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r22959: cope with a rather interesting interaction between epoll() and

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fork(). See
http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for why
this is needed
This commit is contained in:
Andrew Tridgell 2007-05-17 02:18:29 +00:00 committed by Gerald (Jerry) Carter
parent c17df8bed6
commit 6d06132ea9
1 changed files with 41 additions and 1 deletions
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42
source/lib/events/events_standard.c
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@ -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 */