From: Rafael J. Wysocki <[email protected]>
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 <[email protected]>
Diagnosed-by: Ulf Hansson <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
---
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)
+{
+ 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);
On Thu, 18 Mar 2021 at 19:15, Rafael J. Wysocki <[email protected]> wrote:
>
> From: Rafael J. Wysocki <[email protected]>
>
> 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 <[email protected]>
> Diagnosed-by: Ulf Hansson <[email protected]>
> Signed-off-by: Rafael J. Wysocki <[email protected]>
Just a minor nitpick, see below. In any case:
Reviewed-by: Ulf Hansson <[email protected]>
> ---
> 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
On Fri, Mar 19, 2021 at 2:30 PM Ulf Hansson <[email protected]> wrote:
>
> On Thu, 18 Mar 2021 at 19:15, Rafael J. Wysocki <[email protected]> wrote:
> >
> > From: Rafael J. Wysocki <[email protected]>
> >
> > 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 <[email protected]>
> > Diagnosed-by: Ulf Hansson <[email protected]>
> > Signed-off-by: Rafael J. Wysocki <[email protected]>
>
> Just a minor nitpick, see below. In any case:
>
> Reviewed-by: Ulf Hansson <[email protected]>
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);
> > +}
> > +