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Re: [Qemu-devel] [PATCH] Fix NULL alarm_timer pointer at exit
From: |
Marcelo Tosatti |
Subject: |
Re: [Qemu-devel] [PATCH] Fix NULL alarm_timer pointer at exit |
Date: |
Wed, 20 May 2009 16:08:35 -0300 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
Hi,
I think the right fix is to block SIGALRM in quit_timers, which
is called from main():
static void quit_timers(void)
{
alarm_timer->stop(alarm_timer);
alarm_timer = NULL;
}
On Sun, May 17, 2009 at 06:38:39PM +0200, Jean-Christophe Dubois wrote:
> This fixes a SIGSEGV error on qemu exit.
>
> Here is the valgrind output related to this error
>
> ==3648== Process terminating with default action of signal 11 (SIGSEGV)
>
> ==3648== Access not within mapped region at address 0x8
>
> ==3648== at 0x40636B: host_alarm_handler (vl.c:1345)
>
> ==3648== by 0x52D807F: (within /lib/libpthread-2.9.so)
>
> ==3648== by 0x5C0A12E: tcsetattr (in /lib/libc-2.9.so)
>
> ==3648== by 0x4DD601: term_exit (qemu-char.c:700)
>
> ==3648== by 0x5B636EC: exit (in /lib/libc-2.9.so)
>
> ==3648== by 0x5B4B5AC: (below main) (in /lib/libc-2.9.so)
>
> This simple fix check for a valid pointer as host_alarm_handler is
> also called after alarm_timer is released in the exit path.
>
> Signed-off-by: Jean-Christophe DUBOIS <address@hidden>
>
> --- qemu.org/vl.c 2009-05-16 17:57:27.000000000 +0200
> +++ qemu/vl.c 2009-05-17 17:15:29.000000000 +0200
> @@ -915,7 +915,7 @@
>
> static inline int alarm_has_dynticks(struct qemu_alarm_timer *t)
> {
> - return t->flags & ALARM_FLAG_DYNTICKS;
> + return t && (t->flags & ALARM_FLAG_DYNTICKS);
> }
>
> static void qemu_rearm_alarm_timer(struct qemu_alarm_timer *t)
> @@ -1349,7 +1349,7 @@
> qemu_timer_expired(active_timers[QEMU_TIMER_REALTIME],
> qemu_get_clock(rt_clock))) {
> qemu_event_increment();
> - alarm_timer->flags |= ALARM_FLAG_EXPIRED;
> + if (alarm_timer) alarm_timer->flags |= ALARM_FLAG_EXPIRED;
>
> #ifndef CONFIG_IOTHREAD
> if (next_cpu) {
>
>