On Mon, Nov 9, 2020 at 5:15 PM zhangqilong <zhangqilo...@huawei.com> wrote: > > Hi > > > > > 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/20200520 > > > > > 0951 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? > > 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!
