On Mon, Nov 9, 2020 at 4:50 PM zhangqilong <zhangqilo...@huawei.com> wrote: > > > operation to deal with usage counter > > > > On Mon, Nov 9, 2020 at 4:00 PM Zhang Qilong <zhangqilo...@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/202005200951 > > > 48.10995-1-dinghao....@zju.edu.cn/ > > > Signed-off-by: Zhang Qilong <zhangqilo...@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?
