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Fix /dev/devctl's implementation of poll. We should only be setting

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the poll bits when there's actually something in the queue.
Otherwise, select always returned '2' when there were no items to be
read, and '3' when there were.  This would preclude being able to read
in a threaded (libc_r) program, as well as checking to see if there
were pending events or not.
This commit is contained in:
Warner Losh 2003-04-21 05:58:51 +00:00
parent 61a0da1de5
commit e22b0bf4b8
1 changed files with 5 additions and 11 deletions
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16
sys/kern/subr_bus.c
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@ -353,21 +353,15 @@ devpoll(dev_t dev, int events, d_thread_t *td)
{
int revents = 0;
if (events & (POLLIN | POLLRDNORM))
revents |= events & (POLLIN | POLLRDNORM);
if (events & (POLLOUT | POLLWRNORM))
revents |= events & (POLLOUT | POLLWRNORM);
mtx_lock(&devsoftc.mtx);
if (events & POLLRDBAND)
if (events & (POLLIN | POLLRDNORM)) {
if (!TAILQ_EMPTY(&devsoftc.devq))
revents |= POLLRDBAND;
revents = events & (POLLIN | POLLRDNORM);
else
selrecord(td, &devsoftc.sel);
}
mtx_unlock(&devsoftc.mtx);
if (revents == 0)
selrecord(td, &devsoftc.sel);
return (revents);
}