annotate poll(2) guts

struct pollfd contains two 16bit fields (mask and result) that encode
the POLL... bitmaps.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 10 insertions, 6 deletions

diff --git a/fs/select.c b/fs/select.c
index 8d6d47912134..b2deeb215dbe 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -803,9 +803,9 @@ struct poll_list {
  * pwait poll_table will be used by the fd-provided poll handler for waiting,
  * if pwait->_qproc is non-NULL.
  */
-static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait,
+static inline __poll_t do_pollfd(struct pollfd *pollfd, poll_table *pwait,
                                      bool *can_busy_poll,
-                                     unsigned int busy_flag)
+                                     __poll_t busy_flag)
 {
         __poll_t mask;
         int fd;
@@ -816,20 +816,24 @@ static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait,
                 struct fd f = fdget(fd);
                 mask = POLLNVAL;
                 if (f.file) {
+                        /* userland u16 ->events contains POLL... bitmap */
+                        __poll_t filter = (__force __poll_t)pollfd->events |
+                                                POLLERR | POLLHUP;
                         mask = DEFAULT_POLLMASK;
                         if (f.file->f_op->poll) {
-                                pwait->_key = pollfd->events|POLLERR|POLLHUP;
+                                pwait->_key = filter;
                                 pwait->_key |= busy_flag;
                                 mask = f.file->f_op->poll(f.file, pwait);
                                 if (mask & busy_flag)
                                         *can_busy_poll = true;
                         }
                         /* Mask out unneeded events. */
-                        mask &= pollfd->events | POLLERR | POLLHUP;
+                        mask &= filter;
                         fdput(f);
                 }
         }
-        pollfd->revents = mask;
+        /* ... and so does ->revents */
+        pollfd->revents = (__force u16)mask;
 
         return mask;
 }
@@ -841,7 +845,7 @@ static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
         ktime_t expire, *to = NULL;
         int timed_out = 0, count = 0;
         u64 slack = 0;
-        unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
+        __poll_t busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
         unsigned long busy_start = 0;
 
         /* Optimise the no-wait case */