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[Qemu-devel] [PATCH] disable sigcld handling before calling pclose()
From: |
Wen Congyang |
Subject: |
[Qemu-devel] [PATCH] disable sigcld handling before calling pclose() |
Date: |
Thu, 09 Dec 2010 11:41:58 +0800 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100413 Fedora/3.0.4-2.fc13 Thunderbird/3.0.4 |
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().
Signed-off-by: Wen Congyang <address@hidden>
---
os-posix.c | 19 +++++++++++++++++++
qemu-os-posix.h | 2 ++
savevm.c | 2 ++
3 files changed, 23 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 353f878..e819295 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/savevm.c b/savevm.c
index d38f79e..08a5f88 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;
}
--
1.7.1
- [Qemu-devel] [PATCH] disable sigcld handling before calling pclose(),
Wen Congyang <=