| Message ID | 1930477.9OOUKYNkGr@kreacher |
|---|---|
| State | New |
| Headers | show |
| Series | [v1] PM: runtime: Update device status before letting suppliers suspend | expand |
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 put = get && retval; There is a compilation error. I change it as: put = dev->power.runtime_status == RPM_SUSPENDING && retval; And test works well.Please check it. > > > > > >
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.
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); }