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authorAndrew Tridgell <tridge@samba.org>2007-05-17 02:18:29 +0000
committerGerald (Jerry) Carter <jerry@samba.org>2007-10-10 14:52:31 -0500
commit87379e0d5877fc0d045e259d8428304a292088aa (patch)
tree114e9ec467956f4adf8ecab3264b289579ce9287
parent402218516a141722cf6cf42c29f15834122acbd7 (diff)
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r22959: cope with a rather interesting interaction between epoll() and
fork(). See http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for why this is needed (This used to be commit 6d06132ea9c5a1c7d098ba13f4146dc60e811e44)
-rw-r--r--source4/lib/events/events_standard.c42
1 files changed, 41 insertions, 1 deletions
diff --git a/source4/lib/events/events_standard.c b/source4/lib/events/events_standard.c
index 799b19813a..bae4d69688 100644
--- a/source4/lib/events/events_standard.c
+++ b/source4/lib/events/events_standard.c
@@ -58,6 +58,9 @@ struct std_event_context {
/* when using epoll this is the handle from epoll_create */
int epoll_fd;
+
+ /* our pid at the time the epoll_fd was created */
+ pid_t pid;
};
/* use epoll if it is available */
@@ -68,7 +71,9 @@ struct std_event_context {
*/
static void epoll_fallback_to_select(struct std_event_context *std_ev, const char *reason)
{
+ const char *cmd = talloc_asprintf(std_ev, "xterm -e gdb --pid %u", getpid());
DEBUG(0,("%s (%s) - falling back to select()\n", reason, strerror(errno)));
+ system(cmd);
close(std_ev->epoll_fd);
std_ev->epoll_fd = -1;
talloc_set_destructor(std_ev, NULL);
@@ -90,7 +95,9 @@ static uint32_t epoll_map_flags(uint16_t flags)
*/
static int epoll_ctx_destructor(struct std_event_context *std_ev)
{
- close(std_ev->epoll_fd);
+ if (std_ev->epoll_fd != -1) {
+ close(std_ev->epoll_fd);
+ }
std_ev->epoll_fd = -1;
return 0;
}
@@ -101,9 +108,32 @@ static int epoll_ctx_destructor(struct std_event_context *std_ev)
static void epoll_init_ctx(struct std_event_context *std_ev)
{
std_ev->epoll_fd = epoll_create(64);
+ std_ev->pid = getpid();
talloc_set_destructor(std_ev, epoll_ctx_destructor);
}
+static void epoll_add_event(struct std_event_context *std_ev, struct fd_event *fde);
+
+/*
+ reopen the epoll handle when our pid changes
+ see http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for an
+ demonstration of why this is needed
+ */
+static void epoll_reopen(struct std_event_context *std_ev)
+{
+ struct fd_event *fde;
+
+ close(std_ev->epoll_fd);
+ std_ev->epoll_fd = epoll_create(64);
+ if (std_ev->epoll_fd == -1) {
+ return;
+ }
+ std_ev->pid = getpid();
+ for (fde=std_ev->fd_events;fde;fde=fde->next) {
+ epoll_add_event(std_ev, fde);
+ }
+}
+
#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)
@@ -116,6 +146,16 @@ static void epoll_add_event(struct std_event_context *std_ev, struct fd_event *f
struct epoll_event event;
if (std_ev->epoll_fd == -1) return;
+ /* during an add event we need to check if our pid has changed
+ and re-open the epoll socket. Note that we don't need to do this
+ for other epoll changes */
+ if (std_ev->pid != getpid()) {
+ epoll_reopen(std_ev);
+ /* the current event gets added in epoll_reopen(), so
+ we can return here */
+ return;
+ }
+
fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
/* if we don't want events yet, don't add an epoll_event */