[libvirt] PATCH: 3/4: Fix handling of deleted file handles
Daniel P. Berrange
berrange at redhat.com
Mon May 11 11:21:40 UTC 2009
This patch fixes handling of deleted file handles. First of all it reverts
the patch http://www.redhat.com/archives/libvir-list/2009-March/msg00246.html
As an alternative solution to that original problem, the first thing that
virEventRunOnce() does, is to purge all timers/watches which were marked as
deleted. This deals with deletes that happen between invocations of the
virEventRunOnce() method. It also ensures that when going into poll(), all
the registered timers/watches are live. This guarentees that array indexes
match up between the poll FD array and our list of watches. Then during
the dispatch of FDs, we have a simpler check to skip invocation of file
handles / timers marked as deleted.
Daniel
diff -r 63d6824fe2a3 qemud/event.c
--- a/qemud/event.c Fri May 08 16:06:40 2009 +0100
+++ b/qemud/event.c Fri May 08 16:07:04 2009 +0100
@@ -313,7 +313,7 @@ static int virEventCalculateTimeout(int
EVENT_DEBUG("Calculate expiry of %d timers", eventLoop.timeoutsCount);
/* Figure out if we need a timeout */
for (i = 0 ; i < eventLoop.timeoutsCount ; i++) {
- if (eventLoop.timeouts[i].deleted || eventLoop.timeouts[i].frequency < 0)
+ if (eventLoop.timeouts[i].frequency < 0)
continue;
EVENT_DEBUG("Got a timeout scheduled for %llu", eventLoop.timeouts[i].expiresAt);
@@ -350,32 +350,26 @@ static int virEventCalculateTimeout(int
* file handles. The caller must free the returned data struct
* returns: the pollfd array, or NULL on error
*/
-static int virEventMakePollFDs(struct pollfd **retfds) {
+static struct pollfd *virEventMakePollFDs(void) {
struct pollfd *fds;
- int i, nfds = 0;
+ int i;
+
+ /* Setup the poll file handle data structs */
+ if (VIR_ALLOC_N(fds, eventLoop.handlesCount) < 0)
+ return NULL;
for (i = 0 ; i < eventLoop.handlesCount ; i++) {
- if (eventLoop.handles[i].deleted)
- continue;
- nfds++;
- }
- *retfds = NULL;
- /* Setup the poll file handle data structs */
- if (VIR_ALLOC_N(fds, nfds) < 0)
- return -1;
-
- for (i = 0, nfds = 0 ; i < eventLoop.handlesCount ; i++) {
- if (eventLoop.handles[i].deleted)
- continue;
- fds[nfds].fd = eventLoop.handles[i].fd;
- fds[nfds].events = eventLoop.handles[i].events;
- fds[nfds].revents = 0;
+ EVENT_DEBUG("Prepare n=%d w=%d, f=%d e=%d", i,
+ eventLoop.handles[i].watch,
+ eventLoop.handles[i].fd,
+ eventLoop.handles[i].events);
+ fds[i].fd = eventLoop.handles[i].fd;
+ fds[i].events = eventLoop.handles[i].events;
+ fds[i].revents = 0;
//EVENT_DEBUG("Wait for %d %d", eventLoop.handles[i].fd, eventLoop.handles[i].events);
- nfds++;
}
- *retfds = fds;
- return nfds;
+ return fds;
}
@@ -435,26 +429,30 @@ static int virEventDispatchTimeouts(void
* Returns 0 upon success, -1 if an error occurred
*/
static int virEventDispatchHandles(int nfds, struct pollfd *fds) {
- int i, n;
+ int i;
- for (i = 0, n = 0 ; i < eventLoop.handlesCount && n < nfds ; i++) {
+ /* NB, use nfds not eventLoop.handlesCount, because new
+ * fds might be added on end of list, and they're not
+ * in the fds array we've got */
+ for (i = 0 ; i < nfds ; i++) {
if (eventLoop.handles[i].deleted) {
- EVENT_DEBUG("Skip deleted %d", eventLoop.handles[i].fd);
+ EVENT_DEBUG("Skip deleted n=%d w=%d f=%d", i,
+ eventLoop.handles[i].watch, eventLoop.handles[i].fd);
continue;
}
- if (fds[n].revents) {
+ if (fds[i].revents) {
virEventHandleCallback cb = eventLoop.handles[i].cb;
void *opaque = eventLoop.handles[i].opaque;
- int hEvents = virPollEventToEventHandleType(fds[n].revents);
- EVENT_DEBUG("Dispatch %d %d %p", fds[n].fd,
- fds[n].revents, eventLoop.handles[i].opaque);
+ int hEvents = virPollEventToEventHandleType(fds[i].revents);
+ EVENT_DEBUG("Dispatch n=%d f=%d w=%d e=%d %p", i,
+ fds[i].fd, eventLoop.handles[i].watch,
+ fds[i].revents, eventLoop.handles[i].opaque);
virEventUnlock();
(cb)(eventLoop.handles[i].watch,
- fds[n].fd, hEvents, opaque);
+ fds[i].fd, hEvents, opaque);
virEventLock();
}
- n++;
}
return 0;
@@ -545,22 +543,21 @@ static int virEventCleanupHandles(void)
* at least one file handle has an event, or a timer expires
*/
int virEventRunOnce(void) {
- struct pollfd *fds;
+ struct pollfd *fds = NULL;
int ret, timeout, nfds;
virEventLock();
eventLoop.running = 1;
eventLoop.leader = pthread_self();
- if ((nfds = virEventMakePollFDs(&fds)) < 0) {
- virEventUnlock();
- return -1;
- }
- if (virEventCalculateTimeout(&timeout) < 0) {
- VIR_FREE(fds);
- virEventUnlock();
- return -1;
- }
+ if (virEventCleanupTimeouts() < 0 ||
+ virEventCleanupHandles() < 0)
+ goto error;
+
+ if (!(fds = virEventMakePollFDs()) ||
+ virEventCalculateTimeout(&timeout) < 0)
+ goto error;
+ nfds = eventLoop.handlesCount;
virEventUnlock();
@@ -572,38 +569,31 @@ int virEventRunOnce(void) {
if (errno == EINTR) {
goto retry;
}
- VIR_FREE(fds);
- return -1;
+ goto error_unlocked;
}
virEventLock();
- if (virEventDispatchTimeouts() < 0) {
- VIR_FREE(fds);
- virEventUnlock();
- return -1;
- }
+ if (virEventDispatchTimeouts() < 0)
+ goto error;
if (ret > 0 &&
- virEventDispatchHandles(nfds, fds) < 0) {
- VIR_FREE(fds);
- virEventUnlock();
- return -1;
- }
- VIR_FREE(fds);
+ virEventDispatchHandles(nfds, fds) < 0)
+ goto error;
- if (virEventCleanupTimeouts() < 0) {
- virEventUnlock();
- return -1;
- }
-
- if (virEventCleanupHandles() < 0) {
- virEventUnlock();
- return -1;
- }
+ if (virEventCleanupTimeouts() < 0 ||
+ virEventCleanupHandles() < 0)
+ goto error;
eventLoop.running = 0;
virEventUnlock();
+ VIR_FREE(fds);
return 0;
+
+error:
+ virEventUnlock();
+error_unlocked:
+ VIR_FREE(fds);
+ return -1;
}
static void virEventHandleWakeup(int watch ATTRIBUTE_UNUSED,
--
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