I didn't have the time to test the patch, but I guess, it won't work.
Maybe, the man pages for sigsuspend are somewhat missleading, saying:
The sigsuspend call temporarily replaces the signal mask for
the process with that given by mask and then suspends the
process until a signal is received.Reading the code of sys_sigsuspend() in arch/i386/kernel/signal.c, you'll find that it will return to user only, if do_signal() returns 1. This will happen, if there was a signal to deliver. Ignored signals will not be delivered, so sys_sigsupend will not return on SIGWINCH, if SIGWINCH handler is set to SIG_IGN.
So, for UML's winch_handler, there is no difference between pause() and sigsuspend(), because sigsuspend's feature of accepting a sigmask for use while waiting, in fact isn't needed here as the same mask is set already before with sigprocmask().
Bodo
[EMAIL PROTECTED] wrote:
Replace pause with sigsuspend, to avoid needing to set an empty handler for SIGWINCH.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <[EMAIL PROTECTED]> ---
linux-2.6.git-paolo/arch/um/drivers/chan_user.c | 15 ++++----------- 1 files changed, 4 insertions(+), 11 deletions(-)
diff -puN arch/um/drivers/chan_user.c~uml-replace-pause-with-sigsuspend arch/um/drivers/chan_user.c
--- linux-2.6.git/arch/um/drivers/chan_user.c~uml-replace-pause-with-sigsuspend 2005-05-16 08:07:30.000000000 +0200
+++ linux-2.6.git-paolo/arch/um/drivers/chan_user.c 2005-05-16 08:08:10.000000000 +0200
@@ -67,10 +67,6 @@ error:
* it (see below for how we make sure to exit only on SIGWINCH).
*/
-static void winch_handler(int sig)
-{
-}
-
struct winch_data {
int pty_fd;
int pipe_fd;
@@ -93,14 +89,11 @@ static int winch_thread(void *arg)
printk("winch_thread : failed to write synchronization "
"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
- * SIGWINCH. */
-
- signal(SIGWINCH, winch_handler);
sigfillset(&sigs);
sigdelset(&sigs, SIGWINCH);
- /* Block anything else than SIGWINCH. */
+ /* Block anything else than SIGWINCH. XXX: Actually, this may be removed
+ * maybe, due to sigsuspend below, which replaces the signal mask, but
+ * let's keep it.*/
if(sigprocmask(SIG_SETMASK, &sigs, NULL) < 0){
printk("winch_thread : sigprocmask failed, errno = %d\n", errno);
@@ -130,7 +123,7 @@ 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))
_
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