Commit fb367937 authored by Al Viro's avatar Al Viro
Browse files

annotate poll(2) guts 



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

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 7594bf37

fs/select.c

+10 −6
Original line number Diff line number Diff line
@@ -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 */