Fix a race condition when do_sigchld, uloop_cancelled were set just
before epoll_wait(timeout=-1), resulting the loop stuck in the syscall
without noticing the events just happened
Signed-off-by: Yousong Zhou <yszhou4t...@gmail.com>
---
uloop-epoll.c | 2 +-
uloop-kqueue.c | 2 +-
uloop.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++----
3 files changed, 63 insertions(+), 6 deletions(-)
diff --git a/uloop-epoll.c b/uloop-epoll.c
index bb652fd..6014bea 100644
--- a/uloop-epoll.c
+++ b/uloop-epoll.c
@@ -23,7 +23,7 @@
#define EPOLLRDHUP 0x2000
#endif
-int uloop_init(void)
+static int uloop_init_pollfd(void)
{
if (poll_fd >= 0)
return 0;
diff --git a/uloop-kqueue.c b/uloop-kqueue.c
index 0cb1c14..ba5595b 100644
--- a/uloop-kqueue.c
+++ b/uloop-kqueue.c
@@ -15,7 +15,7 @@
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
-int uloop_init(void)
+static int uloop_init_pollfd(void)
{
struct timespec timeout = { 0, 0 };
struct kevent ev = {};
diff --git a/uloop.c b/uloop.c
index cd3de85..b59c31f 100644
--- a/uloop.c
+++ b/uloop.c
@@ -63,6 +63,11 @@ static bool do_sigchld = false;
static struct uloop_fd_event cur_fds[ULOOP_MAX_EVENTS];
static int cur_fd, cur_nfds;
+static int waker_pipe[2] = {-1, -1};
+static struct uloop_fd waker_fd;
+
+int uloop_fd_add(struct uloop_fd *sock, unsigned int flags);
+
#ifdef USE_KQUEUE
#include "uloop-kqueue.c"
#endif
@@ -71,6 +76,45 @@ static int cur_fd, cur_nfds;
#include "uloop-epoll.c"
#endif
+static void waker_consume(struct uloop_fd *fd, unsigned int events)
+{
+ char buf[4];
+
+ while (read(fd->fd, buf, 4) > 0)
+ ;
+}
+
+static int waker_init(void)
+{
+ if (waker_pipe[0] >= 0 && waker_pipe[1] >= 0)
+ return 0;
+
+ if (pipe(waker_pipe) < 0)
+ return -1;
+
+ fcntl(waker_pipe[0], F_SETFD, fcntl(waker_pipe[0], F_GETFD) |
O_NONBLOCK);
+ fcntl(waker_pipe[1], F_SETFD, fcntl(waker_pipe[1], F_GETFD) |
O_NONBLOCK);
+
+ waker_fd.fd = waker_pipe[0];
+ waker_fd.cb = waker_consume;
+ uloop_fd_add(&waker_fd, ULOOP_READ);
+
+ return 0;
+}
+
+int uloop_init(void)
+{
+ if (uloop_init_pollfd() < 0)
+ return -1;
+
+ if (waker_init() < 0) {
+ close(poll_fd);
+ poll_fd = -1;
+ return -1;
+ }
+ return 0;
+}
+
static bool uloop_fd_stack_event(struct uloop_fd *fd, int events)
{
struct uloop_fd_stack *cur;
@@ -330,12 +374,18 @@ static void uloop_handle_processes(void)
static void uloop_handle_sigint(int signo)
{
+ char buf[1] = {'w'};
+
uloop_cancelled = true;
+ write(waker_pipe[1], buf, 1);
}
static void uloop_sigchld(int signo)
{
+ char buf[1] = {'w'};
+
do_sigchld = true;
+ write(waker_pipe[1], buf, 1);
}
static void uloop_install_handler(int signum, void (*handler)(int), struct
sigaction* old, bool add)
@@ -477,11 +527,18 @@ void uloop_run(void)
void uloop_done(void)
{
- if (poll_fd < 0)
- return;
+ int i;
- close(poll_fd);
- poll_fd = -1;
+ if (poll_fd >= 0) {
+ close(poll_fd);
+ poll_fd = -1;
+ }
+ for (i = 0; i < ARRAY_SIZE(waker_pipe); i++) {
+ if (waker_pipe[i] >= 0) {
+ close(waker_pipe[i]);
+ waker_pipe[i] = -1;
+ }
+ }
uloop_clear_timeouts();
uloop_clear_processes();
--
2.6.4
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