diff options
Diffstat (limited to '')
| -rw-r--r-- | fs/eventpoll.c | 87 |
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). */ |