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authorJens Axboe <axboe@kernel.dk>2020-01-09 01:05:37 +0300
committerJens Axboe <axboe@kernel.dk>2020-01-30 01:45:47 +0300
commit39220e8d4a2aaab045ea03cc16d737e85d0817bf (patch)
tree2f632dd3e4f97820a9bb9de3bc18682c72ba5015
parent58e41a44c488f3e9601fd8150f58377ef8f44889 (diff)
downloadlinux-39220e8d4a2aaab045ea03cc16d737e85d0817bf.tar.xz
eventpoll: support non-blocking do_epoll_ctl() calls
Also make it available outside of epoll, along with the helper that decides if we need to copy the passed in epoll_event. Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/eventpoll.c46
-rw-r--r--include/linux/eventpoll.h9
2 files changed, 42 insertions, 13 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index cd848e8d08e2..b041b66002db 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -354,12 +354,6 @@ static inline struct epitem *ep_item_from_epqueue(poll_table *p)
return container_of(p, struct ep_pqueue, pt)->epi;
}
-/* 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;
-}
-
/* Initialize the poll safe wake up structure */
static void ep_nested_calls_init(struct nested_calls *ncalls)
{
@@ -2074,7 +2068,20 @@ SYSCALL_DEFINE1(epoll_create, int, size)
return do_epoll_create(0);
}
-static int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds)
+static inline int epoll_mutex_lock(struct mutex *mutex, int depth,
+ bool nonblock)
+{
+ if (!nonblock) {
+ mutex_lock_nested(mutex, depth);
+ return 0;
+ }
+ if (mutex_trylock(mutex))
+ return 0;
+ return -EAGAIN;
+}
+
+int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
+ bool nonblock)
{
int error;
int full_check = 0;
@@ -2145,13 +2152,17 @@ static int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds)
* deep wakeup paths from forming in parallel through multiple
* EPOLL_CTL_ADD operations.
*/
- mutex_lock_nested(&ep->mtx, 0);
+ error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
+ if (error)
+ goto error_tgt_fput;
if (op == EPOLL_CTL_ADD) {
if (!list_empty(&f.file->f_ep_links) ||
is_file_epoll(tf.file)) {
- full_check = 1;
mutex_unlock(&ep->mtx);
- mutex_lock(&epmutex);
+ error = epoll_mutex_lock(&epmutex, 0, nonblock);
+ if (error)
+ goto error_tgt_fput;
+ full_check = 1;
if (is_file_epoll(tf.file)) {
error = -ELOOP;
if (ep_loop_check(ep, tf.file) != 0) {
@@ -2161,10 +2172,19 @@ static int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds)
} else
list_add(&tf.file->f_tfile_llink,
&tfile_check_list);
- mutex_lock_nested(&ep->mtx, 0);
+ error = epoll_mutex_lock(&ep->mtx, 0, nonblock);
+ if (error) {
+out_del:
+ list_del(&tf.file->f_tfile_llink);
+ goto error_tgt_fput;
+ }
if (is_file_epoll(tf.file)) {
tep = tf.file->private_data;
- mutex_lock_nested(&tep->mtx, 1);
+ error = epoll_mutex_lock(&tep->mtx, 1, nonblock);
+ if (error) {
+ mutex_unlock(&ep->mtx);
+ goto out_del;
+ }
}
}
}
@@ -2233,7 +2253,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
copy_from_user(&epds, event, sizeof(struct epoll_event)))
return -EFAULT;
- return do_epoll_ctl(epfd, op, fd, &epds);
+ return do_epoll_ctl(epfd, op, fd, &epds, false);
}
/*
diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h
index bc6d79b00c4e..8f000fada5a4 100644
--- a/include/linux/eventpoll.h
+++ b/include/linux/eventpoll.h
@@ -61,6 +61,15 @@ static inline void eventpoll_release(struct file *file)
eventpoll_release_file(file);
}
+int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
+ bool nonblock);
+
+/* 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;
+}
+
#else
static inline void eventpoll_init_file(struct file *file) {}