diff options
| -rw-r--r-- | fs/eventpoll.c | 80 |
1 files changed, 35 insertions, 45 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index dc15bb02ee2a..1e048144f17c 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -276,9 +276,6 @@ static DEFINE_MUTEX(epmutex); /* Used to check for epoll file descriptor inclusion loops */ static struct nested_calls poll_loop_ncalls; -/* Used to call file's f_op->poll() under the nested calls boundaries */ -static struct nested_calls poll_readywalk_ncalls; - /* Slab cache used to allocate "struct epitem" */ static struct kmem_cache *epi_cache __read_mostly; @@ -867,11 +864,33 @@ static int ep_eventpoll_release(struct inode *inode, struct file *file) return 0; } -static inline unsigned int ep_item_poll(struct epitem *epi, poll_table *pt) +static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head, + void *priv); +static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, + poll_table *pt); + +/* + * Differs from ep_eventpoll_poll() in that internal callers already have + * the ep->mtx so we need to start from depth=1, such that mutex_lock_nested() + * is correctly annotated. + */ +static unsigned int ep_item_poll(struct epitem *epi, poll_table *pt, int depth) { + struct eventpoll *ep; + bool locked; + pt->_key = epi->event.events; + if (!is_file_epoll(epi->ffd.file)) + return epi->ffd.file->f_op->poll(epi->ffd.file, pt) & + epi->event.events; - return epi->ffd.file->f_op->poll(epi->ffd.file, pt) & epi->event.events; + ep = epi->ffd.file->private_data; + poll_wait(epi->ffd.file, &ep->poll_wait, pt); + locked = pt && (pt->_qproc == ep_ptable_queue_proc); + + return ep_scan_ready_list(epi->ffd.file->private_data, + ep_read_events_proc, &depth, depth, + locked) & epi->event.events; } static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head, @@ -879,13 +898,15 @@ static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head, { struct epitem *epi, *tmp; poll_table pt; + int depth = *(int *)priv; init_poll_funcptr(&pt, NULL); + depth++; list_for_each_entry_safe(epi, tmp, head, rdllink) { - if (ep_item_poll(epi, &pt)) + if (ep_item_poll(epi, &pt, depth)) { return POLLIN | POLLRDNORM; - else { + } else { /* * Item has been dropped into the ready list by the poll * callback, but it's not actually ready, as far as @@ -899,48 +920,20 @@ static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head, return 0; } -static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, - poll_table *pt); - -struct readyevents_arg { - struct eventpoll *ep; - bool locked; -}; - -static int ep_poll_readyevents_proc(void *priv, void *cookie, int call_nests) -{ - struct readyevents_arg *arg = priv; - - return ep_scan_ready_list(arg->ep, ep_read_events_proc, NULL, - call_nests + 1, arg->locked); -} - static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait) { - int pollflags; struct eventpoll *ep = file->private_data; - struct readyevents_arg arg; - - /* - * During ep_insert() we already hold the ep->mtx for the tfile. - * Prevent re-aquisition. - */ - arg.locked = wait && (wait->_qproc == ep_ptable_queue_proc); - arg.ep = ep; + int depth = 0; /* Insert inside our poll wait queue */ poll_wait(file, &ep->poll_wait, wait); /* * Proceed to find out if wanted events are really available inside - * the ready list. This need to be done under ep_call_nested() - * supervision, since the call to f_op->poll() done on listed files - * could re-enter here. + * the ready list. */ - pollflags = ep_call_nested(&poll_readywalk_ncalls, EP_MAX_NESTS, - ep_poll_readyevents_proc, &arg, ep, current); - - return pollflags != -1 ? pollflags : 0; + return ep_scan_ready_list(ep, ep_read_events_proc, + &depth, depth, false); } #ifdef CONFIG_PROC_FS @@ -1459,7 +1452,7 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event, * this operation completes, the poll callback can start hitting * the new item. */ - revents = ep_item_poll(epi, &epq.pt); + revents = ep_item_poll(epi, &epq.pt, 1); /* * We have to check if something went wrong during the poll wait queue @@ -1593,7 +1586,7 @@ static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_even * Get current event bits. We can safely use the file* here because * its usage count has been increased by the caller of this function. */ - revents = ep_item_poll(epi, &pt); + revents = ep_item_poll(epi, &pt, 1); /* * If the item is "hot" and it is not registered inside the ready @@ -1661,7 +1654,7 @@ static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head, list_del_init(&epi->rdllink); - revents = ep_item_poll(epi, &pt); + revents = ep_item_poll(epi, &pt, 1); /* * If the event mask intersect the caller-requested one, @@ -2307,9 +2300,6 @@ static int __init eventpoll_init(void) ep_nested_calls_init(&poll_safewake_ncalls); #endif - /* Initialize the structure used to perform file's f_op->poll() calls */ - ep_nested_calls_init(&poll_readywalk_ncalls); - /* * We can have many thousands of epitems, so prevent this from * using an extra cache line on 64-bit (and smaller) CPUs |