From: Eric Wong <e@80x24.org>
To: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>,
Arnd Bergmann <arnd@arndb.de>, Al Viro <viro@zeniv.linux.org.uk>,
Jason Baron <jbaron@akamai.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Omar Kilani <omar.kilani@gmail.com>,
Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>
Subject: Re: Strange issues with epoll since 5.0
Date: Wed, 1 May 2019 20:48:26 +0000 [thread overview]
Message-ID: <20190501204826.umekxc7oynslakes@dcvr> (raw)
In-Reply-To: <CABeXuvq7gCV2qPOo+Q8jvNyRaTvhkRLRbnL_oJ-AuK7Sp=P3QQ@mail.gmail.com>
Deepa Dinamani <deepa.kernel@gmail.com> wrote:
> So here is my analysis:
<snip everything I agree with>
> So the 854a6ed56839a40f6 seems to be better than the original code in
> that it detects the signal.
OTOH, does matter to anybody that a signal is detected slightly
sooner than it would've been, otherwise?
> But, the problem is that it doesn't
> communicate it to the userspace.
Yup, that's a big problem :)
> So a patch like below solves the problem. This is incomplete. I'll
> verify and send you a proper fix you can test soon. This is just for
> the sake of discussion:
>
> diff --git a/fs/eventpoll.c b/fs/eventpoll.c
> index 4a0e98d87fcc..63a387329c3d 100644
> --- a/fs/eventpoll.c
> +++ b/fs/eventpoll.c
> @@ -2317,7 +2317,7 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct
> epoll_event __user *, events,
> int, maxevents, int, timeout, const sigset_t __user *, sigmask,
> size_t, sigsetsize)
> {
> - int error;
> + int error, signal_detected;
> sigset_t ksigmask, sigsaved;
>
> /*
> @@ -2330,7 +2330,10 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct
> epoll_event __user *, events,
>
> error = do_epoll_wait(epfd, events, maxevents, timeout);
>
> - restore_user_sigmask(sigmask, &sigsaved);
> + signal_detected = restore_user_sigmask(sigmask, &sigsaved);
> +
> + if (signal_detected && !error)
> + return -EITNR;
>
> return error;
Looks like a reasonable API.
> @@ -2862,7 +2862,7 @@ void restore_user_sigmask(const void __user
> *usigmask, sigset_t *sigsaved)
> if (signal_pending(current)) {
> current->saved_sigmask = *sigsaved;
> set_restore_sigmask();
> - return;
> + return 0;
Shouldn't that "return 1" if a signal is pending?
next prev parent reply other threads:[~2019-05-01 20:48 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CA+8F9hicnF=kvjXPZFQy=Pa2HJUS3JS+G9VswFHNQQynPMHGVQ@mail.gmail.com>
[not found] ` <20190424193903.swlfmfuo6cqnpkwa@dcvr>
2019-04-27 9:33 ` Strange issues with epoll since 5.0 Eric Wong
2019-04-27 23:31 ` Deepa Dinamani
2019-04-28 0:48 ` Eric Wong
2019-04-29 20:47 ` Davidlohr Bueso
2019-04-29 21:04 ` Eric Wong
2019-04-30 21:07 ` Deepa Dinamani
2019-05-01 2:14 ` Eric Wong
2019-05-01 2:26 ` Eric Wong
2019-05-01 7:39 ` Eric Wong
2019-05-01 18:37 ` Deepa Dinamani
2019-05-01 20:48 ` Eric Wong [this message]
2019-05-01 20:53 ` Deepa Dinamani
2019-05-03 0:01 ` Deepa Dinamani
2019-05-03 2:34 ` Eric Wong
2019-05-03 3:34 ` Davidlohr Bueso
2019-05-03 3:42 ` [PATCH] signal: Adjust error codes according to restore_user_sigmask() Deepa Dinamani
2019-05-03 6:34 ` Eric Wong
2019-05-03 18:21 ` Deepa Dinamani
2019-05-03 19:51 ` Davidlohr Bueso
2019-05-03 22:53 ` Deepa Dinamani
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