x86/debug: Only clear/set ->virtual_dr6 for userspace #DB

[linux-2.6-microblaze.git] / fs / eventpoll.c

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 8107e06..4df6112 100644 (file)
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -218,8 +218,7 @@ struct eventpoll {
        struct file *file;
 
        /* used to optimize loop detection check */
-       struct list_head visited_list_link;
-       int visited;
+       u64 gen;
 
 #ifdef CONFIG_NET_RX_BUSY_POLL
        /* used to track busy poll napi_id */
@@ -274,6 +273,8 @@ 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;
 
@@ -283,9 +284,6 @@ 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.
@@ -1450,7 +1448,7 @@ 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) {
@@ -1459,8 +1457,9 @@ 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(NULL, name);
+       take_dentry_name_snapshot(&n, epi->ffd.file->f_path.dentry);
+       ws = wakeup_source_register(NULL, n.name.name);
+       release_dentry_name_snapshot(&n);
 
        if (!ws)
                return -ENOMEM;
@@ -1522,6 +1521,22 @@ static int ep_insert(struct eventpoll *ep, const 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);
@@ -1544,22 +1559,6 @@ static int ep_insert(struct eventpoll *ep, const 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 */
        write_lock_irq(&ep->lock);
 
@@ -1588,6 +1587,8 @@ static int ep_insert(struct eventpoll *ep, const 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);
@@ -1595,9 +1596,6 @@ 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
@@ -1972,13 +1970,12 @@ 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_loop_check_proc, epi->ffd.file,
@@ -2019,18 +2016,8 @@ 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,
+       return ep_call_nested(&poll_loop_ncalls,
                              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)
@@ -2195,11 +2182,13 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
                goto error_tgt_fput;
        if (op == EPOLL_CTL_ADD) {
                if (!list_empty(&f.file->f_ep_links) ||
+                               ep->gen == loop_check_gen ||
                                                is_file_epoll(tf.file)) {
                        mutex_unlock(&ep->mtx);
                        error = epoll_mutex_lock(&epmutex, 0, nonblock);
                        if (error)
                                goto error_tgt_fput;
+                       loop_check_gen++;
                        full_check = 1;
                        if (is_file_epoll(tf.file)) {
                                error = -ELOOP;
@@ -2263,6 +2252,7 @@ int do_epoll_ctl(int epfd, int op, int fd, struct epoll_event *epds,
 error_tgt_fput:
        if (full_check) {
                clear_tfile_check_list();
+               loop_check_gen++;
                mutex_unlock(&epmutex);
        }