is_writelock);
+ ufshcd_clock_scaling_unprepare(hba);
+
+ /* Enable Write Booster if we have scaled up else disable it */
+ if (wb_toggle) {
+ ufshcd_wb_toggle(hba, scale_up);
+ ufshcd_clk_scaling_allow(hba, true);
+ }
+
return ret;
}
--
2.18.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH v3] ufs: core: fix lockdep warning of clk_scaling_lock
2022-07-26 9:14 [PATCH v3] ufs: core: fix lockdep warning of clk_scaling_lock peter.wang
@ 2022-07-26 15:05 ` Greg KH
2022-07-27 3:08 ` Peter Wang
0 siblings, 1 reply; 3+ messages in thread
From: Greg KH @ 2022-07-26 15:05 UTC (permalink / raw)
To: peter.wang
Cc: stanley.chu, linux-scsi, martin.petersen, avri.altman,
alim.akhtar, jejb, wsd_upstream, linux-mediatek, chun-hung.wu,
alice.chao, cc.chou, chaotian.jing, jiajie.hao, powen.kao,
qilin.tan, lin.gui, stable
On Tue, Jul 26, 2022 at 05:14:33PM +0800, peter.wang@mediatek.com wrote:
> From: Peter Wang <peter.wang@mediatek.com>
>
> There have a lockdep warning like below in current flow.
> kworker/u16:0: Possible unsafe locking scenario:
>
> kworker/u16:0: CPU0 CPU1
> kworker/u16:0: ---- ----
> kworker/u16:0: lock(&hba->clk_scaling_lock);
> kworker/u16:0: lock(&hba->dev_cmd.lock);
> kworker/u16:0: lock(&hba->clk_scaling_lock);
> kworker/u16:0: lock(&hba->dev_cmd.lock);
> kworker/u16:0:
>
> Before this patch clk_scaling_lock was held in reader mode during the ufshcd_wb_toggle() call.
> With this patch applied clk_scaling_lock is not held while ufshcd_wb_toggle() is called.
>
> This is safe because ufshcd_wb_toggle will held clk_scaling_lock in reader mode "again" in flow
> ufshcd_wb_toggle -> __ufshcd_wb_toggle -> ufshcd_query_flag_retry -> ufshcd_query_flag ->
> ufshcd_exec_dev_cmd -> down_read(&hba->clk_scaling_lock);
> The protect should enough and make sure clock is not change while send command.
>
> ufshcd_wb_toggle can protected by hba->clk_scaling.is_allowed to make sure
> ufshcd_devfreq_scale function not run concurrently.
>
> Fixes: 0e9d4ca43ba8 ("scsi: ufs: Protect some contexts from unexpected clock scaling")
> Signed-off-by: Peter Wang <peter.wang@mediatek.com>
> ---
> drivers/ufs/core/ufshcd.c | 27 ++++++++++++++++-----------
> 1 file changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index c7b337480e3e..aa57126fdb49 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -272,6 +272,7 @@ static void ufshcd_wb_toggle_flush_during_h8(struct ufs_hba *hba, bool set);
> static inline void ufshcd_wb_toggle_flush(struct ufs_hba *hba, bool enable);
> static void ufshcd_hba_vreg_set_lpm(struct ufs_hba *hba);
> static void ufshcd_hba_vreg_set_hpm(struct ufs_hba *hba);
> +static void ufshcd_clk_scaling_allow(struct ufs_hba *hba, bool allow);
>
> static inline void ufshcd_enable_irq(struct ufs_hba *hba)
> {
> @@ -1249,12 +1250,10 @@ static int ufshcd_clock_scaling_prepare(struct ufs_hba *hba)
> return ret;
> }
>
> -static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, bool writelock)
> +static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba)
> {
> - if (writelock)
> - up_write(&hba->clk_scaling_lock);
> - else
> - up_read(&hba->clk_scaling_lock);
> + up_write(&hba->clk_scaling_lock);
> +
> ufshcd_scsi_unblock_requests(hba);
> ufshcd_release(hba);
> }
> @@ -1271,7 +1270,7 @@ static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, bool writelock)
> static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
> {
> int ret = 0;
> - bool is_writelock = true;
> + bool wb_toggle = false;
>
> ret = ufshcd_clock_scaling_prepare(hba);
> if (ret)
> @@ -1300,13 +1299,19 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
> }
> }
>
> - /* Enable Write Booster if we have scaled up else disable it */
> - downgrade_write(&hba->clk_scaling_lock);
> - is_writelock = false;
> - ufshcd_wb_toggle(hba, scale_up);
> + /* Disable clk_scaling until ufshcd_wb_toggle finish */
> + hba->clk_scaling.is_allowed = false;
> + wb_toggle = true;
>
> out_unprepare:
> - ufshcd_clock_scaling_unprepare(hba, is_writelock);
> + ufshcd_clock_scaling_unprepare(hba);
> +
> + /* Enable Write Booster if we have scaled up else disable it */
> + if (wb_toggle) {
> + ufshcd_wb_toggle(hba, scale_up);
> + ufshcd_clk_scaling_allow(hba, true);
> + }
> +
> return ret;
> }
>
> --
> 2.18.0
>
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v3] ufs: core: fix lockdep warning of clk_scaling_lock
2022-07-26 15:05 ` Greg KH
@ 2022-07-27 3:08 ` Peter Wang
0 siblings, 0 replies; 3+ messages in thread
From: Peter Wang @ 2022-07-27 3:08 UTC (permalink / raw)
To: Greg KH
Cc: stanley.chu, linux-scsi, martin.petersen, avri.altman,
alim.akhtar, jejb, wsd_upstream, linux-mediatek, chun-hung.wu,
alice.chao, cc.chou, chaotian.jing, jiajie.hao, powen.kao,
qilin.tan, lin.gui, stable
On 7/26/22 11:05 PM, Greg KH wrote:
> On Tue, Jul 26, 2022 at 05:14:33PM +0800, peter.wang@mediatek.com wrote:
>> From: Peter Wang <peter.wang@mediatek.com>
>>
>> There have a lockdep warning like below in current flow.
>> kworker/u16:0: Possible unsafe locking scenario:
>>
>> kworker/u16:0: CPU0 CPU1
>> kworker/u16:0: ---- ----
>> kworker/u16:0: lock(&hba->clk_scaling_lock);
>> kworker/u16:0: lock(&hba->dev_cmd.lock);
>> kworker/u16:0: lock(&hba->clk_scaling_lock);
>> kworker/u16:0: lock(&hba->dev_cmd.lock);
>> kworker/u16:0:
>>
>> Before this patch clk_scaling_lock was held in reader mode during the ufshcd_wb_toggle() call.
>> With this patch applied clk_scaling_lock is not held while ufshcd_wb_toggle() is called.
>>
>> This is safe because ufshcd_wb_toggle will held clk_scaling_lock in reader mode "again" in flow
>> ufshcd_wb_toggle -> __ufshcd_wb_toggle -> ufshcd_query_flag_retry -> ufshcd_query_flag ->
>> ufshcd_exec_dev_cmd -> down_read(&hba->clk_scaling_lock);
>> The protect should enough and make sure clock is not change while send command.
>>
>> ufshcd_wb_toggle can protected by hba->clk_scaling.is_allowed to make sure
>> ufshcd_devfreq_scale function not run concurrently.
>>
>> Fixes: 0e9d4ca43ba8 ("scsi: ufs: Protect some contexts from unexpected clock scaling")
>> Signed-off-by: Peter Wang <peter.wang@mediatek.com>
>> ---
>> drivers/ufs/core/ufshcd.c | 27 ++++++++++++++++-----------
>> 1 file changed, 16 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
>> index c7b337480e3e..aa57126fdb49 100644
>> --- a/drivers/ufs/core/ufshcd.c
>> +++ b/drivers/ufs/core/ufshcd.c
>> @@ -272,6 +272,7 @@ static void ufshcd_wb_toggle_flush_during_h8(struct ufs_hba *hba, bool set);
>> static inline void ufshcd_wb_toggle_flush(struct ufs_hba *hba, bool enable);
>> static void ufshcd_hba_vreg_set_lpm(struct ufs_hba *hba);
>> static void ufshcd_hba_vreg_set_hpm(struct ufs_hba *hba);
>> +static void ufshcd_clk_scaling_allow(struct ufs_hba *hba, bool allow);
>>
>> static inline void ufshcd_enable_irq(struct ufs_hba *hba)
>> {
>> @@ -1249,12 +1250,10 @@ static int ufshcd_clock_scaling_prepare(struct ufs_hba *hba)
>> return ret;
>> }
>>
>> -static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, bool writelock)
>> +static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba)
>> {
>> - if (writelock)
>> - up_write(&hba->clk_scaling_lock);
>> - else
>> - up_read(&hba->clk_scaling_lock);
>> + up_write(&hba->clk_scaling_lock);
>> +
>> ufshcd_scsi_unblock_requests(hba);
>> ufshcd_release(hba);
>> }
>> @@ -1271,7 +1270,7 @@ static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba, bool writelock)
>> static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
>> {
>> int ret = 0;
>> - bool is_writelock = true;
>> + bool wb_toggle = false;
>>
>> ret = ufshcd_clock_scaling_prepare(hba);
>> if (ret)
>> @@ -1300,13 +1299,19 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
>> }
>> }
>>
>> - /* Enable Write Booster if we have scaled up else disable it */
>> - downgrade_write(&hba->clk_scaling_lock);
>> - is_writelock = false;
>> - ufshcd_wb_toggle(hba, scale_up);
>> + /* Disable clk_scaling until ufshcd_wb_toggle finish */
>> + hba->clk_scaling.is_allowed = false;
>> + wb_toggle = true;
>>
>> out_unprepare:
>> - ufshcd_clock_scaling_unprepare(hba, is_writelock);
>> + ufshcd_clock_scaling_unprepare(hba);
>> +
>> + /* Enable Write Booster if we have scaled up else disable it */
>> + if (wb_toggle) {
>> + ufshcd_wb_toggle(hba, scale_up);
>> + ufshcd_clk_scaling_allow(hba, true);
>> + }
>> +
>> return ret;
>> }
>>
>> --
>> 2.18.0
>>
> <formletter>
>
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree. Please read:
> https://urldefense.com/v3/__https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html__;!!CTRNKA9wMg0ARbw!24V8xNPFu0-WdpS3FH6jpUbnVGjhGphz8M0EYnzuRQWgnNx5qPBSLSwEtdHFyz63fw$
> for how to do this properly.
Hi Greg,
Thank you for remind.
Will use correct way next version
Thanks
Peter
>
> </formletter>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-07-26 9:14 [PATCH v3] ufs: core: fix lockdep warning of clk_scaling_lock peter.wang
2022-07-26 15:05 ` Greg KH
2022-07-27 3:08 ` Peter Wang
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