| Message ID | 20201109150416.1877878-2-zhangqilong3@huawei.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,1/2] PM: runtime: Add a general runtime get sync operation to deal with usage counter | expand |
On Mon, 9 Nov 2020 at 16:20, Rafael J. Wysocki <rafael@kernel.org> wrote: > > On Mon, Nov 9, 2020 at 4:00 PM Zhang Qilong <zhangqilong3@huawei.com> wrote: > > > > In many case, we need to check return value of pm_runtime_get_sync, but > > it brings a trouble to the usage counter processing. Many callers forget > > to decrease the usage counter when it failed. It has been discussed a > > lot[0][1]. So we add a function to deal with the usage counter for better > > coding. > > > > [0]https://lkml.org/lkml/2020/6/14/88 > > [1]https://patchwork.ozlabs.org/project/linux-tegra/patch/20200520095148.10995-1-dinghao.liu@zju.edu.cn/ > > Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com> > > --- > > include/linux/pm_runtime.h | 30 ++++++++++++++++++++++++++++++ > > 1 file changed, 30 insertions(+) > > > > diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h > > index 4b708f4e8eed..6549ce764400 100644 > > --- a/include/linux/pm_runtime.h > > +++ b/include/linux/pm_runtime.h > > @@ -386,6 +386,36 @@ static inline int pm_runtime_get_sync(struct device *dev) > > return __pm_runtime_resume(dev, RPM_GET_PUT); > > } > > > > +/** > > + * pm_runtime_general_get - Bump up usage counter of a device and resume it. > > + * @dev: Target device. > > + * > > + * Increase runtime PM usage counter of @dev first, and carry out runtime-resume > > + * of it synchronously. If __pm_runtime_resume return negative value(device is in > > + * error state), we to need decrease the usage counter before it return. If > > + * __pm_runtime_resume return positive value, it means the runtime of device has > > + * already been in active state, and we let the new wrapper return zero instead. > > + * > > + * The possible return values of this function is zero or negative value. > > + * zero: > > + * - it means resume succeeed or runtime of device has already been active, the > > + * runtime PM usage counter of @dev remains incremented. > > + * negative: > > + * - it means failure and the runtime PM usage counter of @dev has been balanced. > > The kerneldoc above is kind of noisy and it is hard to figure out what > the helper really does from it. > > You could basically say something like "Resume @dev synchronously and > if that is successful, increment its runtime PM usage counter. Return > 0 if the runtime PM usage counter of @dev has been incremented or a > negative error code otherwise." > > > + */ > > +static inline int pm_runtime_general_get(struct device *dev) > > What about pm_runtime_resume_and_get()? We already have pm_runtime_get_if_active() - so perhaps pm_runtime_get_if_suspended() could be an option as well? > > > +{ > > + int ret = 0; > > This extra initialization is not necessary. > > You can initialize ret to the __pm_runtime_resume() return value right away. > > > + > > + ret = __pm_runtime_resume(dev, RPM_GET_PUT); > > + if (ret < 0) { > > + pm_runtime_put_noidle(dev); > > + return ret; > > + } > > + > > + return 0; > > +} > > + > > /** > > * pm_runtime_put - Drop device usage counter and queue up "idle check" if 0. > > * @dev: Target device. > > -- Kind regards Uffe
On Mon, Nov 9, 2020 at 4:50 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > > On Mon, 9 Nov 2020 at 16:20, Rafael J. Wysocki <rafael@kernel.org> wrote: > > > > On Mon, Nov 9, 2020 at 4:00 PM Zhang Qilong <zhangqilong3@huawei.com> wrote: > > > > > > In many case, we need to check return value of pm_runtime_get_sync, but > > > it brings a trouble to the usage counter processing. Many callers forget > > > to decrease the usage counter when it failed. It has been discussed a > > > lot[0][1]. So we add a function to deal with the usage counter for better > > > coding. > > > > > > [0]https://lkml.org/lkml/2020/6/14/88 > > > [1]https://patchwork.ozlabs.org/project/linux-tegra/patch/20200520095148.10995-1-dinghao.liu@zju.edu.cn/ > > > Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com> > > > --- > > > include/linux/pm_runtime.h | 30 ++++++++++++++++++++++++++++++ > > > 1 file changed, 30 insertions(+) > > > > > > diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h > > > index 4b708f4e8eed..6549ce764400 100644 > > > --- a/include/linux/pm_runtime.h > > > +++ b/include/linux/pm_runtime.h > > > @@ -386,6 +386,36 @@ static inline int pm_runtime_get_sync(struct device *dev) > > > return __pm_runtime_resume(dev, RPM_GET_PUT); > > > } > > > > > > +/** > > > + * pm_runtime_general_get - Bump up usage counter of a device and resume it. > > > + * @dev: Target device. > > > + * > > > + * Increase runtime PM usage counter of @dev first, and carry out runtime-resume > > > + * of it synchronously. If __pm_runtime_resume return negative value(device is in > > > + * error state), we to need decrease the usage counter before it return. If > > > + * __pm_runtime_resume return positive value, it means the runtime of device has > > > + * already been in active state, and we let the new wrapper return zero instead. > > > + * > > > + * The possible return values of this function is zero or negative value. > > > + * zero: > > > + * - it means resume succeeed or runtime of device has already been active, the > > > + * runtime PM usage counter of @dev remains incremented. > > > + * negative: > > > + * - it means failure and the runtime PM usage counter of @dev has been balanced. > > > > The kerneldoc above is kind of noisy and it is hard to figure out what > > the helper really does from it. > > > > You could basically say something like "Resume @dev synchronously and > > if that is successful, increment its runtime PM usage counter. Return > > 0 if the runtime PM usage counter of @dev has been incremented or a > > negative error code otherwise." > > > > > + */ > > > +static inline int pm_runtime_general_get(struct device *dev) > > > > What about pm_runtime_resume_and_get()? > > We already have pm_runtime_get_if_active() - so perhaps > pm_runtime_get_if_suspended() could be an option as well? It doesn't work this way, though. The "get" happens even if the device has not been suspended.
On Mon, Nov 9, 2020 at 5:15 PM zhangqilong <zhangqilong3@huawei.com> wrote: > > Hi > > > > > On Mon, Nov 9, 2020 at 4:50 PM zhangqilong <zhangqilong3@huawei.com> > > wrote: > > > > > > > operation to deal with usage counter > > > > > > > > On Mon, Nov 9, 2020 at 4:00 PM Zhang Qilong > > > > <zhangqilong3@huawei.com> > > > > wrote: > > > > > > > > > > In many case, we need to check return value of > > > > > pm_runtime_get_sync, but it brings a trouble to the usage counter > > > > > processing. Many callers forget to decrease the usage counter when > > > > > it failed. It has been discussed a lot[0][1]. So we add a function > > > > > to deal with the usage counter for better coding. > > > > > > > > > > [0]https://lkml.org/lkml/2020/6/14/88 > > > > > [1]https://patchwork.ozlabs.org/project/linux-tegra/patch/20200520 > > > > > 0951 48.10995-1-dinghao.liu@zju.edu.cn/ > > > > > Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com> > > > > > --- > > > > > include/linux/pm_runtime.h | 30 ++++++++++++++++++++++++++++++ > > > > > 1 file changed, 30 insertions(+) > > > > > > > > > > diff --git a/include/linux/pm_runtime.h > > > > > b/include/linux/pm_runtime.h index 4b708f4e8eed..6549ce764400 > > > > > 100644 > > > > > --- a/include/linux/pm_runtime.h > > > > > +++ b/include/linux/pm_runtime.h > > > > > @@ -386,6 +386,36 @@ static inline int pm_runtime_get_sync(struct > > > > > device > > > > *dev) > > > > > return __pm_runtime_resume(dev, RPM_GET_PUT); } > > > > > > > > > > +/** > > > > > + * pm_runtime_general_get - Bump up usage counter of a device and > > > > resume it. > > > > > + * @dev: Target device. > > > > > + * > > > > > + * Increase runtime PM usage counter of @dev first, and carry out > > > > > +runtime-resume > > > > > + * of it synchronously. If __pm_runtime_resume return negative > > > > > +value(device is in > > > > > + * error state), we to need decrease the usage counter before it > > > > > +return. If > > > > > + * __pm_runtime_resume return positive value, it means the > > > > > +runtime of device has > > > > > + * already been in active state, and we let the new wrapper > > > > > +return zero > > > > instead. > > > > > + * > > > > > + * The possible return values of this function is zero or negative value. > > > > > + * zero: > > > > > + * - it means resume succeeed or runtime of device has already been > > > > active, the > > > > > + * runtime PM usage counter of @dev remains incremented. > > > > > + * negative: > > > > > + * - it means failure and the runtime PM usage counter of @dev has > > > > been balanced. > > > > > > > > The kerneldoc above is kind of noisy and it is hard to figure out > > > > what the helper really does from it. > > > > > > > > You could basically say something like "Resume @dev synchronously > > > > and if that is successful, increment its runtime PM usage counter. > > > > Return > > > > 0 if the runtime PM usage counter of @dev has been incremented or a > > > > negative error code otherwise." > > > > > > > > > > How about the following description. > > > /** > > > 390 * pm_runtime_general_get - Bump up usage counter of a device and > > resume it. > > > 391 * @dev: Target device. > > > 392 * > > > 393 * Increase runtime PM usage counter of @dev first, and carry out > > > runtime-resume > > > 394 * of it synchronously. If __pm_runtime_resume return negative > > > value(device is in > > > 395 * error state), we to need decrease the usage counter before it > > > return. If > > > 396 * __pm_runtime_resume return positive value, it means the runtime > > > of device has > > > 397 * already been in active state, and we let the new wrapper return zero > > instead. > > > 398 * > > > > If you add the paragraph below, the one above becomes redundant IMV. > > > > > 399 * Resume @dev synchronously and if that is successful, and > > > increment its runtime > > > > "Resume @dev synchronously and if that is successful, increment its runtime" > > > > (drop the extra "and"). > > > > > 400 * PM usage counter if it turn out to equal to 0. The runtime PM > > > usage counter of > > > > The "if it turn out to equal to 0" phrase is redundant (and the grammar in it is > > incorrect). > > > > > 401 * @dev has been incremented or a negative error code otherwise. > > > 402 */ > > > > Why don't you use what I said verbatim? > > I had misunderstand just now, sorry for that. The description is as follows: > 389 /** > 390 * pm_runtime_resume_and_get - Bump up usage counter of a device and resume it. > 391 * @dev: Target device. > 392 * > 393 * Resume @dev synchronously if that is successful, increment its runtime PM "Resume @dev synchronously and if that is successful, increment its runtime PM" (missing "and"). > 394 * usage counter. Return 0 if the runtime PM usage counter of @dev has been > 395 * incremented or a negative error code otherwise. > 396 */ > > Do you think it's OK? Apart from the above typo, yes it is. Thanks!
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h index 4b708f4e8eed..6549ce764400 100644 --- a/include/linux/pm_runtime.h +++ b/include/linux/pm_runtime.h @@ -386,6 +386,36 @@ static inline int pm_runtime_get_sync(struct device *dev) return __pm_runtime_resume(dev, RPM_GET_PUT); } +/** + * pm_runtime_general_get - Bump up usage counter of a device and resume it. + * @dev: Target device. + * + * Increase runtime PM usage counter of @dev first, and carry out runtime-resume + * of it synchronously. If __pm_runtime_resume return negative value(device is in + * error state), we to need decrease the usage counter before it return. If + * __pm_runtime_resume return positive value, it means the runtime of device has + * already been in active state, and we let the new wrapper return zero instead. + * + * The possible return values of this function is zero or negative value. + * zero: + * - it means resume succeeed or runtime of device has already been active, the + * runtime PM usage counter of @dev remains incremented. + * negative: + * - it means failure and the runtime PM usage counter of @dev has been balanced. + */ +static inline int pm_runtime_general_get(struct device *dev) +{ + int ret = 0; + + ret = __pm_runtime_resume(dev, RPM_GET_PUT); + if (ret < 0) { + pm_runtime_put_noidle(dev); + return ret; + } + + return 0; +} + /** * pm_runtime_put - Drop device usage counter and queue up "idle check" if 0. * @dev: Target device.
In many case, we need to check return value of pm_runtime_get_sync, but it brings a trouble to the usage counter processing. Many callers forget to decrease the usage counter when it failed. It has been discussed a lot[0][1]. So we add a function to deal with the usage counter for better coding. [0]https://lkml.org/lkml/2020/6/14/88 [1]https://patchwork.ozlabs.org/project/linux-tegra/patch/20200520095148.10995-1-dinghao.liu@zju.edu.cn/ Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com> --- include/linux/pm_runtime.h | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+)