diff options
author | Jens Axboe <axboe@kernel.dk> | 2022-11-05 10:17:33 -0600 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2022-12-01 11:01:20 -0700 |
commit | 1265ae6b60afb035f4a1a0594a928902238c42f4 (patch) | |
tree | 3c76fd8bd57efd90f5234374a33c46e79429149f | |
parent | 67c6e1c9a12e2ea23f70e1d13b2dd1476090adea (diff) |
eventpoll: add method for configuring minimum wait on epoll context
Add support for EPOLL_CTL_MIN_WAIT, which can be used to define a
minimum reap time for an epoll context.
Basic test case:
struct d {
int p1, p2;
};
static void *fn(void *data)
{
struct d *d = data;
char b = 0x89;
/* Generate 2 events 20 msec apart */
usleep(10000);
write(d->p1, &b, sizeof(b));
usleep(10000);
write(d->p2, &b, sizeof(b));
return NULL;
}
int main(int argc, char *argv[])
{
struct epoll_event ev, events[2];
pthread_t thread;
int p1[2], p2[2];
struct d d;
int efd, ret;
efd = epoll_create1(0);
if (efd < 0) {
perror("epoll_create");
return 1;
}
if (pipe(p1) < 0) {
perror("pipe");
return 1;
}
if (pipe(p2) < 0) {
perror("pipe");
return 1;
}
ev.events = EPOLLIN;
ev.data.fd = p1[0];
if (epoll_ctl(efd, EPOLL_CTL_ADD, p1[0], &ev) < 0) {
perror("epoll add");
return 1;
}
ev.events = EPOLLIN;
ev.data.fd = p2[0];
if (epoll_ctl(efd, EPOLL_CTL_ADD, p2[0], &ev) < 0) {
perror("epoll add");
return 1;
}
/* always wait 200 msec for events */
ev.data.u64 = 200000;
if (epoll_ctl(efd, EPOLL_CTL_MIN_WAIT, -1, &ev) < 0) {
perror("epoll add set timeout");
return 1;
}
d.p1 = p1[1];
d.p2 = p2[1];
pthread_create(&thread, NULL, fn, &d);
/* expect to get 2 events here rather than just 1 */
ret = epoll_wait(efd, events, 2, -1);
printf("epoll_wait=%d\n", ret);
return 0;
}
If EPOLL_CTL_MIN_WAIT is used with a timeout of 0, it is a no-op, and
acts the same as if it wasn't called to begin with. Only a non-zero
usec delay value will result in a wait time being applied for reaping
events.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r-- | fs/eventpoll.c | 13 | ||||
-rw-r--r-- | include/linux/eventpoll.h | 2 | ||||
-rw-r--r-- | include/uapi/linux/eventpoll.h | 1 |
3 files changed, 14 insertions, 2 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index daa9885d9c2b..ec7ffce8265a 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -2183,6 +2183,17 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds, */ ep = f.file->private_data; + /* + * Handle EPOLL_CTL_MIN_WAIT upfront as we don't need to care about + * the fd being passed in. + */ + if (op == EPOLL_CTL_MIN_WAIT) { + /* return old value */ + error = ep->min_wait_ts; + ep->min_wait_ts = epds->data; + goto error_fput; + } + /* Get the "struct file *" for the target file */ tf = fdget(fd); if (!tf.file) @@ -2315,7 +2326,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, { struct epoll_event epds; - if (ep_op_has_event(op) && + if ((ep_op_has_event(op) || op == EPOLL_CTL_MIN_WAIT) && copy_from_user(&epds, event, sizeof(struct epoll_event))) return -EFAULT; diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h index 3337745d81bd..cbef635cb7e4 100644 --- a/include/linux/eventpoll.h +++ b/include/linux/eventpoll.h @@ -59,7 +59,7 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds, /* Tells if the epoll_ctl(2) operation needs an event copy from userspace */ static inline int ep_op_has_event(int op) { - return op != EPOLL_CTL_DEL; + return op != EPOLL_CTL_DEL && op != EPOLL_CTL_MIN_WAIT; } #else diff --git a/include/uapi/linux/eventpoll.h b/include/uapi/linux/eventpoll.h index 8a3432d0f0dc..81ecb1ca36e0 100644 --- a/include/uapi/linux/eventpoll.h +++ b/include/uapi/linux/eventpoll.h @@ -26,6 +26,7 @@ #define EPOLL_CTL_ADD 1 #define EPOLL_CTL_DEL 2 #define EPOLL_CTL_MOD 3 +#define EPOLL_CTL_MIN_WAIT 4 /* Epoll event masks */ #define EPOLLIN (__force __poll_t)0x00000001 |