From 73f7d5048c0e2ad4817ad208de02adee73938ed0 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Sat, 31 May 2014 06:05:29 +0200
Subject: Unblock signals only during poll/epoll wait

If signals are normally blocked, we can avoid a lot of EINTR handling.
---
 src/fastd.c | 10 ++++------
 src/poll.c  | 16 ++++++++++++++++
 src/shell.c | 25 +++----------------------
 3 files changed, 23 insertions(+), 28 deletions(-)

diff --git a/src/fastd.c b/src/fastd.c
index fc98ef5..c129a3c 100644
--- a/src/fastd.c
+++ b/src/fastd.c
@@ -96,6 +96,10 @@ static void on_sigchld(int signo UNUSED) {
 static void init_signals(void) {
 	struct sigaction action;
 
+	sigset_t set, oldset;
+	sigfillset(&set);
+	pthread_sigmask(SIG_SETMASK, &set, &oldset);
+
 	action.sa_flags = 0;
 	sigemptyset(&action.sa_mask);
 
@@ -629,10 +633,6 @@ static inline void reap_zombies(void) {
 
 /** The \em real signal handlers */
 static inline void handle_signals(void) {
-	sigset_t set, oldset;
-	sigfillset(&set);
-	pthread_sigmask(SIG_SETMASK, &set, &oldset);
-
 	if (sighup) {
 		sighup = false;
 
@@ -651,8 +651,6 @@ static inline void handle_signals(void) {
 		sigchld = false;
 		reap_zombies();
 	}
-
-	pthread_sigmask(SIG_SETMASK, &oldset, NULL);
 }
 
 
diff --git a/src/poll.c b/src/poll.c
index a2d206b..f05a345 100644
--- a/src/poll.c
+++ b/src/poll.c
@@ -34,6 +34,10 @@
 #include "async.h"
 #include "peer.h"
 
+#include <pthread.h>
+#include <signal.h>
+
+
 #ifdef USE_EPOLL
 
 #include <sys/epoll.h>
@@ -129,6 +133,10 @@ void fastd_poll_handle(void) {
 	if (timeout < 0 || timeout > maintenance_timeout)
 		timeout = maintenance_timeout;
 
+	sigset_t set, oldset;
+	sigemptyset(&set);
+	pthread_sigmask(SIG_SETMASK, &set, &oldset);
+
 	struct epoll_event events[16];
 	int ret = epoll_wait(ctx.epoll_fd, events, 16, timeout);
 	if (ret < 0) {
@@ -138,6 +146,8 @@ void fastd_poll_handle(void) {
 		exit_errno("epoll_wait");
 	}
 
+	pthread_sigmask(SIG_SETMASK, &oldset, NULL);
+
 	fastd_update_time();
 
 	size_t i;
@@ -243,6 +253,10 @@ void fastd_poll_handle(void) {
 	if (VECTOR_LEN(ctx.pollfds) != 2 + ctx.n_socks + VECTOR_LEN(ctx.peers))
 		exit_bug("fd count mismatch");
 
+	sigset_t set, oldset;
+	sigemptyset(&set);
+	pthread_sigmask(SIG_SETMASK, &set, &oldset);
+
 	int ret = poll(VECTOR_DATA(ctx.pollfds), VECTOR_LEN(ctx.pollfds), timeout);
 	if (ret < 0) {
 		if (errno == EINTR)
@@ -251,6 +265,8 @@ void fastd_poll_handle(void) {
 		exit_errno("poll");
 	}
 
+	pthread_sigmask(SIG_SETMASK, &oldset, NULL);
+
 	fastd_update_time();
 
 	if (VECTOR_INDEX(ctx.pollfds, 0).revents & POLLIN)
diff --git a/src/shell.c b/src/shell.c
index c161a9e..076c4c8 100644
--- a/src/shell.c
+++ b/src/shell.c
@@ -138,11 +138,10 @@ static bool shell_command_do_exec(const fastd_shell_command_t *command, const fa
 
 	shell_command_setenv(parent, env);
 
-	/* unblock SIGCHLD */
+	/* unblock signals */
 	sigset_t set;
 	sigemptyset(&set);
-	sigaddset(&set, SIGCHLD);
-	pthread_sigmask(SIG_UNBLOCK, &set, NULL);
+	pthread_sigmask(SIG_SETMASK, &set, NULL);
 
 	execl("/bin/sh", "sh", "-c", command->command, (char*)NULL);
 	_exit(127);
@@ -157,23 +156,13 @@ bool fastd_shell_command_exec_sync(const fastd_shell_command_t *command, const f
 	if (!fastd_shell_command_isset(command))
 		return true;
 
-	/* block SIGCHLD */
-	sigset_t set, oldset;
-	sigemptyset(&set);
-	sigaddset(&set, SIGCHLD);
-	pthread_sigmask(SIG_BLOCK, &set, &oldset);
-
 	pid_t pid;
-	if (!shell_command_do_exec(command, env, &pid)) {
-		pthread_sigmask(SIG_SETMASK, &oldset, NULL);
+	if (!shell_command_do_exec(command, env, &pid))
 		return false;
-	}
 
 	int status;
 	pid_t err = waitpid(pid, &status, 0);
 
-	pthread_sigmask(SIG_SETMASK, &oldset, NULL);
-
 	if (err <= 0) {
 		pr_error_errno("fastd_shell_command_exec_sync: waitpid");
 		return false;
@@ -199,17 +188,9 @@ bool fastd_shell_command_exec_sync(const fastd_shell_command_t *command, const f
    on SIGCHLD.
 */
 static void shell_command_exec_async(const fastd_shell_command_t *command, const fastd_shell_env_t *env) {
-	/* block SIGCHLD */
-	sigset_t set, oldset;
-	sigemptyset(&set);
-	sigaddset(&set, SIGCHLD);
-	pthread_sigmask(SIG_BLOCK, &set, &oldset);
-
 	pid_t pid;
 	if (shell_command_do_exec(command, env, &pid))
 		VECTOR_ADD(ctx.async_pids, pid);
-
-	pthread_sigmask(SIG_SETMASK, &oldset, NULL);
 }
 
 /** Executes a shell command */
-- 
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