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If multiple threads call kevent() to get AIO events on same kqueue fd,

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it is possible that a single AIO event will be reported to multiple
threads, it is not threading friendly, and the existing API can not
control this behavior.
Allocate a kevent flags field sigev_notify_kevent_flags for AIO event
notification in sigevent, and allow user to pass EV_CLEAR, EV_DISPATCH
or EV_ONESHOT to AIO kernel code, user can control whether the event
should be cleared once it is retrieved by a thread. This change should
be comptaible with existing application, because the field should have
already been zero-filled, and no additional action will be taken by
kernel.

PR:	kern/156567
This commit is contained in:
davidxu 2012-02-01 02:53:06 +00:00
parent 9b7841536b
commit e9edcfe7c1
2 changed files with 9 additions and 1 deletions
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8
sys/kern/vfs_aio.c
View File

@ -1524,6 +1524,7 @@ aio_aqueue(struct thread *td, struct aiocb *job, struct aioliojob *lj,
int error;
int fd, kqfd;
int jid;
u_short evflags;
if (p->p_aioinfo == NULL)
aio_init_aioinfo(p);
@ -1646,10 +1647,15 @@ aio_aqueue(struct thread *td, struct aiocb *job, struct aioliojob *lj,
if (aiocbe->uaiocb.aio_sigevent.sigev_notify != SIGEV_KEVENT)
goto no_kqueue;
evflags = aiocbe->uaiocb.aio_sigevent.sigev_notify_kevent_flags;
if ((evflags & ~(EV_CLEAR | EV_DISPATCH | EV_ONESHOT)) != 0) {
error = EINVAL;
goto aqueue_fail;
}
kqfd = aiocbe->uaiocb.aio_sigevent.sigev_notify_kqueue;
kev.ident = (uintptr_t)aiocbe->uuaiocb;
kev.filter = EVFILT_AIO;
kev.flags = EV_ADD | EV_ENABLE | EV_FLAG1;
kev.flags = EV_ADD | EV_ENABLE | EV_FLAG1 | evflags;
kev.data = (intptr_t)aiocbe;
kev.udata = aiocbe->uaiocb.aio_sigevent.sigev_value.sival_ptr;
error = kqfd_register(kqfd, &kev, td, 1);

2
sys/sys/signal.h
View File

@ -169,12 +169,14 @@ struct sigevent {
void (*_function)(union sigval);
void *_attribute; /* pthread_attr_t * */
} _sigev_thread;
unsigned short _kevent_flags;
long __spare__[8];
} _sigev_un;
};
#if __BSD_VISIBLE
#define sigev_notify_kqueue sigev_signo
#define sigev_notify_kevent_flags _sigev_un._kevent_flags
#define sigev_notify_thread_id _sigev_un._threadid
#endif
#define sigev_notify_function _sigev_un._sigev_thread._function