On Monday, November 11, 2013 11:26:31 PM Amit Pundir wrote: > I stumbled upon ENOMEM error from epoll_ctl() while bringing up Android-4.4 > on a device that does not yet support PM_SLEEP. Well, Android depends on PM_SLEEP which is a known fact. > While looking into the problem, I found that ep_create_wakeup_source() > reports ENOMEM if wakeup_source_register() returns NULL. > ep_create_wakeup_source() assumes that NULL is only returned if we run > into ENOMEM but NULL is also returned when CONFIG_PM_SLEEP is disabled. So the error value should not be ENOMEM. > If CONFIG_PM_SLEEP is disabled, stripping the EPOLLWAKEUP flag seems to > be a reasonable solution here, allowing the call to succeed, while > dropping the wakeup logic. While returning EINVAL might also be a good > solution, stripping the flag seems to follow the established behavior, > as is done when the process doesn't have sufficient capabilities to > block suspend. Which is a different thing. > I'd appreciate any thoughts or feedback! > > Signed-off-by: Amit Pundir <amit.pundir@xxxxxxxxxx> > --- > fs/eventpoll.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/eventpoll.c b/fs/eventpoll.c > index 473e09d..7a83079 100644 > --- a/fs/eventpoll.c > +++ b/fs/eventpoll.c > @@ -1820,7 +1820,8 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, > goto error_tgt_fput; > > /* Check if EPOLLWAKEUP is allowed */ > - if ((epds.events & EPOLLWAKEUP) && !capable(CAP_BLOCK_SUSPEND)) > + if ((epds.events & EPOLLWAKEUP) && > + (!capable(CAP_BLOCK_SUSPEND) || !IS_ENABLED(CONFIG_PM_SLEEP))) I don't particularly like mixing the checking of CONFIG_ symbols with code like this. I'd create a static inline function taking a pointer to epds.events that would do the if ((epds.events & EPOLLWAKEUP) && !capable(CAP_BLOCK_SUSPEND)) epds.events &= ~EPOLLWAKEUP; for CONFIG_PM_SLEEP set and epds.events &= ~EPOLLWAKEUP; unconditionally for CONFIG_PM_SLEEP unset. Thanks! -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
