Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Thu, 25 Feb 2021 13:06:38 +0100 | Subject | Re: [PATCH v1] PM: runtime: Update device status before letting suppliers suspend |
| |
On Thu, Feb 25, 2021 at 2:32 AM elaine.zhang <zhangqing@rock-chips.com> wrote: > > Hi, Rafael: > > 在 2021/2/25 上午1:53, Rafael J. Wysocki 写道: > > 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 rpm_put_suppliers() called by it may fail. > > > > Fix this by making __rpm_callback() update the device's status to > > RPM_SUSPENDED before calling rpm_put_suppliers() if the current > > status of the device is RPM_SUSPENDING and the callback just invoked > > by it has returned 0 (success). > > > > While at it, modify the code in __rpm_callback() to always check > > the device's PM-runtime status under its PM lock. > > > > 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> > > --- > > > > This is different from the previously posted tentative patch, please retest. > > > > --- > > drivers/base/power/runtime.c | 61 +++++++++++++++++++++++++------------------ > > 1 file changed, 36 insertions(+), 25 deletions(-) > > > > Index: linux-pm/drivers/base/power/runtime.c > > =================================================================== > > --- linux-pm.orig/drivers/base/power/runtime.c > > +++ linux-pm/drivers/base/power/runtime.c > > @@ -325,22 +325,21 @@ static void rpm_put_suppliers(struct dev > > static int __rpm_callback(int (*cb)(struct device *), struct device *dev) > > __releases(&dev->power.lock) __acquires(&dev->power.lock) > > { > > - int retval, idx; > > bool use_links = dev->power.links_count > 0; > > + int retval, idx; > > + bool get, put; > > > > if (dev->power.irq_safe) { > > spin_unlock(&dev->power.lock); > > + } else if (!use_links) { > > + spin_unlock_irq(&dev->power.lock); > > } else { > > + get = dev->power.runtime_status == RPM_RESUMING; > > + > > spin_unlock_irq(&dev->power.lock); > > > > - /* > > - * Resume suppliers if necessary. > > - * > > - * The device's runtime PM status cannot change until this > > - * routine returns, so it is safe to read the status outside of > > - * the lock. > > - */ > > - if (use_links && dev->power.runtime_status == RPM_RESUMING) { > > + /* Resume suppliers if necessary. */ > > + if (get) { > > idx = device_links_read_lock(); > > > > retval = rpm_get_suppliers(dev); > > @@ -355,24 +354,36 @@ static int __rpm_callback(int (*cb)(stru > > > > if (dev->power.irq_safe) { > > spin_lock(&dev->power.lock); > > - } else { > > - /* > > - * If the device is suspending and the callback has returned > > - * success, drop the usage counters of the suppliers that have > > - * been reference counted on its resume. > > - * > > - * Do that if resume fails too. > > - */ > > - if (use_links > > - && ((dev->power.runtime_status == RPM_SUSPENDING && !retval) > > - || (dev->power.runtime_status == RPM_RESUMING && retval))) { > > - idx = device_links_read_lock(); > > + return retval; > > + } > > > > - fail: > > - rpm_put_suppliers(dev); > > + spin_lock_irq(&dev->power.lock); > > > > - device_links_read_unlock(idx); > > - } > > + if (!use_links) > > + return retval; > > + > > + /* > > + * If the device is suspending and the callback has returned success, > > + * drop the usage counters of the suppliers that have been reference > > + * counted on its resume. > > + * > > + * Do that if the resume fails too. > > + */ > > + put = dev->power.runtime_status == RPM_SUSPENDING && !retval; > > + if (put) > > + __update_runtime_status(dev, RPM_SUSPENDED); > > + else > > + put = get && retval; > > + > > + if (put) { > > + spin_unlock_irq(&dev->power.lock); > > + > > + idx = device_links_read_lock(); > > + > > +fail: > > + rpm_put_suppliers(dev); > > + > > + device_links_read_unlock(idx); > > > > spin_lock_irq(&dev->power.lock); > > } > drivers/base/power/runtime.c: In function '__rpm_callback': > drivers/base/power/runtime.c:355:13: warning: 'get' may be used > uninitialized in this function [-Wmaybe-uninitialized] > error, forbidden warning:runtime.c:355
This really is a false-positive, because in fact the "get" variable cannot be uninitialized at this point.
> put = get && retval; > > There is a compilation error. I change it as: > > put = dev->power.runtime_status == RPM_SUSPENDING && retval;
I prefer to initialize "get" to false (even though that is not strictly necessary).
> And test works well.Please check it.
OK, thanks for testing!
I will send an updated patch later today.
| |