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| author | Al Viro <viro@zeniv.linux.org.uk> | 2020-09-26 23:29:02 +0300 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2020-10-26 03:01:56 +0300 |
| commit | 6a3890c474795a4a3536e0a0c39f526e415eb212 (patch) | |
| tree | 5d272fa32dd2dea231a765d1ab1639a3659cd3e5 /fs/eventpoll.c | |
| parent | 56c428cac5a2c361271370dde3a22cb640bc9934 (diff) | |
| download | linux-6a3890c474795a4a3536e0a0c39f526e415eb212.tar.xz | |
get rid of ep_push_nested()
The only remaining user is loop checking. But there we only need
to check that we have not walked into the epoll we are inserting
into - we are adding an edge to acyclic graph, so any loop being
created will have to pass through the source of that edge.
So we don't need that array of cookies - we have only one eventpoll
to watch out for. RIP ep_push_nested(), along with the cookies
array.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/eventpoll.c')
| -rw-r--r-- | fs/eventpoll.c | 29 |
1 files changed, 4 insertions, 25 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 9edea3933790..6b1990b8b9a0 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -254,8 +254,7 @@ static DEFINE_MUTEX(epmutex); static u64 loop_check_gen = 0; /* Used to check for epoll file descriptor inclusion loops */ -static void *cookies[EP_MAX_NESTS + 1]; -static int nesting; +static struct eventpoll *inserting_into; /* Slab cache used to allocate "struct epitem" */ static struct kmem_cache *epi_cache __read_mostly; @@ -424,21 +423,6 @@ static inline void ep_set_busy_poll_napi_id(struct epitem *epi) #endif /* CONFIG_NET_RX_BUSY_POLL */ -static bool ep_push_nested(void *cookie) -{ - int i; - - if (nesting > EP_MAX_NESTS) /* too deep nesting */ - return false; - - for (i = 0; i < nesting; i++) { - if (cookies[i] == cookie) /* loop detected */ - return false; - } - cookies[nesting++] = cookie; - return true; -} - /* * As described in commit 0ccf831cb lockdep: annotate epoll * the use of wait queues used by epoll is done in a very controlled @@ -1885,12 +1869,11 @@ static int ep_loop_check_proc(void *priv, void *cookie, int depth) ep_tovisit = epi->ffd.file->private_data; if (ep_tovisit->gen == loop_check_gen) continue; - if (!ep_push_nested(ep_tovisit)) { + if (ep_tovisit == inserting_into || depth > EP_MAX_NESTS) { error = -1; } else { error = ep_loop_check_proc(epi->ffd.file, ep_tovisit, depth + 1); - nesting--; } if (error != 0) break; @@ -1928,12 +1911,8 @@ static int ep_loop_check_proc(void *priv, void *cookie, int depth) */ static int ep_loop_check(struct eventpoll *ep, struct file *file) { - int err; - - ep_push_nested(ep); // can't fail - err = ep_loop_check_proc(file, ep, 0); - nesting--; - return err; + inserting_into = ep; + return ep_loop_check_proc(file, ep, 0); } static void clear_tfile_check_list(void) |