The patch titled
Subject: epoll: cleanup limit paths
has been added to the -mm tree. Its filename is
epoll-limit-paths-update.patch
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------------------------------------------------------
From: Jason Baron <jbaron@xxxxxxxxxx>
Subject: epoll: cleanup limit paths
Cleanups based on Andrew Morton's review:
https://lkml.org/lkml/2011/9/2/356
Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>
Cc: Nelson Elhage <nelhage@xxxxxxxxxxx>
Cc: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/eventpoll.c | 36 ++++++++++++++++++++++--------------
1 file changed, 22 insertions(+), 14 deletions(-)
diff -puN fs/eventpoll.c~epoll-limit-paths-update fs/eventpoll.c
--- a/fs/eventpoll.c~epoll-limit-paths-update
+++ a/fs/eventpoll.c
@@ -202,7 +202,7 @@ struct eventpoll {
/* used to optimize loop detection check */
int visited;
- struct list_head visitedllink;
+ struct list_head visited_list_link;
};
/* Wait structure used by the poll hooks */
@@ -262,10 +262,13 @@ static struct kmem_cache *epi_cache __re
static struct kmem_cache *pwq_cache __read_mostly;
/* Visited nodes during ep_loop_check(), so we can unset them when we finish */
-LIST_HEAD(visited_list);
+static LIST_HEAD(visited_list);
-/* Files with newly added links, which need a limit on emanating paths */
-LIST_HEAD(tfile_check_list);
+/*
+ * List of files with newly added links, where we may need to limit the number
+ * of emanating paths. Protected by the epmutex.
+ */
+static LIST_HEAD(tfile_check_list);
#ifdef CONFIG_SYSCTL
@@ -941,16 +944,19 @@ static void ep_rbtree_insert(struct even
#define PATH_ARR_SIZE 5
-/* These are the number paths of length 1 to 5, that we are allowing to emanate
+/*
+ * These are the number paths of length 1 to 5, that we are allowing to emanate
* from a single file of interest. For example, we allow 1000 paths of length
* 1, to emanate from each file of interest. This essentially represents the
* potential wakeup paths, which need to be limited in order to avoid massive
* uncontrolled wakeup storms. The common use case should be a single ep which
* is connected to n file sources. In this case each file source has 1 path
- * of length 1. Thus, the numbers below should be more than sufficient.
+ * of length 1. Thus, the numbers below should be more than sufficient. These
+ * path limits are enforced during an EPOLL_CTL_ADD operation, since a modify
+ * and delete can't add additional paths. Protected by the epmutex.
*/
-int path_limits[PATH_ARR_SIZE] = { 1000, 500, 100, 50, 10 };
-int path_count[PATH_ARR_SIZE];
+static const int path_limits[PATH_ARR_SIZE] = { 1000, 500, 100, 50, 10 };
+static int path_count[PATH_ARR_SIZE];
static int path_count_inc(int nests)
{
@@ -1396,7 +1402,7 @@ static int ep_loop_check_proc(void *priv
mutex_lock_nested(&ep->mtx, call_nests + 1);
ep->visited = 1;
- list_add(&ep->visitedllink, &visited_list);
+ list_add(&ep->visited_list_link, &visited_list);
for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
epi = rb_entry(rbp, struct epitem, rbn);
if (unlikely(is_file_epoll(epi->ffd.file))) {
@@ -1409,12 +1415,13 @@ static int ep_loop_check_proc(void *priv
if (error != 0)
break;
} else {
- /* if we've reached a file that is not associated with
- * an ep, then then we need to check if the newly added
+ /*
+ * If we've reached a file that is not associated with
+ * an ep, then we need to check if the newly added
* links are going to add too many wakeup paths. We do
* this by adding it to the tfile_check_list, if it's
* not already there, and calling reverse_path_check()
- * during ep_insert()
+ * during ep_insert().
*/
if (list_empty(&epi->ffd.file->f_tfile_llink))
list_add(&epi->ffd.file->f_tfile_llink,
@@ -1445,9 +1452,10 @@ static int ep_loop_check(struct eventpol
ret = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
ep_loop_check_proc, file, ep, current);
/* clear visited list */
- list_for_each_entry_safe(ep_cur, ep_next, &visited_list, visitedllink) {
+ list_for_each_entry_safe(ep_cur, ep_next, &visited_list,
+ visited_list_link) {
ep_cur->visited = 0;
- list_del(&ep_cur->visitedllink);
+ list_del(&ep_cur->visited_list_link);
}
return ret;
}
_
Subject: Subject: epoll: cleanup limit paths
Patches currently in -mm which might be from jbaron@xxxxxxxxxx are
origin.patch
epoll-limit-paths.patch
epoll-limit-paths-update.patch
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