At 12/21/2010 12:05 PM, Wen Congyang Write:
> When I use the command 'virsh save' to save the domain state,
> I receive the following error message:
> operation failed: Migration unexpectedly failed.
>
> I debug the qemu by adding some printf(), and find the function
> pclose() returns -1.
>
> I use strace to trace qemu, the log is as the following:
> ======
> close(17) = 0
> --- SIGCHLD (Child exited) @ 0 (0) ---
> wait4(-1, NULL, WNOHANG, NULL) = 22016
> rt_sigreturn(0) = 0
> wait4(22016, 0x7fff7f1034fc, 0, NULL) = -1 ECHILD (No child processes)
> ======
>
> We wait the child twice: one is in signal SIGCHLD handling and the other
> one is in pclose().
>
> We should disable sigcld handling before calling pclose().
>
> v2:
> - Add stub functions for Win32
>
> Signed-off-by: Wen Congyang <we...@cn.fujitsu.com>
>
> ---
> os-posix.c | 19 +++++++++++++++++++
> qemu-os-posix.h | 2 ++
> qemu-os-win32.h | 2 ++
> savevm.c | 2 ++
> 4 files changed, 25 insertions(+), 0 deletions(-)
>
> diff --git a/os-posix.c b/os-posix.c
> index 38c29d1..b163995 100644
> --- a/os-posix.c
> +++ b/os-posix.c
> @@ -86,6 +86,25 @@ void os_setup_signal_handling(void)
> sigaction(SIGCHLD, &act, NULL);
> }
>
> +void os_stop_sigchld_handling(void)
> +{
> + struct sigaction act;
> +
> + memset(&act, 0, sizeof(act));
> + act.sa_handler = SIG_DFL;
> + sigaction(SIGCHLD, &act, NULL);
> +}
> +
> +void os_resume_sigchld_handling(void)
> +{
> + struct sigaction act;
> +
> + memset(&act, 0, sizeof(act));
> + act.sa_handler = sigchld_handler;
> + act.sa_flags = SA_NOCLDSTOP;
> + sigaction(SIGCHLD, &act, NULL);
> +}
> +
> /* Find a likely location for support files using the location of the binary.
> For installed binaries this will be "$bindir/../share/qemu". When
> running from the build tree this will be "$bindir/../pc-bios". */
> diff --git a/qemu-os-posix.h b/qemu-os-posix.h
> index 81fd9ab..1c317f1 100644
> --- a/qemu-os-posix.h
> +++ b/qemu-os-posix.h
> @@ -33,6 +33,8 @@ static inline void os_host_main_loop_wait(int *timeout)
> void os_set_line_buffering(void);
> void os_set_proc_name(const char *s);
> void os_setup_signal_handling(void);
> +void os_stop_sigchld_handling(void);
> +void os_resume_sigchld_handling(void);
> void os_daemonize(void);
> void os_setup_post(void);
>
> diff --git a/qemu-os-win32.h b/qemu-os-win32.h
> index 1a07e5e..f31c5ef 100644
> --- a/qemu-os-win32.h
> +++ b/qemu-os-win32.h
> @@ -43,6 +43,8 @@ void qemu_del_wait_object(HANDLE handle, WaitObjectFunc
> *func, void *opaque);
> void os_host_main_loop_wait(int *timeout);
>
> static inline void os_setup_signal_handling(void) {}
> +static inline void os_stop_sigchld_handling(void) {}
> +static inline void os_resume_sigchld_handling(void) {}
> static inline void os_daemonize(void) {}
> static inline void os_setup_post(void) {}
> void os_set_line_buffering(void);
> diff --git a/savevm.c b/savevm.c
> index 90aa237..387b70b 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -234,7 +234,9 @@ static int stdio_pclose(void *opaque)
> {
> QEMUFileStdio *s = opaque;
> int ret;
> + os_stop_sigchld_handling();
> ret = pclose(s->stdio_file);
> + os_resume_sigchld_handling();
> qemu_free(s);
> return ret;
> }
Ping Again... :)
This is a bug fix.
2 months has gone, but I do not receive any comment.
Should we remove SIGCHLD handling as Paolo said?
