[PATCH 0/2] Untie the host lock entanglement - part 2

[PATCH 0/2] Untie the host lock entanglement - part 2

[Avri Altman]

Here is the 2nd part in the sequel, watering down the scsi host lock
usage in the ufs driver. This work is motivated by a comment made by
Bart [1], of the abuse of the scsi host lock in the ufs driver.  Its
Precursor [2] removed the host lock around some of the host register
accesses.

This part replace the scsi host lock by dedicated locks serializing
access to the clock gating and clock scaling members.


[1] https://lore.kernel.org/linux-scsi/0b031b8f-c07c-42ef-af93-7336439d3c37@acm.org/
[2] https://lore.kernel.org/linux-scsi/20241024075033.562562-1-avri.altman@wdc.com/

Avri Altman (2):
  scsi: ufs: core: Introduce a new clock_gating lock
  scsi: ufs: core: Introduce a new clock_scaling lock

 drivers/ufs/core/ufshcd.c | 92 ++++++++++++++++++++-------------------
 include/ufs/ufshcd.h      |  4 ++
 2 files changed, 52 insertions(+), 44 deletions(-)

-- 
2.25.1

[PATCH 1/2] scsi: ufs: core: Introduce a new clock_gating lock

[Avri Altman]

Introduce a new clock gating lock to seriliaze access to the clock
gating members instead of the host_lock.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/ufs/core/ufshcd.c | 44 ++++++++++++++++++++-------------------
 include/ufs/ufshcd.h      |  2 ++
 2 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 099373a25017..b7c7a7dd327f 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -1817,13 +1817,13 @@ static void ufshcd_ungate_work(struct work_struct *work)
 
 	cancel_delayed_work_sync(&hba->clk_gating.gate_work);
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&hba->clk_gating.lock, flags);
 	if (hba->clk_gating.state == CLKS_ON) {
-		spin_unlock_irqrestore(hba->host->host_lock, flags);
+		spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
 		return;
 	}
 
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
 	ufshcd_hba_vreg_set_hpm(hba);
 	ufshcd_setup_clocks(hba, true);
 
@@ -1858,7 +1858,7 @@ void ufshcd_hold(struct ufs_hba *hba)
 	if (!ufshcd_is_clkgating_allowed(hba) ||
 	    !hba->clk_gating.is_initialized)
 		return;
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&hba->clk_gating.lock, flags);
 	hba->clk_gating.active_reqs++;
 
 start:
@@ -1874,11 +1874,11 @@ void ufshcd_hold(struct ufs_hba *hba)
 		 */
 		if (ufshcd_can_hibern8_during_gating(hba) &&
 		    ufshcd_is_link_hibern8(hba)) {
-			spin_unlock_irqrestore(hba->host->host_lock, flags);
+			spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
 			flush_result = flush_work(&hba->clk_gating.ungate_work);
 			if (hba->clk_gating.is_suspended && !flush_result)
 				return;
-			spin_lock_irqsave(hba->host->host_lock, flags);
+			spin_lock_irqsave(&hba->clk_gating.lock, flags);
 			goto start;
 		}
 		break;
@@ -1907,17 +1907,17 @@ void ufshcd_hold(struct ufs_hba *hba)
 		 */
 		fallthrough;
 	case REQ_CLKS_ON:
-		spin_unlock_irqrestore(hba->host->host_lock, flags);
+		spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
 		flush_work(&hba->clk_gating.ungate_work);
 		/* Make sure state is CLKS_ON before returning */
-		spin_lock_irqsave(hba->host->host_lock, flags);
+		spin_lock_irqsave(&hba->clk_gating.lock, flags);
 		goto start;
 	default:
 		dev_err(hba->dev, "%s: clk gating is in invalid state %d\n",
 				__func__, hba->clk_gating.state);
 		break;
 	}
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
 }
 EXPORT_SYMBOL_GPL(ufshcd_hold);
 
@@ -1928,7 +1928,7 @@ static void ufshcd_gate_work(struct work_struct *work)
 	unsigned long flags;
 	int ret;
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&hba->clk_gating.lock, flags);
 	/*
 	 * In case you are here to cancel this work the gating state
 	 * would be marked as REQ_CLKS_ON. In this case save time by
@@ -1946,7 +1946,7 @@ static void ufshcd_gate_work(struct work_struct *work)
 	if (ufshcd_is_ufs_dev_busy(hba) || hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL)
 		goto rel_lock;
 
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
 
 	/* put the link into hibern8 mode before turning off clocks */
 	if (ufshcd_can_hibern8_during_gating(hba)) {
@@ -1977,14 +1977,14 @@ static void ufshcd_gate_work(struct work_struct *work)
 	 * prevent from doing cancel work multiple times when there are
 	 * new requests arriving before the current cancel work is done.
 	 */
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&hba->clk_gating.lock, flags);
 	if (hba->clk_gating.state == REQ_CLKS_OFF) {
 		hba->clk_gating.state = CLKS_OFF;
 		trace_ufshcd_clk_gating(dev_name(hba->dev),
 					hba->clk_gating.state);
 	}
 rel_lock:
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
 out:
 	return;
 }
@@ -2015,9 +2015,9 @@ void ufshcd_release(struct ufs_hba *hba)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&hba->clk_gating.lock, flags);
 	__ufshcd_release(hba);
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
 }
 EXPORT_SYMBOL_GPL(ufshcd_release);
 
@@ -2034,9 +2034,9 @@ void ufshcd_clkgate_delay_set(struct device *dev, unsigned long value)
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 	unsigned long flags;
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&hba->clk_gating.lock, flags);
 	hba->clk_gating.delay_ms = value;
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
 }
 EXPORT_SYMBOL_GPL(ufshcd_clkgate_delay_set);
 
@@ -2072,7 +2072,7 @@ static ssize_t ufshcd_clkgate_enable_store(struct device *dev,
 
 	value = !!value;
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&hba->clk_gating.lock, flags);
 	if (value == hba->clk_gating.is_enabled)
 		goto out;
 
@@ -2083,7 +2083,7 @@ static ssize_t ufshcd_clkgate_enable_store(struct device *dev,
 
 	hba->clk_gating.is_enabled = value;
 out:
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
 	return count;
 }
 
@@ -2125,6 +2125,8 @@ static void ufshcd_init_clk_gating(struct ufs_hba *hba)
 	INIT_DELAYED_WORK(&hba->clk_gating.gate_work, ufshcd_gate_work);
 	INIT_WORK(&hba->clk_gating.ungate_work, ufshcd_ungate_work);
 
+	spin_lock_init(&hba->clk_gating.lock);
+
 	hba->clk_gating.clk_gating_workq = alloc_ordered_workqueue(
 		"ufs_clk_gating_%d", WQ_MEM_RECLAIM | WQ_HIGHPRI,
 		hba->host->host_no);
@@ -9173,11 +9175,11 @@ static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on)
 				clk_disable_unprepare(clki->clk);
 		}
 	} else if (!ret && on) {
-		spin_lock_irqsave(hba->host->host_lock, flags);
+		spin_lock_irqsave(&hba->clk_gating.lock, flags);
 		hba->clk_gating.state = CLKS_ON;
 		trace_ufshcd_clk_gating(dev_name(hba->dev),
 					hba->clk_gating.state);
-		spin_unlock_irqrestore(hba->host->host_lock, flags);
+		spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
 	}
 
 	if (clk_state_changed)
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index 9ea2a7411bb5..52c822fe2944 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -413,6 +413,7 @@ enum clk_gating_state {
  * @active_reqs: number of requests that are pending and should be waited for
  * completion before gating clocks.
  * @clk_gating_workq: workqueue for clock gating work.
+ * @lock: serielize access to the clk_gating members
  */
 struct ufs_clk_gating {
 	struct delayed_work gate_work;
@@ -426,6 +427,7 @@ struct ufs_clk_gating {
 	bool is_initialized;
 	int active_reqs;
 	struct workqueue_struct *clk_gating_workq;
+	spinlock_t lock;
 };
 
 /**
-- 
2.25.1

Re: [PATCH 1/2] scsi: ufs: core: Introduce a new clock_gating lock

[Bart Van Assche]

On 10/27/24 1:25 AM, Avri Altman wrote:
> Introduce a new clock gating lock to seriliaze access to the clock
                                        ^^^^^^^^^
                                        serialize

> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 099373a25017..b7c7a7dd327f 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -1817,13 +1817,13 @@ static void ufshcd_ungate_work(struct work_struct *work)
>   
>   	cancel_delayed_work_sync(&hba->clk_gating.gate_work);
>   
> -	spin_lock_irqsave(hba->host->host_lock, flags);
> +	spin_lock_irqsave(&hba->clk_gating.lock, flags);
>   	if (hba->clk_gating.state == CLKS_ON) {
> -		spin_unlock_irqrestore(hba->host->host_lock, flags);
> +		spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
>   		return;
>   	}
>   
> -	spin_unlock_irqrestore(hba->host->host_lock, flags);
> +	spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
>   	ufshcd_hba_vreg_set_hpm(hba);
>   	ufshcd_setup_clocks(hba, true);

This would be a great opportunity to replace the spinlock calls with
scoped_guard(), isn't it?

> @@ -1928,7 +1928,7 @@ static void ufshcd_gate_work(struct work_struct *work)
>   	unsigned long flags;
>   	int ret;
>   
> -	spin_lock_irqsave(hba->host->host_lock, flags);
> +	spin_lock_irqsave(&hba->clk_gating.lock, flags);
>   	/*
>   	 * In case you are here to cancel this work the gating state
>   	 * would be marked as REQ_CLKS_ON. In this case save time by
> @@ -1946,7 +1946,7 @@ static void ufshcd_gate_work(struct work_struct *work)
>   	if (ufshcd_is_ufs_dev_busy(hba) || hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL)
>   		goto rel_lock;
>   
> -	spin_unlock_irqrestore(hba->host->host_lock, flags);
> +	spin_unlock_irqrestore(&hba->clk_gating.lock, flags);

Same comment here: please consider using scoped_guard().

>   	/* put the link into hibern8 mode before turning off clocks */
>   	if (ufshcd_can_hibern8_during_gating(hba)) {
> @@ -1977,14 +1977,14 @@ static void ufshcd_gate_work(struct work_struct *work)
>   	 * prevent from doing cancel work multiple times when there are
>   	 * new requests arriving before the current cancel work is done.
>   	 */
> -	spin_lock_irqsave(hba->host->host_lock, flags);
> +	spin_lock_irqsave(&hba->clk_gating.lock, flags);
>   	if (hba->clk_gating.state == REQ_CLKS_OFF) {
>   		hba->clk_gating.state = CLKS_OFF;
>   		trace_ufshcd_clk_gating(dev_name(hba->dev),
>   					hba->clk_gating.state);
>   	}
>   rel_lock:
> -	spin_unlock_irqrestore(hba->host->host_lock, flags);
> +	spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
>   out:
>   	return;
>   }

ufshcd_gate_work() can be simplified by using guard() and
scoped_guard().

> @@ -2015,9 +2015,9 @@ void ufshcd_release(struct ufs_hba *hba)
>   {
>   	unsigned long flags;
>   
> -	spin_lock_irqsave(hba->host->host_lock, flags);
> +	spin_lock_irqsave(&hba->clk_gating.lock, flags);
>   	__ufshcd_release(hba);
> -	spin_unlock_irqrestore(hba->host->host_lock, flags);
> +	spin_unlock_irqrestore(&hba->clk_gating.lock, flags);

For this function and also for later changes, please use guard().

> diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
> index 9ea2a7411bb5..52c822fe2944 100644
> --- a/include/ufs/ufshcd.h
> +++ b/include/ufs/ufshcd.h
> @@ -413,6 +413,7 @@ enum clk_gating_state {
>    * @active_reqs: number of requests that are pending and should be waited for
>    * completion before gating clocks.
>    * @clk_gating_workq: workqueue for clock gating work.
> + * @lock: serielize access to the clk_gating members
              ^^^^^^^^^
              serialize

I don't think that the added comment is correct - 'lock' is used to
serialize access to some struct ufs_clk_gating members but not for
serializing access to all members. Accesses to e.g. gate_work,
ungate_work and clk_gating_workq are not serialized. Please reorder the
struct ufs_clk_gating members as follows:
- Members that are not serialized first.
- Next, 'lock'.
- Finally, the members serialized by 'lock'.

I think it is common in Linux kernel code that structure members are
organized this way.

Thanks,

Bart.

RE: [PATCH 1/2] scsi: ufs: core: Introduce a new clock_gating lock

[Avri Altman]

> 
> On 10/27/24 1:25 AM, Avri Altman wrote:
> > Introduce a new clock gating lock to seriliaze access to the clock
>                                         ^^^^^^^^^
>                                         serialize
Done.

> 
> > diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> > index 099373a25017..b7c7a7dd327f 100644
> > --- a/drivers/ufs/core/ufshcd.c
> > +++ b/drivers/ufs/core/ufshcd.c
> > @@ -1817,13 +1817,13 @@ static void ufshcd_ungate_work(struct
> > work_struct *work)
> >
> >       cancel_delayed_work_sync(&hba->clk_gating.gate_work);
> >
> > -     spin_lock_irqsave(hba->host->host_lock, flags);
> > +     spin_lock_irqsave(&hba->clk_gating.lock, flags);
> >       if (hba->clk_gating.state == CLKS_ON) {
> > -             spin_unlock_irqrestore(hba->host->host_lock, flags);
> > +             spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
> >               return;
> >       }
> >
> > -     spin_unlock_irqrestore(hba->host->host_lock, flags);
> > +     spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
> >       ufshcd_hba_vreg_set_hpm(hba);
> >       ufshcd_setup_clocks(hba, true);
> 
> This would be a great opportunity to replace the spinlock calls with
> scoped_guard(), isn't it?
Done.

> 
> > @@ -1928,7 +1928,7 @@ static void ufshcd_gate_work(struct work_struct
> *work)
> >       unsigned long flags;
> >       int ret;
> >
> > -     spin_lock_irqsave(hba->host->host_lock, flags);
> > +     spin_lock_irqsave(&hba->clk_gating.lock, flags);
> >       /*
> >        * In case you are here to cancel this work the gating state
> >        * would be marked as REQ_CLKS_ON. In this case save time by @@
> > -1946,7 +1946,7 @@ static void ufshcd_gate_work(struct work_struct
> *work)
> >       if (ufshcd_is_ufs_dev_busy(hba) || hba->ufshcd_state !=
> UFSHCD_STATE_OPERATIONAL)
> >               goto rel_lock;
> >
> > -     spin_unlock_irqrestore(hba->host->host_lock, flags);
> > +     spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
> 
> Same comment here: please consider using scoped_guard().
Done.

> 
> >       /* put the link into hibern8 mode before turning off clocks */
> >       if (ufshcd_can_hibern8_during_gating(hba)) { @@ -1977,14
> > +1977,14 @@ static void ufshcd_gate_work(struct work_struct *work)
> >        * prevent from doing cancel work multiple times when there are
> >        * new requests arriving before the current cancel work is done.
> >        */
> > -     spin_lock_irqsave(hba->host->host_lock, flags);
> > +     spin_lock_irqsave(&hba->clk_gating.lock, flags);
> >       if (hba->clk_gating.state == REQ_CLKS_OFF) {
> >               hba->clk_gating.state = CLKS_OFF;
> >               trace_ufshcd_clk_gating(dev_name(hba->dev),
> >                                       hba->clk_gating.state);
> >       }
> >   rel_lock:
> > -     spin_unlock_irqrestore(hba->host->host_lock, flags);
> > +     spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
> >   out:
> >       return;
> >   }
> 
> ufshcd_gate_work() can be simplified by using guard() and scoped_guard().
Done.

> 
> > @@ -2015,9 +2015,9 @@ void ufshcd_release(struct ufs_hba *hba)
> >   {
> >       unsigned long flags;
> >
> > -     spin_lock_irqsave(hba->host->host_lock, flags);
> > +     spin_lock_irqsave(&hba->clk_gating.lock, flags);
> >       __ufshcd_release(hba);
> > -     spin_unlock_irqrestore(hba->host->host_lock, flags);
> > +     spin_unlock_irqrestore(&hba->clk_gating.lock, flags);
> 
> For this function and also for later changes, please use guard().
Done.

> 
> > diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h index
> > 9ea2a7411bb5..52c822fe2944 100644
> > --- a/include/ufs/ufshcd.h
> > +++ b/include/ufs/ufshcd.h
> > @@ -413,6 +413,7 @@ enum clk_gating_state {
> >    * @active_reqs: number of requests that are pending and should be
> waited for
> >    * completion before gating clocks.
> >    * @clk_gating_workq: workqueue for clock gating work.
> > + * @lock: serielize access to the clk_gating members
>               ^^^^^^^^^
>               serialize
> 
> I don't think that the added comment is correct - 'lock' is used to serialize
> access to some struct ufs_clk_gating members but not for serializing access
> to all members. Accesses to e.g. gate_work, ungate_work and
> clk_gating_workq are not serialized. Please reorder the struct ufs_clk_gating
> members as follows:
> - Members that are not serialized first.
> - Next, 'lock'.
> - Finally, the members serialized by 'lock'.
> 
> I think it is common in Linux kernel code that structure members are
> organized this way.
Done.

Thanks,
Avri

> 
> Thanks,
> 
> Bart.

[PATCH 2/2] scsi: ufs: core: Introduce a new clock_scaling lock

[Avri Altman]

Introduce a new clock gating lock to seriliaze access to the clock
scaling members instead of the host_lock.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/ufs/core/ufshcd.c | 48 ++++++++++++++++++++-------------------
 include/ufs/ufshcd.h      |  2 ++
 2 files changed, 27 insertions(+), 23 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index b7c7a7dd327f..fbaee68064c9 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -1449,14 +1449,14 @@ static void ufshcd_clk_scaling_suspend_work(struct work_struct *work)
 					   clk_scaling.suspend_work);
 	unsigned long irq_flags;
 
-	spin_lock_irqsave(hba->host->host_lock, irq_flags);
+	spin_lock_irqsave(&hba->clk_scaling.lock, irq_flags);
 	if (hba->clk_scaling.active_reqs || hba->clk_scaling.is_suspended) {
-		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
+		spin_unlock_irqrestore(&hba->clk_scaling.lock, irq_flags);
 		return;
 	}
 	hba->clk_scaling.is_suspended = true;
 	hba->clk_scaling.window_start_t = 0;
-	spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
+	spin_unlock_irqrestore(&hba->clk_scaling.lock, irq_flags);
 
 	devfreq_suspend_device(hba->devfreq);
 }
@@ -1467,13 +1467,13 @@ static void ufshcd_clk_scaling_resume_work(struct work_struct *work)
 					   clk_scaling.resume_work);
 	unsigned long irq_flags;
 
-	spin_lock_irqsave(hba->host->host_lock, irq_flags);
+	spin_lock_irqsave(&hba->clk_scaling.lock, irq_flags);
 	if (!hba->clk_scaling.is_suspended) {
-		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
+		spin_unlock_irqrestore(&hba->clk_scaling.lock, irq_flags);
 		return;
 	}
 	hba->clk_scaling.is_suspended = false;
-	spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
+	spin_unlock_irqrestore(&hba->clk_scaling.lock, irq_flags);
 
 	devfreq_resume_device(hba->devfreq);
 }
@@ -1508,15 +1508,15 @@ static int ufshcd_devfreq_target(struct device *dev,
 		*freq =	(unsigned long) clk_round_rate(clki->clk, *freq);
 	}
 
-	spin_lock_irqsave(hba->host->host_lock, irq_flags);
+	spin_lock_irqsave(&hba->clk_scaling.lock, irq_flags);
 	if (ufshcd_eh_in_progress(hba)) {
-		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
+		spin_unlock_irqrestore(&hba->clk_scaling.lock, irq_flags);
 		return 0;
 	}
 
 	/* Skip scaling clock when clock scaling is suspended */
 	if (hba->clk_scaling.is_suspended) {
-		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
+		spin_unlock_irqrestore(&hba->clk_scaling.lock, irq_flags);
 		dev_warn(hba->dev, "clock scaling is suspended, skip");
 		return 0;
 	}
@@ -1525,7 +1525,7 @@ static int ufshcd_devfreq_target(struct device *dev,
 		sched_clk_scaling_suspend_work = true;
 
 	if (list_empty(clk_list)) {
-		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
+		spin_unlock_irqrestore(&hba->clk_scaling.lock, irq_flags);
 		goto out;
 	}
 
@@ -1540,11 +1540,11 @@ static int ufshcd_devfreq_target(struct device *dev,
 
 	/* Update the frequency */
 	if (!ufshcd_is_devfreq_scaling_required(hba, *freq, scale_up)) {
-		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
+		spin_unlock_irqrestore(&hba->clk_scaling.lock, irq_flags);
 		ret = 0;
 		goto out; /* no state change required */
 	}
-	spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
+	spin_unlock_irqrestore(&hba->clk_scaling.lock, irq_flags);
 
 	start = ktime_get();
 	ret = ufshcd_devfreq_scale(hba, *freq, scale_up);
@@ -1577,7 +1577,7 @@ static int ufshcd_devfreq_get_dev_status(struct device *dev,
 
 	memset(stat, 0, sizeof(*stat));
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&scaling->lock, flags);
 	curr_t = ktime_get();
 	if (!scaling->window_start_t)
 		goto start_window;
@@ -1613,7 +1613,7 @@ static int ufshcd_devfreq_get_dev_status(struct device *dev,
 		scaling->busy_start_t = 0;
 		scaling->is_busy_started = false;
 	}
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&scaling->lock, flags);
 	return 0;
 }
 
@@ -1683,13 +1683,13 @@ static void ufshcd_suspend_clkscaling(struct ufs_hba *hba)
 	cancel_work_sync(&hba->clk_scaling.suspend_work);
 	cancel_work_sync(&hba->clk_scaling.resume_work);
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&hba->clk_scaling.lock, flags);
 	if (!hba->clk_scaling.is_suspended) {
 		suspend = true;
 		hba->clk_scaling.is_suspended = true;
 		hba->clk_scaling.window_start_t = 0;
 	}
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&hba->clk_scaling.lock, flags);
 
 	if (suspend)
 		devfreq_suspend_device(hba->devfreq);
@@ -1700,12 +1700,12 @@ static void ufshcd_resume_clkscaling(struct ufs_hba *hba)
 	unsigned long flags;
 	bool resume = false;
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&hba->clk_scaling.lock, flags);
 	if (hba->clk_scaling.is_suspended) {
 		resume = true;
 		hba->clk_scaling.is_suspended = false;
 	}
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&hba->clk_scaling.lock, flags);
 
 	if (resume)
 		devfreq_resume_device(hba->devfreq);
@@ -1791,6 +1791,8 @@ static void ufshcd_init_clk_scaling(struct ufs_hba *hba)
 	INIT_WORK(&hba->clk_scaling.resume_work,
 		  ufshcd_clk_scaling_resume_work);
 
+	spin_lock_init(&hba->clk_scaling.lock);
+
 	hba->clk_scaling.workq = alloc_ordered_workqueue(
 		"ufs_clkscaling_%d", WQ_MEM_RECLAIM, hba->host->host_no);
 
@@ -2161,12 +2163,12 @@ static void ufshcd_clk_scaling_start_busy(struct ufs_hba *hba)
 	if (!ufshcd_is_clkscaling_supported(hba))
 		return;
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&hba->clk_scaling.lock, flags);
 	if (!hba->clk_scaling.active_reqs++)
 		queue_resume_work = true;
 
 	if (!hba->clk_scaling.is_enabled || hba->pm_op_in_progress) {
-		spin_unlock_irqrestore(hba->host->host_lock, flags);
+		spin_unlock_irqrestore(&hba->clk_scaling.lock, flags);
 		return;
 	}
 
@@ -2184,7 +2186,7 @@ static void ufshcd_clk_scaling_start_busy(struct ufs_hba *hba)
 		hba->clk_scaling.busy_start_t = curr_t;
 		hba->clk_scaling.is_busy_started = true;
 	}
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&hba->clk_scaling.lock, flags);
 }
 
 static void ufshcd_clk_scaling_update_busy(struct ufs_hba *hba)
@@ -2195,7 +2197,7 @@ static void ufshcd_clk_scaling_update_busy(struct ufs_hba *hba)
 	if (!ufshcd_is_clkscaling_supported(hba))
 		return;
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
+	spin_lock_irqsave(&hba->clk_scaling.lock, flags);
 	hba->clk_scaling.active_reqs--;
 	if (!scaling->active_reqs && scaling->is_busy_started) {
 		scaling->tot_busy_t += ktime_to_us(ktime_sub(ktime_get(),
@@ -2203,7 +2205,7 @@ static void ufshcd_clk_scaling_update_busy(struct ufs_hba *hba)
 		scaling->busy_start_t = 0;
 		scaling->is_busy_started = false;
 	}
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	spin_unlock_irqrestore(&hba->clk_scaling.lock, flags);
 }
 
 static inline int ufshcd_monitor_opcode2dir(u8 opcode)
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index 52c822fe2944..058d27bc1e86 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -453,6 +453,7 @@ struct ufs_clk_gating {
  * @is_initialized: Indicates whether clock scaling is initialized or not
  * @is_busy_started: tracks if busy period has started or not
  * @is_suspended: tracks if devfreq is suspended or not
+ * @lock: seriliaze access to the clock_scaling members
  */
 struct ufs_clk_scaling {
 	int active_reqs;
@@ -472,6 +473,7 @@ struct ufs_clk_scaling {
 	bool is_busy_started;
 	bool is_suspended;
 	bool suspend_on_no_request;
+	spinlock_t lock;
 };
 
 #define UFS_EVENT_HIST_LENGTH 8
-- 
2.25.1

Re: [PATCH 2/2] scsi: ufs: core: Introduce a new clock_scaling lock

[Bart Van Assche]

On 10/27/24 1:25 AM, Avri Altman wrote:
> Introduce a new clock gating lock to seriliaze access to the clock
> scaling members instead of the host_lock.

Same feedback as for the previous patch: please fix the spelling of 
"seriliaze", please use guard() and scoped_guard() where appropriate and
please reorder the members of struct ufs_clk_scaling.

Thanks,

Bart.

RE: [PATCH 2/2] scsi: ufs: core: Introduce a new clock_scaling lock

[Avri Altman]

> On 10/27/24 1:25 AM, Avri Altman wrote:
> > Introduce a new clock gating lock to seriliaze access to the clock
> > scaling members instead of the host_lock.
> 
> Same feedback as for the previous patch: please fix the spelling of "seriliaze",
> please use guard() and scoped_guard() where appropriate and please
> reorder the members of struct ufs_clk_scaling.
Done.

Thanks,
Avri

> 
> Thanks,
> 
> Bart.