Author: davidxu
Date: Wed Feb 1 02:53:06 2012
New Revision: 230857
URL: http://svn.freebsd.org/changeset/base/230857
Log:
If multiple threads call kevent() to get AIO events on same kqueue fd,
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
Modified:
head/sys/kern/vfs_aio.c
head/sys/sys/signal.h
Modified: head/sys/kern/vfs_aio.c
==============================================================================
--- head/sys/kern/vfs_aio.c Wed Feb 1 02:16:15 2012 (r230856)
+++ head/sys/kern/vfs_aio.c Wed Feb 1 02:53:06 2012 (r230857)
@@ -1524,6 +1524,7 @@ aio_aqueue(struct thread *td, struct aio
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 aio
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);
Modified: head/sys/sys/signal.h
==============================================================================
--- head/sys/sys/signal.h Wed Feb 1 02:16:15 2012 (r230856)
+++ head/sys/sys/signal.h Wed Feb 1 02:53:06 2012 (r230857)
@@ -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
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