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Diffstat (limited to 'fs/eventpoll.c')
-rw-r--r--fs/eventpoll.c87
1 files changed, 56 insertions, 31 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 67a395039268..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)
{
@@ -2074,27 +2068,28 @@ SYSCALL_DEFINE1(epoll_create, int, size)
return do_epoll_create(0);
}
-/*
- * The following function implements the controller interface for
- * the eventpoll file that enables the insertion/removal/change of
- * file descriptors inside the interest set.
- */
-SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
- struct epoll_event __user *, event)
+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;
struct fd f, tf;
struct eventpoll *ep;
struct epitem *epi;
- struct epoll_event epds;
struct eventpoll *tep = NULL;
- error = -EFAULT;
- if (ep_op_has_event(op) &&
- copy_from_user(&epds, event, sizeof(struct epoll_event)))
- goto error_return;
-
error = -EBADF;
f = fdget(epfd);
if (!f.file)
@@ -2112,7 +2107,7 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
/* Check if EPOLLWAKEUP is allowed */
if (ep_op_has_event(op))
- ep_take_care_of_epollwakeup(&epds);
+ ep_take_care_of_epollwakeup(epds);
/*
* We have to check that the file structure underneath the file descriptor
@@ -2128,11 +2123,11 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
* so EPOLLEXCLUSIVE is not allowed for a EPOLL_CTL_MOD operation.
* Also, we do not currently supported nested exclusive wakeups.
*/
- if (ep_op_has_event(op) && (epds.events & EPOLLEXCLUSIVE)) {
+ if (ep_op_has_event(op) && (epds->events & EPOLLEXCLUSIVE)) {
if (op == EPOLL_CTL_MOD)
goto error_tgt_fput;
if (op == EPOLL_CTL_ADD && (is_file_epoll(tf.file) ||
- (epds.events & ~EPOLLEXCLUSIVE_OK_BITS)))
+ (epds->events & ~EPOLLEXCLUSIVE_OK_BITS)))
goto error_tgt_fput;
}
@@ -2157,13 +2152,17 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
* 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) {
@@ -2173,10 +2172,19 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
} 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;
+ }
}
}
}
@@ -2192,8 +2200,8 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
switch (op) {
case EPOLL_CTL_ADD:
if (!epi) {
- epds.events |= EPOLLERR | EPOLLHUP;
- error = ep_insert(ep, &epds, tf.file, fd, full_check);
+ epds->events |= EPOLLERR | EPOLLHUP;
+ error = ep_insert(ep, epds, tf.file, fd, full_check);
} else
error = -EEXIST;
if (full_check)
@@ -2208,8 +2216,8 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
case EPOLL_CTL_MOD:
if (epi) {
if (!(epi->event.events & EPOLLEXCLUSIVE)) {
- epds.events |= EPOLLERR | EPOLLHUP;
- error = ep_modify(ep, epi, &epds);
+ epds->events |= EPOLLERR | EPOLLHUP;
+ error = ep_modify(ep, epi, epds);
}
} else
error = -ENOENT;
@@ -2232,6 +2240,23 @@ error_return:
}
/*
+ * The following function implements the controller interface for
+ * the eventpoll file that enables the insertion/removal/change of
+ * file descriptors inside the interest set.
+ */
+SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
+ struct epoll_event __user *, event)
+{
+ struct epoll_event epds;
+
+ if (ep_op_has_event(op) &&
+ copy_from_user(&epds, event, sizeof(struct epoll_event)))
+ return -EFAULT;
+
+ return do_epoll_ctl(epfd, op, fd, &epds, false);
+}
+
+/*
* Implement the event wait interface for the eventpoll file. It is the kernel
* part of the user space epoll_wait(2).
*/