On Thu, Jun 3, 2021 at 8:27 PM Ruediger Pluem <[email protected]> wrote:
>
> Looking at the stack trace, would we need to call apr_setup_signal_thread()
> (if we have APR_THREADS) before we run
> ap_run_child_init and unblock all signals afterwards in case one of the init
> child hooks creates threads like mod_watchdog does?
Agreed, what about the attached patch?
Regards;
Yann.
Index: server/mpm/prefork/prefork.c
===================================================================
--- server/mpm/prefork/prefork.c (revision 1890421)
+++ server/mpm/prefork/prefork.c (working copy)
@@ -376,11 +376,23 @@ static void stop_listening(int sig)
static int requests_this_child;
static int num_listensocks = 0;
+#if APR_HAS_THREADS
+static void child_sigmask(sigset_t *new_mask, sigset_t *old_mask)
+{
+#if defined(SIGPROCMASK_SETS_THREAD_MASK)
+ sigprocmask(SIG_SETMASK, new_mask, old_mask);
+#else
+ pthread_sigmask(SIG_SETMASK, new_mask, old_mask);
+#endif
+}
+#endif
+
static void child_main(int child_num_arg, int child_bucket)
{
#if APR_HAS_THREADS
apr_thread_t *thd = NULL;
apr_os_thread_t osthd;
+ sigset_t sig_mask;
#endif
apr_pool_t *ptrans;
apr_allocator_t *allocator;
@@ -446,8 +458,30 @@ static void child_main(int child_num_arg, int chil
clean_child_exit(APEXIT_CHILDFATAL);
}
+#if APR_HAS_THREADS
+ /* Save the signal mask and Use apr_setup_signal_thread to block all
+ * the signals from being received by threads potentially created by
+ * child_init() hooks.
+ */
+ child_sigmask(NULL, &sig_mask);
+ {
+ apr_status_t rv;
+ rv = apr_setup_signal_thread();
+ if (rv != APR_SUCCESS) {
+ ap_log_error(APLOG_MARK, APLOG_EMERG, rv, ap_server_conf, APLOGNO()
+ "Couldn't initialize signal thread");
+ clean_child_exit(APEXIT_CHILDFATAL);
+ }
+ }
+#endif /* APR_HAS_THREADS */
+
ap_run_child_init(pchild, ap_server_conf);
+#if APR_HAS_THREADS
+ /* Restore the original signal mask in the main child thread. */
+ child_sigmask(&sig_mask, NULL);
+#endif
+
ap_create_sb_handle(&sbh, pchild, my_child_num, 0);
(void) ap_update_child_status(sbh, SERVER_READY, (request_rec *) NULL);
