From 94ab7455abc213fc96760e29ab2e943ec682fb22 Mon Sep 17 00:00:00 2001 From: Daniel Drake Date: Tue, 12 May 2015 16:39:22 -0600 Subject: [PATCH] Allow system call restarts upon signal interruption The X server frequently deals with SIGIO and SIGALRM interruptions. If process execution is inside certain blocking system calls when these signals arrive, e.g. with the kernel blocked on a contended semaphore, the system calls will be interrupted. Some system calls are automatically restartable (the kernel re-executes them with the same parameters once the signal handler returns) but only if the signal handler allows it. Set SA_RESTART on the signal handlers to enable this convenient behaviour. Reviewed-by: Adam Jackson Signed-off-by: Daniel Drake --- hw/xfree86/os-support/shared/sigio.c | 2 +- os/utils.c | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/hw/xfree86/os-support/shared/sigio.c b/hw/xfree86/os-support/shared/sigio.c index 45949f7a3..c746d02fc 100644 --- a/hw/xfree86/os-support/shared/sigio.c +++ b/hw/xfree86/os-support/shared/sigio.c @@ -178,7 +178,7 @@ xf86InstallSIGIOHandler(int fd, void (*f) (int, void *), void *closure) } sigemptyset(&sa.sa_mask); sigaddset(&sa.sa_mask, SIGIO); - sa.sa_flags = 0; + sa.sa_flags = SA_RESTART; sa.sa_handler = xf86SIGIO; sigaction(SIGIO, &sa, &osa); xf86SigIOFuncs[i].fd = fd; diff --git a/os/utils.c b/os/utils.c index 868eb043a..9b6fb3081 100644 --- a/os/utils.c +++ b/os/utils.c @@ -1255,6 +1255,7 @@ SmartScheduleInit(void) memset((char *) &act, 0, sizeof(struct sigaction)); /* Set up the timer signal function */ + act.sa_flags = SA_RESTART; act.sa_handler = SmartScheduleTimer; sigemptyset(&act.sa_mask); sigaddset(&act.sa_mask, SIGALRM);