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authorJeremy Allison <jra@samba.org>2013-02-14 13:50:56 -0800
committerJeremy Allison <jra@samba.org>2013-03-01 12:00:59 -0800
commite4b496cc096e1caabdaee646c162f0ba8cfac39c (patch)
tree1ba832c2a0ecc9387e24317c65d60a9e483440e6
parent7ef688c1dd797b1d108afe02c4b803bab01988ab (diff)
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tevent: Start to fix the epoll backend to support 2 fd events on the same fd correctly.
Add a utility function epoll_add_multiplex_fd() and a new flag EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX. This will be called by epoll_add_event() to merge two fde events with the same file descriptor. Signed-off-by: Jeremy Allison <jra@samba.org> Signed-off-by: Stefan Metzmacher <metze@samba.org> Reviewed-by: Stefan Metzmacher <metze@samba.org>
-rw-r--r--lib/tevent/tevent_epoll.c97
1 files changed, 96 insertions, 1 deletions
diff --git a/lib/tevent/tevent_epoll.c b/lib/tevent/tevent_epoll.c
index adea677096..c2b743dcd1 100644
--- a/lib/tevent/tevent_epoll.c
+++ b/lib/tevent/tevent_epoll.c
@@ -4,7 +4,8 @@
main select loop and event handling - epoll implementation
Copyright (C) Andrew Tridgell 2003-2005
- Copyright (C) Stefan Metzmacher 2005-2009
+ Copyright (C) Stefan Metzmacher 2005-2013
+ Copyright (C) Jeremy Allison 2013
** NOTE! The following LGPL license applies to the tevent
** library. This does NOT imply that all of Samba is released
@@ -48,6 +49,7 @@ struct epoll_event_context {
#define EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT (1<<0)
#define EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR (1<<1)
#define EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR (1<<2)
+#define EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX (1<<3)
#ifdef TEST_PANIC_FALLBACK
@@ -264,6 +266,99 @@ static void epoll_check_reopen(struct epoll_event_context *epoll_ev)
}
/*
+ epoll cannot add the same file descriptor twice, once
+ with read, once with write which is allowed by the
+ tevent backend. Multiplex the existing fde, flag it
+ as such so we can search for the correct fde on
+ event triggering.
+*/
+
+static int epoll_add_multiplex_fd(struct epoll_event_context *epoll_ev,
+ struct tevent_fd *add_fde)
+{
+ struct epoll_event event;
+ struct tevent_fd *mpx_fde;
+ int ret;
+
+ /* Find the existing fde that caused the EEXIST error. */
+ for (mpx_fde = epoll_ev->ev->fd_events; mpx_fde; mpx_fde = mpx_fde->next) {
+ if (mpx_fde->fd != add_fde->fd) {
+ continue;
+ }
+
+ if (mpx_fde == add_fde) {
+ continue;
+ }
+
+ break;
+ }
+ if (mpx_fde == NULL) {
+ tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
+ "can't find multiplex fde for fd[%d]",
+ add_fde->fd);
+ return -1;
+ }
+
+ if (mpx_fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX) {
+ /* Logic error. Can't have more than 2 multiplexed fde's. */
+ tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
+ "multiplex fde for fd[%d] is already multiplexed\n",
+ mpx_fde->fd);
+ return -1;
+ }
+
+ /*
+ * The multiplex fde must have the same fd, and also
+ * already have an epoll event attached.
+ */
+ if (!(mpx_fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT)) {
+ /* Logic error. Can't have more than 2 multiplexed fde's. */
+ tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
+ "multiplex fde for fd[%d] has no event\n",
+ mpx_fde->fd);
+ return -1;
+ }
+
+ /* Modify the mpx_fde to add in the new flags. */
+ ZERO_STRUCT(event);
+ event.events = epoll_map_flags(mpx_fde->flags);
+ event.events |= epoll_map_flags(add_fde->flags);
+ event.data.ptr = mpx_fde;
+ ret = epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_MOD, mpx_fde->fd, &event);
+ if (ret != 0 && errno == EBADF) {
+ tevent_debug(epoll_ev->ev, TEVENT_DEBUG_ERROR,
+ "EPOLL_CTL_MOD EBADF for "
+ "add_fde[%p] mpx_fde[%p] fd[%d] - disabling\n",
+ add_fde, mpx_fde, add_fde->fd);
+ DLIST_REMOVE(epoll_ev->ev->fd_events, mpx_fde);
+ mpx_fde->event_ctx = NULL;
+ DLIST_REMOVE(epoll_ev->ev->fd_events, add_fde);
+ add_fde->event_ctx = NULL;
+ return 0;
+ } else if (ret != 0) {
+ return ret;
+ }
+
+ /*
+ * Make each fde->additional_data pointers point at each other
+ * so we can look them up from each other. They are now paired.
+ */
+ mpx_fde->additional_data = (struct tevent_fd *)add_fde;
+ add_fde->additional_data = (struct tevent_fd *)mpx_fde;
+
+ /* Now flag both fde's as being multiplexed. */
+ mpx_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX;
+ add_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_MPX;
+
+ /* we need to keep the GOT_ERROR flag */
+ if (mpx_fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR) {
+ add_fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
+ }
+
+ return 0;
+}
+
+/*
add the epoll event to the given fd_event
*/
static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)