Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | [PATCH] epoll: Fix user space breakage related to EPOLLWAKEUP (was: Re: [-next regression] TCP window full with EPOLLWAKEUP) | Date | Mon, 21 May 2012 21:28:37 +0200 |
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From: Rafael J. Wysocki <rjw@sisk.pl>
Commit 4d7e30d (epoll: Add a flag, EPOLLWAKEUP, to prevent suspend while epoll events are ready) caused some applications to malfunction, because they set the bit corresponding to the new EPOLLWAKEUP flag in their eventpoll flags and they don't have the new CAP_EPOLLWAKEUP capability.
To prevent that from happening, change epoll_ctl() to clear EPOLLWAKEUP in epds.events if the caller doesn't have the CAP_EPOLLWAKEUP capability instead of failing and returning an error code, which allows the affected applications to function normally.
Reported-and-tested-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> --- fs/eventpoll.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux/fs/eventpoll.c =================================================================== --- linux.orig/fs/eventpoll.c +++ linux/fs/eventpoll.c @@ -1711,7 +1711,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, in /* Check if EPOLLWAKEUP is allowed */ if ((epds.events & EPOLLWAKEUP) && !capable(CAP_EPOLLWAKEUP)) - goto error_tgt_fput; + epds.events &= ~EPOLLWAKEUP; /* * We have to check that the file structure underneath the file descriptor
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