2021. január 25., hétfő 12:40 keltezéssel, Hans de Goede írta: > Hi, > > On 1/25/21 12:35 PM, Andy Shevchenko wrote: > > On Mon, Jan 25, 2021 at 1:26 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > >> On 1/25/21 11:57 AM, Andy Shevchenko wrote: > >>> On Mon, Jan 25, 2021 at 9:37 AM Ike Panhc <ike.pan@xxxxxxxxxxxxx> wrote: > >>>> > >>>> On 1/17/21 3:49 AM, Andy Shevchenko wrote: > >>>>> On Wed, Jan 13, 2021 at 8:23 PM Barnabás Pőcze <pobrn@xxxxxxxxxxxxxx> wrote: > >>>>>> > >>>>>> Consumers can differentiate an error from a successful read much more > >>>>>> easily if the read() call fails with the appropriate errno instead of > >>>>>> returning a magic string like "-1". > >>>>> > >>>>> Is user space ready for this (for the record, it seems an ABI breakage)? > >>>>> > >>>> > >>>> read() and getting errno looks sysfs/driver broken to me. I think > >>>> if button/method is not available, it's better to be something like > >>>> sysfs_emit(buf, "%d\n", -ENODEV) > >>> > >>> Either way it will be an ABI breakage. > >> > >> True any change here will be an ABI breakage, but I really do not expect > >> anything to be dependent on this weird behavior of returning errors by > >> writing some magic value to the buffer, rather then just error-ing out > >> of the read() call. > >> > >> The kernel-convention here clearly is to make the read() syscall fail with > >> -ESOMETHING on errors. So I see this as making the driver conform to the > >> expected sysfs API behavior. Since this change is nicely split out into a > >> separate patch, we can always revert it if it turns out there actually > >> is something depending on this. But again I see that as highly > >> unlikely. > > > > Me too. My point is that every stakeholder here understands that. > > Perhaps elaborated in the commit message. > > Ack, adding a note about this to the commit message would be good. > > Barnabás, can you add a note about this to the commit message? > > Also I think we are about ready for you to post a v3 of this > series (when you have time to do so). > Yes, I can add a note about this. I've been relatively busy for some time, but I'm planning to submit the new version shortly (by the end of this week).
