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authorAl Viro <viro@zeniv.linux.org.uk>2020-09-27 00:32:48 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2020-10-26 01:02:03 +0100
commitad9366b1361fd6ed3f85f670bdb4e8af039e450c (patch)
tree160daf678f3dda2995c8b67ce33194c60bedeb47 /fs/eventpoll.c
parentep_insert(): we only need tep->mtx around the insertion itself (diff)
downloadlinux-ad9366b1361fd6ed3f85f670bdb4e8af039e450c.tar.xz
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take the common part of ep_eventpoll_poll() and ep_item_poll() into helper
The only reason why ep_item_poll() can't simply call ep_eventpoll_poll() (or, better yet, call vfs_poll() in all cases) is that we need to tell lockdep how deep into the hierarchy of ->mtx we are. So let's add a variant of ep_eventpoll_poll() that would take depth explicitly and turn ep_eventpoll_poll() into wrapper for that. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/eventpoll.c')
-rw-r--r--fs/eventpoll.c57
1 files changed, 27 insertions, 30 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 3fbce9c91481..ee31ebe33150 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -732,6 +732,27 @@ static int ep_eventpoll_release(struct inode *inode, struct file *file)
static __poll_t ep_read_events_proc(struct eventpoll *ep, struct list_head *head,
int depth);
+static __poll_t __ep_eventpoll_poll(struct file *file, poll_table *wait, int depth)
+{
+ struct eventpoll *ep = file->private_data;
+ LIST_HEAD(txlist);
+ __poll_t res;
+
+ /* 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.
+ */
+ mutex_lock_nested(&ep->mtx, depth);
+ ep_start_scan(ep, &txlist);
+ res = ep_read_events_proc(ep, &txlist, depth + 1);
+ ep_done_scan(ep, &txlist);
+ mutex_unlock(&ep->mtx);
+ return res;
+}
+
/*
* 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()
@@ -740,22 +761,14 @@ static __poll_t ep_read_events_proc(struct eventpoll *ep, struct list_head *head
static __poll_t ep_item_poll(const struct epitem *epi, poll_table *pt,
int depth)
{
- struct eventpoll *ep;
- LIST_HEAD(txlist);
+ struct file *file = epi->ffd.file;
__poll_t res;
pt->_key = epi->event.events;
- if (!is_file_epoll(epi->ffd.file))
- return vfs_poll(epi->ffd.file, pt) & epi->event.events;
-
- ep = epi->ffd.file->private_data;
- poll_wait(epi->ffd.file, &ep->poll_wait, pt);
-
- mutex_lock_nested(&ep->mtx, depth);
- ep_start_scan(ep, &txlist);
- res = ep_read_events_proc(ep, &txlist, depth + 1);
- ep_done_scan(ep, &txlist);
- mutex_unlock(&ep->mtx);
+ if (!is_file_epoll(file))
+ res = vfs_poll(file, pt);
+ else
+ res = __ep_eventpoll_poll(file, pt, depth);
return res & epi->event.events;
}
@@ -786,23 +799,7 @@ static __poll_t ep_read_events_proc(struct eventpoll *ep, struct list_head *head
static __poll_t ep_eventpoll_poll(struct file *file, poll_table *wait)
{
- struct eventpoll *ep = file->private_data;
- LIST_HEAD(txlist);
- __poll_t res;
-
- /* 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.
- */
- mutex_lock(&ep->mtx);
- ep_start_scan(ep, &txlist);
- res = ep_read_events_proc(ep, &txlist, 1);
- ep_done_scan(ep, &txlist);
- mutex_unlock(&ep->mtx);
- return res;
+ return __ep_eventpoll_poll(file, wait, 0);
}
#ifdef CONFIG_PROC_FS