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[Qemu-devel] [PATCH v2] disable sigcld handling before calling pclose()
From: |
Wen Congyang |
Subject: |
[Qemu-devel] [PATCH v2] disable sigcld handling before calling pclose() |
Date: |
Tue, 21 Dec 2010 12:05:41 +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().
v2:
- Add stub functions for Win32
Signed-off-by: Wen Congyang <address@hidden>
---
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;
}
--
1.7.1