Commit 8db165b3 authored May 16, 2013 by Stefan Hajnoczi Committed by Anthony Liguori May 16, 2013

main-loop: narrow win32 pollfds_fill() event bitmasks



pollfds_fill() and pollfds_poll() translate GPollFD to rfds/wfds/xfds
for sockets on win32.  select(2) is the underlying system call which is
used to monitor sockets for activity.

Currently file descriptors that monitor G_IO_ERR will be included in
both rfds and wfds.  As a result, select(2) will report writability on
file descriptors where we only really wanted to monitor readability
(with errors).

slirp_pollfds_poll() hit this issue: UDP sockets are blocking sockets so
we hang in sorecvfrom() when G_IO_ERR is set due to the socket being
writable (we only wanted to check for readability).

This patch fixes the slirp_pollfds_poll() hang.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1368718561-7816-2-git-send-email-stefanha@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

parent 6d46895b

main-loop.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -333,11 +333,11 @@ static int pollfds_fill(GArray pollfds, fd_set rfds, fd_set *wfds,
		GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
		int fd = pfd->fd;
		int events = pfd->events;
		if (events & (G_IO_IN \| G_IO_HUP \| G_IO_ERR)) {
		if (events & G_IO_IN) {
		FD_SET(fd, rfds);
		nfds = MAX(nfds, fd);
		}
		if (events & (G_IO_OUT \| G_IO_ERR)) {
		if (events & G_IO_OUT) {
		FD_SET(fd, wfds);
		nfds = MAX(nfds, fd);
		}
		@@ -360,10 +360,10 @@ static void pollfds_poll(GArray pollfds, int nfds, fd_set rfds,
		int revents = 0;

		if (FD_ISSET(fd, rfds)) {
		revents \|= G_IO_IN \| G_IO_HUP \| G_IO_ERR;
		revents \|= G_IO_IN;
		}
		if (FD_ISSET(fd, wfds)) {
		revents \|= G_IO_OUT \| G_IO_ERR;
		revents \|= G_IO_OUT;
		}
		if (FD_ISSET(fd, xfds)) {
		revents \|= G_IO_PRI;