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Diffstat (limited to 'fs/eventpoll.c')
-rw-r--r--fs/eventpoll.c94
1 files changed, 43 insertions, 51 deletions
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index c291bf61afb9..c9feb119aa47 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -223,8 +223,7 @@ struct eventpoll {
struct file *file;
/* used to optimize loop detection check */
- int visited;
- struct list_head visited_list_link;
+ u64 gen;
#ifdef CONFIG_NET_RX_BUSY_POLL
/* used to track busy poll napi_id */
@@ -273,6 +272,8 @@ static long max_user_watches __read_mostly;
*/
static DEFINE_MUTEX(epmutex);
+static u64 loop_check_gen = 0;
+
/* Used to check for epoll file descriptor inclusion loops */
static struct nested_calls poll_loop_ncalls;
@@ -288,9 +289,6 @@ static struct kmem_cache *epi_cache __read_mostly;
/* Slab cache used to allocate "struct eppoll_entry" */
static struct kmem_cache *pwq_cache __read_mostly;
-/* Visited nodes during ep_loop_check(), so we can unset them when we finish */
-static LIST_HEAD(visited_list);
-
/*
* List of files with newly added links, where we may need to limit the number
* of emanating paths. Protected by the epmutex.
@@ -1391,7 +1389,7 @@ static int reverse_path_check(void)
static int ep_create_wakeup_source(struct epitem *epi)
{
- const char *name;
+ struct name_snapshot n;
struct wakeup_source *ws;
if (!epi->ep->ws) {
@@ -1400,8 +1398,9 @@ static int ep_create_wakeup_source(struct epitem *epi)
return -ENOMEM;
}
- name = epi->ffd.file->f_path.dentry->d_name.name;
- ws = wakeup_source_register(name);
+ take_dentry_name_snapshot(&n, epi->ffd.file->f_path.dentry);
+ ws = wakeup_source_register(n.name);
+ release_dentry_name_snapshot(&n);
if (!ws)
return -ENOMEM;
@@ -1461,6 +1460,22 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
RCU_INIT_POINTER(epi->ws, NULL);
}
+ /* Add the current item to the list of active epoll hook for this file */
+ spin_lock(&tfile->f_lock);
+ list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links);
+ spin_unlock(&tfile->f_lock);
+
+ /*
+ * Add the current item to the RB tree. All RB tree operations are
+ * protected by "mtx", and ep_insert() is called with "mtx" held.
+ */
+ ep_rbtree_insert(ep, epi);
+
+ /* now check if we've created too many backpaths */
+ error = -EINVAL;
+ if (full_check && reverse_path_check())
+ goto error_remove_epi;
+
/* Initialize the poll table using the queue callback */
epq.epi = epi;
init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
@@ -1483,22 +1498,6 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
if (epi->nwait < 0)
goto error_unregister;
- /* Add the current item to the list of active epoll hook for this file */
- spin_lock(&tfile->f_lock);
- list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links);
- spin_unlock(&tfile->f_lock);
-
- /*
- * Add the current item to the RB tree. All RB tree operations are
- * protected by "mtx", and ep_insert() is called with "mtx" held.
- */
- ep_rbtree_insert(ep, epi);
-
- /* now check if we've created too many backpaths */
- error = -EINVAL;
- if (full_check && reverse_path_check())
- goto error_remove_epi;
-
/* We have to drop the new item inside our item list to keep track of it */
spin_lock_irqsave(&ep->lock, flags);
@@ -1527,6 +1526,8 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
return 0;
+error_unregister:
+ ep_unregister_pollwait(ep, epi);
error_remove_epi:
spin_lock(&tfile->f_lock);
list_del_rcu(&epi->fllink);
@@ -1534,9 +1535,6 @@ error_remove_epi:
rb_erase_cached(&epi->rbn, &ep->rbr);
-error_unregister:
- ep_unregister_pollwait(ep, epi);
-
/*
* We need to do this because an event could have been arrived on some
* allocated wait queue. Note that we don't care about the ep->ovflist
@@ -1878,13 +1876,12 @@ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests)
struct epitem *epi;
mutex_lock_nested(&ep->mtx, call_nests + 1);
- ep->visited = 1;
- list_add(&ep->visited_list_link, &visited_list);
+ ep->gen = loop_check_gen;
for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) {
epi = rb_entry(rbp, struct epitem, rbn);
if (unlikely(is_file_epoll(epi->ffd.file))) {
ep_tovisit = epi->ffd.file->private_data;
- if (ep_tovisit->visited)
+ if (ep_tovisit->gen == loop_check_gen)
continue;
error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
ep_loop_check_proc, epi->ffd.file,
@@ -1900,9 +1897,11 @@ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests)
* not already there, and calling reverse_path_check()
* during ep_insert().
*/
- if (list_empty(&epi->ffd.file->f_tfile_llink))
- list_add(&epi->ffd.file->f_tfile_llink,
- &tfile_check_list);
+ if (list_empty(&epi->ffd.file->f_tfile_llink)) {
+ if (get_file_rcu(epi->ffd.file))
+ list_add(&epi->ffd.file->f_tfile_llink,
+ &tfile_check_list);
+ }
}
}
mutex_unlock(&ep->mtx);
@@ -1923,18 +1922,8 @@ static int ep_loop_check_proc(void *priv, void *cookie, int call_nests)
*/
static int ep_loop_check(struct eventpoll *ep, struct file *file)
{
- int ret;
- struct eventpoll *ep_cur, *ep_next;
-
- ret = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS,
+ return 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,
- visited_list_link) {
- ep_cur->visited = 0;
- list_del(&ep_cur->visited_list_link);
- }
- return ret;
}
static void clear_tfile_check_list(void)
@@ -1946,6 +1935,7 @@ static void clear_tfile_check_list(void)
file = list_first_entry(&tfile_check_list, struct file,
f_tfile_llink);
list_del_init(&file->f_tfile_llink);
+ fput(file);
}
INIT_LIST_HEAD(&tfile_check_list);
}
@@ -2090,19 +2080,20 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
mutex_lock_nested(&ep->mtx, 0);
if (op == EPOLL_CTL_ADD) {
if (!list_empty(&f.file->f_ep_links) ||
+ ep->gen == loop_check_gen ||
is_file_epoll(tf.file)) {
full_check = 1;
mutex_unlock(&ep->mtx);
mutex_lock(&epmutex);
if (is_file_epoll(tf.file)) {
error = -ELOOP;
- if (ep_loop_check(ep, tf.file) != 0) {
- clear_tfile_check_list();
+ if (ep_loop_check(ep, tf.file) != 0)
goto error_tgt_fput;
- }
- } else
+ } else {
+ get_file(tf.file);
list_add(&tf.file->f_tfile_llink,
&tfile_check_list);
+ }
mutex_lock_nested(&ep->mtx, 0);
if (is_file_epoll(tf.file)) {
tep = tf.file->private_data;
@@ -2126,8 +2117,6 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
error = ep_insert(ep, &epds, tf.file, fd, full_check);
} else
error = -EEXIST;
- if (full_check)
- clear_tfile_check_list();
break;
case EPOLL_CTL_DEL:
if (epi)
@@ -2150,8 +2139,11 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
mutex_unlock(&ep->mtx);
error_tgt_fput:
- if (full_check)
+ if (full_check) {
+ clear_tfile_check_list();
+ loop_check_gen++;
mutex_unlock(&epmutex);
+ }
fdput(tf);
error_fput:
generated by cgit 1.2.3-korg (git 2.39.0) at 2024-04-19 18:59:58 +0000