From ed1b58d8b53519e10a35c6a2bb49cac35f439621 Mon Sep 17 00:00:00 2001 From: Bodo Stroesser Date: Sat, 3 Sep 2005 15:57:24 -0700 Subject: [PATCH] [PATCH] uml: fix SIGWINCH handler race while waiting for signals. If a SIGWINCH comes in, while winch_thread() isn't waiting in wait(), winch_thread could miss signals. It isn't very probable, that anyone will see this causing trouble, as it would need a very special timing, that a missed SIGWINCH results in a wrong window size. So, this is a minor problem. But why not fix, as it can be done so easy? Signed-off-by: Bodo Stroesser Signed-off-by: Paolo 'Blaisorblade' Giarrusso Cc: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/drivers/chan_user.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/arch/um/drivers/chan_user.c b/arch/um/drivers/chan_user.c index 5d3768156c92..de3bce71aeb3 100644 --- a/arch/um/drivers/chan_user.c +++ b/arch/um/drivers/chan_user.c @@ -63,7 +63,7 @@ error: * * SIGWINCH can't be received synchronously, so you have to set up to receive it * as a signal. That being the case, if you are going to wait for it, it is - * convenient to sit in a pause() and wait for the signal to bounce you out of + * convenient to sit in sigsuspend() and wait for the signal to bounce you out of * it (see below for how we make sure to exit only on SIGWINCH). */ @@ -94,18 +94,19 @@ static int winch_thread(void *arg) "byte, err = %d\n", -count); /* We are not using SIG_IGN on purpose, so don't fix it as I thought to - * do! If using SIG_IGN, the pause() call below would not stop on + * do! If using SIG_IGN, the sigsuspend() call below would not stop on * SIGWINCH. */ signal(SIGWINCH, winch_handler); sigfillset(&sigs); - sigdelset(&sigs, SIGWINCH); - /* Block anything else than SIGWINCH. */ + /* Block all signals possible. */ if(sigprocmask(SIG_SETMASK, &sigs, NULL) < 0){ printk("winch_thread : sigprocmask failed, errno = %d\n", errno); exit(1); } + /* In sigsuspend(), block anything else than SIGWINCH. */ + sigdelset(&sigs, SIGWINCH); if(setsid() < 0){ printk("winch_thread : setsid failed, errno = %d\n", errno); @@ -130,7 +131,7 @@ static int winch_thread(void *arg) while(1){ /* This will be interrupted by SIGWINCH only, since other signals * are blocked.*/ - pause(); + sigsuspend(&sigs); count = os_write_file(pipe_fd, &c, sizeof(c)); if(count != sizeof(c)) -- 2.20.1