From 364f374f22ba1b049b17de602a8e5eceb1df4cef Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 2 Sep 2020 11:55:09 -0400 Subject: [PATCH] epoll: get rid of epitem->nwait we use it only to indicate allocation failures within queueing callback back to ep_insert(). Might as well use epq.epi for that reporting... Signed-off-by: Al Viro --- fs/eventpoll.c | 46 ++++++++++++++++++++-------------------------- 1 file changed, 20 insertions(+), 26 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index ae41868..44aca68 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -172,9 +172,6 @@ struct epitem { /* The file descriptor information this item refers to */ struct epoll_filefd ffd; - /* Number of active wait queue attached to poll operations */ - int nwait; - /* List containing poll wait queues */ struct eppoll_entry *pwqlist; @@ -351,12 +348,6 @@ static inline struct epitem *ep_item_from_wait(wait_queue_entry_t *p) return container_of(p, struct eppoll_entry, wait)->base; } -/* Get the "struct epitem" from an epoll queue wrapper */ -static inline struct epitem *ep_item_from_epqueue(poll_table *p) -{ - return container_of(p, struct ep_pqueue, pt)->epi; -} - /* Initialize the poll safe wake up structure */ static void ep_nested_calls_init(struct nested_calls *ncalls) { @@ -1307,24 +1298,28 @@ out_unlock: static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, poll_table *pt) { - struct epitem *epi = ep_item_from_epqueue(pt); + struct ep_pqueue *epq = container_of(pt, struct ep_pqueue, pt); + struct epitem *epi = epq->epi; struct eppoll_entry *pwq; - if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) { - init_waitqueue_func_entry(&pwq->wait, ep_poll_callback); - pwq->whead = whead; - pwq->base = epi; - if (epi->event.events & EPOLLEXCLUSIVE) - add_wait_queue_exclusive(whead, &pwq->wait); - else - add_wait_queue(whead, &pwq->wait); - pwq->next = epi->pwqlist; - epi->pwqlist = pwq; - epi->nwait++; - } else { - /* We have to signal that an error occurred */ - epi->nwait = -1; + if (unlikely(!epi)) // an earlier allocation has failed + return; + + pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL); + if (unlikely(!pwq)) { + epq->epi = NULL; + return; } + + init_waitqueue_func_entry(&pwq->wait, ep_poll_callback); + pwq->whead = whead; + pwq->base = epi; + if (epi->event.events & EPOLLEXCLUSIVE) + add_wait_queue_exclusive(whead, &pwq->wait); + else + add_wait_queue(whead, &pwq->wait); + pwq->next = epi->pwqlist; + epi->pwqlist = pwq; } static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi) @@ -1510,7 +1505,6 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, epi->ep = ep; ep_set_ffd(&epi->ffd, tfile, fd); epi->event = *event; - epi->nwait = 0; epi->next = EP_UNACTIVE_PTR; if (epi->event.events & EPOLLWAKEUP) { error = ep_create_wakeup_source(epi); @@ -1555,7 +1549,7 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, * high memory pressure. */ error = -ENOMEM; - if (epi->nwait < 0) + if (!epq.epi) goto error_unregister; /* We have to drop the new item inside our item list to keep track of it */ -- 2.7.4