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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 <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2020-09-02 11:55:09 -04:00
parent 80285b75c6
commit 364f374f22
1 changed files with 20 additions and 26 deletions
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46
fs/eventpoll.c
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@ -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 */