Merge branch 'i2c-embedded/for-next' of git://git.pengutronix.de/git/wsa/linux

[~andy/linux] / fs / eventpoll.c

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index eedec84c1809173eb4c627815ad70122de66eeb3..da72250ddc1cf2331336a23cbe8239bf880a10cf 100644 (file)
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -346,7 +346,7 @@ static inline struct epitem *ep_item_from_epqueue(poll_table *p)
 /* Tells if the epoll_ctl(2) operation needs an event copy from userspace */
 static inline int ep_op_has_event(int op)
 {
-       return op != EPOLL_CTL_DEL;
+       return op == EPOLL_CTL_ADD || op == EPOLL_CTL_MOD;
 }
 
 /* Initialize the poll safe wake up structure */
@@ -676,6 +676,34 @@ static int ep_remove(struct eventpoll *ep, struct epitem *epi)
        return 0;
 }
 
+/*
+ * Disables a "struct epitem" in the eventpoll set. Returns -EBUSY if the item
+ * had no event flags set, indicating that another thread may be currently
+ * handling that item's events (in the case that EPOLLONESHOT was being
+ * used). Otherwise a zero result indicates that the item has been disabled
+ * from receiving events. A disabled item may be re-enabled via
+ * EPOLL_CTL_MOD. Must be called with "mtx" held.
+ */
+static int ep_disable(struct eventpoll *ep, struct epitem *epi)
+{
+       int result = 0;
+       unsigned long flags;
+
+       spin_lock_irqsave(&ep->lock, flags);
+       if (epi->event.events & ~EP_PRIVATE_BITS) {
+               if (ep_is_linked(&epi->rdllink))
+                       list_del_init(&epi->rdllink);
+               /* Ensure ep_poll_callback will not add epi back onto ready
+                  list: */
+               epi->event.events &= EP_PRIVATE_BITS;
+               }
+       else
+               result = -EBUSY;
+       spin_unlock_irqrestore(&ep->lock, flags);
+
+       return result;
+}
+
 static void ep_free(struct eventpoll *ep)
 {
        struct rb_node *rbp;
@@ -1020,8 +1048,6 @@ static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
        rb_insert_color(&epi->rbn, &ep->rbr);
 }
 
-
-
 #define PATH_ARR_SIZE 5
 /*
  * These are the number paths of length 1 to 5, that we are allowing to emanate
@@ -1787,6 +1813,12 @@ SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd,
                } else
                        error = -ENOENT;
                break;
+       case EPOLL_CTL_DISABLE:
+               if (epi)
+                       error = ep_disable(ep, epi);
+               else
+                       error = -ENOENT;
+               break;
        }
        mutex_unlock(&ep->mtx);
 
@@ -1810,7 +1842,7 @@ SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
                int, maxevents, int, timeout)
 {
        int error;
-       struct file *file;
+       struct fd f;
        struct eventpoll *ep;
 
        /* The maximum number of event must be greater than zero */
@@ -1818,38 +1850,33 @@ SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events,
                return -EINVAL;
 
        /* Verify that the area passed by the user is writeable */
-       if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event))) {
-               error = -EFAULT;
-               goto error_return;
-       }
+       if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event)))
+               return -EFAULT;
 
        /* Get the "struct file *" for the eventpoll file */
-       error = -EBADF;
-       file = fget(epfd);
-       if (!file)
-               goto error_return;
+       f = fdget(epfd);
+       if (!f.file)
+               return -EBADF;
 
        /*
         * We have to check that the file structure underneath the fd
         * the user passed to us _is_ an eventpoll file.
         */
        error = -EINVAL;
-       if (!is_file_epoll(file))
+       if (!is_file_epoll(f.file))
                goto error_fput;
 
        /*
         * At this point it is safe to assume that the "private_data" contains
         * our own data structure.
         */
-       ep = file->private_data;
+       ep = f.file->private_data;
 
        /* Time to fish for events ... */
        error = ep_poll(ep, events, maxevents, timeout);
 
 error_fput:
-       fput(file);
-error_return:
-
+       fdput(f);
        return error;
 }