unix: fix signal handling data race

src/unix/core.c

@@ -22,6 +22,7 @@
 #include "internal.h"
 #include "strtok.h"
 
+#include <stdatomic.h>
 #include <stddef.h> /* NULL */
 #include <stdio.h> /* printf */
 #include <stdlib.h>
@@ -289,6 +290,7 @@ int uv__getiovmax(void) {
 
 
 static void uv__finish_close(uv_handle_t* handle) {
+ atomic_uint caught_signals;
  uv_signal_t* sh;
 
  /* Note: while the handle is in the UV_HANDLE_CLOSING state now, it's still
@@ -322,7 +324,9 @@ static void uv__finish_close(uv_handle_t* handle) {
  * okay because we only need to deliver the pending events.
  */
  sh = (uv_signal_t*) handle;
- if (sh->caught_signals > sh->dispatched_signals) {
+ caught_signals = atomic_load_explicit((atomic_uint*) &sh->caught_signals,
+ memory_order_seq_cst);
+ if (caught_signals > sh->dispatched_signals) {
  handle->flags ^= UV_HANDLE_CLOSED;
  uv__make_close_pending(handle); /* Back into the queue. */
  return;

src/unix/signal.c

@@ -24,6 +24,7 @@
 #include <assert.h>
 #include <errno.h>
 #include <signal.h>
+#include <stdatomic.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
@@ -231,8 +232,10 @@ static void uv__signal_handler(int signum) {
  assert(r == sizeof msg ||
  (r == -1 && (errno == EAGAIN || errno == EWOULDBLOCK)));
 
- if (r != -1)
- handle->caught_signals++;
+ if (r != -1) {
+ atomic_fetch_add_explicit((atomic_uint*) &handle->caught_signals, 1,
+ memory_order_seq_cst);
+ }
  }
 
  uv__signal_unlock();