[v1,2/2] PM: runtime: Defer suspending suppliers
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Message ID 2060154.irdbgypaU6@kreacher
State New, archived
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Series
  • Untitled series #490278
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Commit Message

Rafael J. Wysocki March 18, 2021, 6:15 p.m. UTC
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Because the PM-runtime status of the device is not updated in
__rpm_callback(), attempts to suspend the suppliers of the given
device triggered by the rpm_put_suppliers() call in there may fail.

To fix this (1) modify __rpm_callback() to avoid attempting to
actually suspend the suppliers, but only decrease their PM-runtime
usage counters and (2) make rpm_suspend() try to suspend the suppliers
after changing the device's PM-runtime status, in analogy with the
handling of the device's parent.

Link: https://lore.kernel.org/linux-pm/CAPDyKFqm06KDw_p8WXsM4dijDbho4bb6T4k50UqqvR1_COsp8g@mail.gmail.com/
Fixes: 21d5c57b3726 ("PM / runtime: Use device links")
Reported-by: elaine.zhang <zhangqing@rock-chips.com>
Diagnosed-by: Ulf Hansson <ulf.hansson@linaro.org> 
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/base/power/runtime.c |   45 +++++++++++++++++++++++++++++++++++++------
 1 file changed, 39 insertions(+), 6 deletions(-)

Comments

Ulf Hansson March 19, 2021, 1:29 p.m. UTC | #1
On Thu, 18 Mar 2021 at 19:15, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Because the PM-runtime status of the device is not updated in
> __rpm_callback(), attempts to suspend the suppliers of the given
> device triggered by the rpm_put_suppliers() call in there may fail.
>
> To fix this (1) modify __rpm_callback() to avoid attempting to
> actually suspend the suppliers, but only decrease their PM-runtime
> usage counters and (2) make rpm_suspend() try to suspend the suppliers
> after changing the device's PM-runtime status, in analogy with the
> handling of the device's parent.
>
> Link: https://lore.kernel.org/linux-pm/CAPDyKFqm06KDw_p8WXsM4dijDbho4bb6T4k50UqqvR1_COsp8g@mail.gmail.com/
> Fixes: 21d5c57b3726 ("PM / runtime: Use device links")
> Reported-by: elaine.zhang <zhangqing@rock-chips.com>
> Diagnosed-by: Ulf Hansson <ulf.hansson@linaro.org>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Just a minor nitpick, see below. In any case:

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

> ---
>  drivers/base/power/runtime.c |   45 +++++++++++++++++++++++++++++++++++++------
>  1 file changed, 39 insertions(+), 6 deletions(-)
>
> Index: linux-pm/drivers/base/power/runtime.c
> ===================================================================
> --- linux-pm.orig/drivers/base/power/runtime.c
> +++ linux-pm/drivers/base/power/runtime.c
> @@ -305,7 +305,7 @@ static int rpm_get_suppliers(struct devi
>         return 0;
>  }
>
> -static void rpm_put_suppliers(struct device *dev)
> +static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend)
>  {
>         struct device_link *link;
>
> @@ -313,10 +313,30 @@ static void rpm_put_suppliers(struct dev
>                                 device_links_read_lock_held()) {
>
>                 while (refcount_dec_not_one(&link->rpm_active))
> -                       pm_runtime_put(link->supplier);
> +                       pm_runtime_put_noidle(link->supplier);
> +
> +               if (try_to_suspend)
> +                       pm_request_idle(link->supplier);
>         }
>  }
>
> +static void rpm_put_suppliers(struct device *dev)
> +{
> +       __rpm_put_suppliers(dev, true);
> +}
> +
> +static void rpm_try_to_suspend_suppliers(struct device *dev)

Maybe "rpm_suspend_suppliers" is sufficient for the name of the
function, but I have no strong opinion.

> +{
> +       struct device_link *link;
> +       int idx = device_links_read_lock();
> +
> +       list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
> +                               device_links_read_lock_held())
> +               pm_request_idle(link->supplier);
> +
> +       device_links_read_unlock(idx);
> +}
> +

[...]

Kind regards
Uffe
Rafael J. Wysocki March 19, 2021, 1:48 p.m. UTC | #2
On Fri, Mar 19, 2021 at 2:30 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
> On Thu, 18 Mar 2021 at 19:15, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> >
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > Because the PM-runtime status of the device is not updated in
> > __rpm_callback(), attempts to suspend the suppliers of the given
> > device triggered by the rpm_put_suppliers() call in there may fail.
> >
> > To fix this (1) modify __rpm_callback() to avoid attempting to
> > actually suspend the suppliers, but only decrease their PM-runtime
> > usage counters and (2) make rpm_suspend() try to suspend the suppliers
> > after changing the device's PM-runtime status, in analogy with the
> > handling of the device's parent.
> >
> > Link: https://lore.kernel.org/linux-pm/CAPDyKFqm06KDw_p8WXsM4dijDbho4bb6T4k50UqqvR1_COsp8g@mail.gmail.com/
> > Fixes: 21d5c57b3726 ("PM / runtime: Use device links")
> > Reported-by: elaine.zhang <zhangqing@rock-chips.com>
> > Diagnosed-by: Ulf Hansson <ulf.hansson@linaro.org>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Just a minor nitpick, see below. In any case:
>
> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

Thanks!

>
> > ---
> >  drivers/base/power/runtime.c |   45 +++++++++++++++++++++++++++++++++++++------
> >  1 file changed, 39 insertions(+), 6 deletions(-)
> >
> > Index: linux-pm/drivers/base/power/runtime.c
> > ===================================================================
> > --- linux-pm.orig/drivers/base/power/runtime.c
> > +++ linux-pm/drivers/base/power/runtime.c
> > @@ -305,7 +305,7 @@ static int rpm_get_suppliers(struct devi
> >         return 0;
> >  }
> >
> > -static void rpm_put_suppliers(struct device *dev)
> > +static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend)
> >  {
> >         struct device_link *link;
> >
> > @@ -313,10 +313,30 @@ static void rpm_put_suppliers(struct dev
> >                                 device_links_read_lock_held()) {
> >
> >                 while (refcount_dec_not_one(&link->rpm_active))
> > -                       pm_runtime_put(link->supplier);
> > +                       pm_runtime_put_noidle(link->supplier);
> > +
> > +               if (try_to_suspend)
> > +                       pm_request_idle(link->supplier);
> >         }
> >  }
> >
> > +static void rpm_put_suppliers(struct device *dev)
> > +{
> > +       __rpm_put_suppliers(dev, true);
> > +}
> > +
> > +static void rpm_try_to_suspend_suppliers(struct device *dev)
>
> Maybe "rpm_suspend_suppliers" is sufficient for the name of the
> function, but I have no strong opinion.

OK

In addition to this, spin_unlock_irq()/spin_lock_irq() need to be used
around the call to it in rpm_suspend(), so I'll send a v2.  I guess
that the R-by still applies, though. :-)

> > +{
> > +       struct device_link *link;
> > +       int idx = device_links_read_lock();
> > +
> > +       list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
> > +                               device_links_read_lock_held())
> > +               pm_request_idle(link->supplier);
> > +
> > +       device_links_read_unlock(idx);
> > +}
> > +

Patch
diff mbox series

Index: linux-pm/drivers/base/power/runtime.c
===================================================================
--- linux-pm.orig/drivers/base/power/runtime.c
+++ linux-pm/drivers/base/power/runtime.c
@@ -305,7 +305,7 @@  static int rpm_get_suppliers(struct devi
 	return 0;
 }
 
-static void rpm_put_suppliers(struct device *dev)
+static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend)
 {
 	struct device_link *link;
 
@@ -313,10 +313,30 @@  static void rpm_put_suppliers(struct dev
 				device_links_read_lock_held()) {
 
 		while (refcount_dec_not_one(&link->rpm_active))
-			pm_runtime_put(link->supplier);
+			pm_runtime_put_noidle(link->supplier);
+
+		if (try_to_suspend)
+			pm_request_idle(link->supplier);
 	}
 }
 
+static void rpm_put_suppliers(struct device *dev)
+{
+	__rpm_put_suppliers(dev, true);
+}
+
+static void rpm_try_to_suspend_suppliers(struct device *dev)
+{
+	struct device_link *link;
+	int idx = device_links_read_lock();
+
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
+				device_links_read_lock_held())
+		pm_request_idle(link->supplier);
+
+	device_links_read_unlock(idx);
+}
+
 /**
  * __rpm_callback - Run a given runtime PM callback for a given device.
  * @cb: Runtime PM callback to run.
@@ -344,8 +364,10 @@  static int __rpm_callback(int (*cb)(stru
 			idx = device_links_read_lock();
 
 			retval = rpm_get_suppliers(dev);
-			if (retval)
+			if (retval) {
+				rpm_put_suppliers(dev);
 				goto fail;
+			}
 
 			device_links_read_unlock(idx);
 		}
@@ -368,9 +390,9 @@  static int __rpm_callback(int (*cb)(stru
 		    || (dev->power.runtime_status == RPM_RESUMING && retval))) {
 			idx = device_links_read_lock();
 
- fail:
-			rpm_put_suppliers(dev);
+			__rpm_put_suppliers(dev, false);
 
+fail:
 			device_links_read_unlock(idx);
 		}
 
@@ -642,8 +664,11 @@  static int rpm_suspend(struct device *de
 		goto out;
 	}
 
+	if (dev->power.irq_safe)
+		goto out;
+
 	/* Maybe the parent is now able to suspend. */
-	if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
+	if (parent && !parent->power.ignore_children) {
 		spin_unlock(&dev->power.lock);
 
 		spin_lock(&parent->power.lock);
@@ -652,6 +677,14 @@  static int rpm_suspend(struct device *de
 
 		spin_lock(&dev->power.lock);
 	}
+	/* Maybe the suppliers are now able to suspend. */
+	if (dev->power.links_count > 0) {
+		spin_unlock(&dev->power.lock);
+
+		rpm_try_to_suspend_suppliers(dev);
+
+		spin_lock(&dev->power.lock);
+	}
 
  out:
 	trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);