On Sun, Aug 4, 2019 at 12:40 AM Tri Vo <tr...@android.com> wrote: > > On Thu, Aug 1, 2019 at 3:10 PM Rafael J. Wysocki <raf...@kernel.org> wrote: > > > > On Thu, Aug 1, 2019 at 11:45 PM Tri Vo <tr...@android.com> wrote: > > > > > > On Thu, Aug 1, 2019 at 1:23 PM Stephen Boyd <swb...@chromium.org> wrote: > > > > > > > > Quoting Tri Vo (2019-08-01 12:50:25) > > > > > On Wed, Jul 31, 2019 at 4:45 PM Stephen Boyd <swb...@chromium.org> > > > > > wrote: > > > > > > > > > > > > Quoting Rafael J. Wysocki (2019-07-31 16:10:38) > > > > > > > On Thu, Aug 1, 2019 at 12:59 AM Tri Vo <tr...@android.com> wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > So why wouldn't something like this suffice: > > > > > > > > > > > > > > > > > > dev = device_create_with_groups(wakeup_class, parent, > > > > > > > > > MKDEV(0, 0), ws, > > > > > > > > > wakeup_source_groups, > > > > > > > > > "wakeup:%s", ws->name); > > > > > > > > > > > > > > > > > > ? > > > > > > > > > > > > > > > > ws->name is inherited from the device name. IIUC device names > > > > > > > > are not > > > > > > > > guaranteed to be unique. So if different devices with the same > > > > > > > > name > > > > > > > > register wakeup sources, there is an error. > > > > > > > > > > > > > > OK > > > > > > > > > > > > > > So I guess the names are retained for backwards compatibility with > > > > > > > existing user space that may be using them? > > > > > > > > > > > > > > That's kind of fair enough, but having two different > > > > > > > identification > > > > > > > schemes for wakeup sources will end up confusing. > > > > > > > > > > > > I understand your concern about the IDA now. Thanks for clarifying. > > > > > > > > > > > > How about we name the devices 'wakeupN' with the IDA when they're > > > > > > registered with a non-NULL device pointer and then name them > > > > > > whatever > > > > > > the name argument is when the device pointer is NULL. If we have > > > > > > this, > > > > > > we should be able to drop the name attribute in sysfs and figure > > > > > > out the > > > > > > name either by looking at the device name in /sys/class/wakeup/ if > > > > > > it > > > > > > isn't 'wakeupN', or follow the symlink to the device in > > > > > > /sys/devices/ > > > > > > and look at the parent device name there. > > > > > > > > > > This makes it difficult for userspace to query the name a wakeup > > > > > source, as it now has to first figure out if a wakeup source is > > > > > associated with a device or not. The criteria for that is also > > > > > awkward, userspase has to check if directory path contains "wakeupN", > > > > > then it's a virtual wakeup source. > > > > > > > > I think you mean if it doesn't match wakeupN then it's a virtual wakeup > > > > source? > > > > > > Yes > > > > > > > > > > > > > > IMO it's cleaner to consistently have /sys/class/wakeup/wakeupN/name > > > > > for every wakeup source. > > > > > > > > I don't find it awkward or difficult. Just know what the name of the > > > > /sys/class/wakeup/ path is and then extract the name from there if it > > > > doesn't match wakeupN, otherwise read the 'device' symlink and run it > > > > through basename. > > > > > > The concern was that having both "id" and "name" around might be > > > confusing. I don't think that making the presence of "name" > > > conditional helps here. And we have to maintain additional logic in > > > both kernel and userspace to support this. > > > > > > Also, say, userspace grabs a wakelock named "wakeup0". In the current > > > patch, this results in a name collision and an error. Even assuming > > > that userspace doesn't have ill intent, it still needs to be aware of > > > "wakeupN" naming pattern to avoid this error condition. > > > > > > All wakeup sources in the /sys/class/wakeup/ are in the same namespace > > > regardless of where they originate from, i.e. we have to either (1) > > > inspect the name of a wakeup source and make sure it's unique before > > > using it as a directory name OR (2) generate the directory name on > > > behalf of whomever is registering a wakeup source, which I think is a > > > much simpler solution. > > > > OK, whatever. > > > > Let's use the IDA as originally proposed and retain the names for > > backwards compatibility only. > > > > Maybe just allocate the ID at the wakeup source object creation time > > already (ISTR that you did that before attempting to create a virtual > > device for the wakeup source). > > Yes, allocating the ID when creating the wakeup source object makes > sense. However, kernel/power/wakelock.c allocates its wakeup sources > manually. I imagine we don't want these IDs to be created in more than > one place.
No, we don't. > Making wakelock.c only use wakeup_source_*() family of functions when > dealing with wakeup sources might be a worthwhile change though. Then > we won't have to worry about ID allocation in wakelock.c. WDYT? Sounds reasonable to me. > Also, it sounds like we all agree with "/sys/class/wakeup/wsN/" path > and "/sys/class/wakeup/wsN/name" attribute for each wakeup source, > right? Generally yes, but please make it "wakeupN".
