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Linux epoll: Don't deregister file descriptor after EPOLLONESHOT is fired

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Linux epoll does not remove descriptor after one-shot event has been triggered.
Set EV_DISPATCH kqueue flag rather then EV_ONESHOT to get the same behavior.

Required by Linux Steam client.

PR:		240590
Reported by:	Alex S <iwtcex@gmail.com>
Reviewed by:	emaste, imp
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D22513
This commit is contained in:
wulf 2019-11-24 20:41:47 +00:00
parent b8d6a9ae5f
commit f94c7eb751
1 changed files with 5 additions and 4 deletions
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9
sys/compat/linux/linux_event.c
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@ -306,7 +306,7 @@ epoll_to_kevent(struct thread *td, struct file *epfp,
/* flags related to how event is registered */
if ((levents & LINUX_EPOLLONESHOT) != 0)
*kev_flags |= EV_ONESHOT;
*kev_flags |= EV_DISPATCH;
if ((levents & LINUX_EPOLLET) != 0)
*kev_flags |= EV_CLEAR;
if ((levents & LINUX_EPOLLERR) != 0)
@ -501,16 +501,17 @@ linux_epoll_ctl(struct thread *td, struct linux_epoll_ctl_args *args)
case LINUX_EPOLL_CTL_ADD:
/*
* kqueue_register() return ENOENT if event does not exists
* and the EV_ADD flag is not set.
* and the EV_ADD flag is not set. Reset EV_ENABLE flag to
* avoid accidental activation of fired oneshot events.
*/
kev[0].flags &= ~EV_ADD;
kev[0].flags &= ~(EV_ADD | EV_ENABLE);
error = kqfd_register(args->epfd, &kev[0], td, M_WAITOK);
if (error != ENOENT) {
error = EEXIST;
goto leave0;
}
error = 0;
kev[0].flags |= EV_ADD;
kev[0].flags |= (EV_ADD | EV_ENABLE);
break;
case LINUX_EPOLL_CTL_DEL: