Re: [PATCH] poll: Avoid extra wakeups in select/poll

Ingo Molnar
2009-04-29T09:17:49Z

* Eric Dumazet <dada1@cosmosbay.com> wrote:

> @@ -418,8 +429,16 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
> if (file) {
> f_op = file->f_op;
> mask = DEFAULT_POLLMASK;
> - if (f_op && f_op->poll)
> + if (f_op && f_op->poll) {
> + if (wait) {
> + wait->key = POLLEX_SET;
> + if (in & bit)
> + wait->key |= POLLIN_SET;
> + if (out & bit)
> + wait->key |= POLLOUT_SET;
> + }
> mask = (*f_op->poll)(file, retval ? NULL : wait);
> + }
> fput_light(file, fput_needed);
> if ((mask & POLLIN_SET) && (in & bit)) {
> res_in |= bit;

Please factor this whole 'if (file)' branch out into a helper.
Typical indentation levels go from 1 to 3 tabs - 4 should be avoided
if possible and 5 is pretty excessive already. This goes to eight.

Ingo