diff mbox series

[10/13] PM / QoS: Teach lockdep about dev_pm_qos_mtx locking order

Message ID 20230312204150.1353517-11-robdclark@gmail.com
State Superseded
Headers show
Series drm/msm+PM+icc: Make job_run() reclaim-safe | expand

Commit Message

Rob Clark March 12, 2023, 8:41 p.m. UTC 
From: Rob Clark <robdclark@chromium.org>

Annotate dev_pm_qos_mtx to teach lockdep to scream about allocations
that could trigger reclaim under dev_pm_qos_mtx.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/base/power/qos.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

Comments

Rafael J. Wysocki March 13, 2023, 12:31 p.m. UTC | #1 
On Sun, Mar 12, 2023 at 9:42 PM Rob Clark <robdclark@gmail.com> wrote:
>
> From: Rob Clark <robdclark@chromium.org>
>
> Annotate dev_pm_qos_mtx to teach lockdep to scream about allocations
> that could trigger reclaim under dev_pm_qos_mtx.

So why is this needed?

> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>  drivers/base/power/qos.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
> index 9cba334b3729..d4addda3944a 100644
> --- a/drivers/base/power/qos.c
> +++ b/drivers/base/power/qos.c
> @@ -1012,3 +1012,14 @@ void dev_pm_qos_hide_latency_tolerance(struct device *dev)
>         pm_runtime_put(dev);
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_tolerance);
> +
> +static int __init dev_pm_qos_init(void)
> +{
> +       /* Teach lockdep about lock ordering wrt. shrinker: */
> +       fs_reclaim_acquire(GFP_KERNEL);
> +       might_lock(&dev_pm_qos_mtx);
> +       fs_reclaim_release(GFP_KERNEL);
> +
> +       return 0;
> +}
> +early_initcall(dev_pm_qos_init);
> --
> 2.39.2
>
Rob Clark March 13, 2023, 2:46 p.m. UTC | #2 
On Mon, Mar 13, 2023 at 5:31 AM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Sun, Mar 12, 2023 at 9:42 PM Rob Clark <robdclark@gmail.com> wrote:
> >
> > From: Rob Clark <robdclark@chromium.org>
> >
> > Annotate dev_pm_qos_mtx to teach lockdep to scream about allocations
> > that could trigger reclaim under dev_pm_qos_mtx.
>
> So why is this needed?

Because it allows lockdep to warn about problems even if it hasn't
seen recursion into shrinker yet.

BR,
-R

> > Signed-off-by: Rob Clark <robdclark@chromium.org>
> > ---
> >  drivers/base/power/qos.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> >
> > diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
> > index 9cba334b3729..d4addda3944a 100644
> > --- a/drivers/base/power/qos.c
> > +++ b/drivers/base/power/qos.c
> > @@ -1012,3 +1012,14 @@ void dev_pm_qos_hide_latency_tolerance(struct device *dev)
> >         pm_runtime_put(dev);
> >  }
> >  EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_tolerance);
> > +
> > +static int __init dev_pm_qos_init(void)
> > +{
> > +       /* Teach lockdep about lock ordering wrt. shrinker: */
> > +       fs_reclaim_acquire(GFP_KERNEL);
> > +       might_lock(&dev_pm_qos_mtx);
> > +       fs_reclaim_release(GFP_KERNEL);
> > +
> > +       return 0;
> > +}
> > +early_initcall(dev_pm_qos_init);
> > --
> > 2.39.2
> >
diff mbox series

Patch

diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
index 9cba334b3729..d4addda3944a 100644
--- a/drivers/base/power/qos.c
+++ b/drivers/base/power/qos.c
@@ -1012,3 +1012,14 @@  void dev_pm_qos_hide_latency_tolerance(struct device *dev)
 	pm_runtime_put(dev);
 }
 EXPORT_SYMBOL_GPL(dev_pm_qos_hide_latency_tolerance);
+
+static int __init dev_pm_qos_init(void)
+{
+	/* Teach lockdep about lock ordering wrt. shrinker: */
+	fs_reclaim_acquire(GFP_KERNEL);
+	might_lock(&dev_pm_qos_mtx);
+	fs_reclaim_release(GFP_KERNEL);
+
+	return 0;
+}
+early_initcall(dev_pm_qos_init);