Re: [Qemu-devel] [PATCH 5/9] Monitor: Return before exiting with 'quit'

[Luiz Capitulino <lcapitulino@redhat.com>]

On Mon, 26 Apr 2010 13:25:38 -0500
Anthony Liguori <anthony@codemonkey.ws> wrote:

> On 04/26/2010 01:22 PM, Luiz Capitulino wrote:
> > On Mon, 26 Apr 2010 12:49:40 -0500
> > Anthony Liguori<anthony@codemonkey.ws>  wrote:
> >
> >    
> >> On 04/26/2010 10:47 AM, Luiz Capitulino wrote:
> >>      
> >>> The 'quit' Monitor command (implemented by do_quit()) calls
> >>> exit() directly, this is problematic under QMP because QEMU
> >>> exits before having a chance to send the ok response.
> >>>
> >>> Clients don't know if QEMU exited because of a problem or
> >>> because the 'quit' command has been executed.
> >>>
> >>> This commit fixes that by moving the exit() call to the main
> >>> loop, so that do_quit() requests the system to quit, instead
> >>> of calling exit() directly.
> >>>
> >>>        
> >> Does this also have the effect of printing out a (qemu) prompt after
> >> quit before an EOF appears on that socket?
> >>      
> >   Ah, right..
> >    
> 
> It's not necessarily a bad thing if it does.  I just wanted to raise 
> that because it's possible that someone depends on the behavior.

 Yes, and it's also a bit ugly if you do '-monitor stdio':

~/stuff/virt/ ./qemu-qmp -monitor stdio
QEMU 0.12.50 monitor - type 'help' for more information
(qemu) quit
(qemu) ~/stuff/virt/

 So, I'd like to fix it.

> I'm not sure it matters to me if we change this behavior though.

 It's very easy to fix, the following patch does it.

 I have (tested and) rebased the for-anthony branch with it.

From 14ecef47d1989f9b646fc0fe7a4bf42c091d1432 Mon Sep 17 00:00:00 2001
From: Luiz Capitulino <lcapitulino@redhat.com>
Date: Tue, 6 Apr 2010 18:55:54 -0300
Subject: [PATCH 5/9] Monitor: Return before exiting with 'quit'

The 'quit' Monitor command (implemented by do_quit()) calls
exit() directly, this is problematic under QMP because QEMU
exits before having a chance to send the ok response.

Clients don't know if QEMU exited because of a problem or
because the 'quit' command has been executed.

This commit fixes that by moving the exit() call to the main
loop, so that do_quit() requests the system to quit, instead
of calling exit() directly.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 monitor.c |    7 ++++++-
 sysemu.h  |    2 ++
 vl.c      |   18 ++++++++++++++++++
 3 files changed, 26 insertions(+), 1 deletions(-)

diff --git a/monitor.c b/monitor.c
index ef84298..5b0258f 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1017,7 +1017,12 @@ static void do_info_cpu_stats(Monitor *mon)
  */
 static int do_quit(Monitor *mon, const QDict *qdict, QObject **ret_data)
 {
-    exit(0);
+    if (monitor_ctrl_mode(mon)) {
+        qemu_system_exit_request();
+    } else {
+        exit(0);
+    }
+
     return 0;
 }
 
diff --git a/sysemu.h b/sysemu.h
index d0effa0..fa921df 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -45,9 +45,11 @@ void cpu_disable_ticks(void);
 void qemu_system_reset_request(void);
 void qemu_system_shutdown_request(void);
 void qemu_system_powerdown_request(void);
+void qemu_system_exit_request(void);
 int qemu_shutdown_requested(void);
 int qemu_reset_requested(void);
 int qemu_powerdown_requested(void);
+int qemu_exit_requested(void);
 extern qemu_irq qemu_system_powerdown;
 void qemu_system_reset(void);
 
diff --git a/vl.c b/vl.c
index a5a0f41..9ef6f2c 100644
--- a/vl.c
+++ b/vl.c
@@ -1697,6 +1697,7 @@ static int shutdown_requested;
 static int powerdown_requested;
 int debug_requested;
 int vmstop_requested;
+static int exit_requested;
 
 int qemu_shutdown_requested(void)
 {
@@ -1719,6 +1720,12 @@ int qemu_powerdown_requested(void)
     return r;
 }
 
+int qemu_exit_requested(void)
+{
+    /* just return it, we'll exit() anyway */
+    return exit_requested;
+}
+
 static int qemu_debug_requested(void)
 {
     int r = debug_requested;
@@ -1789,6 +1796,12 @@ void qemu_system_powerdown_request(void)
     qemu_notify_event();
 }
 
+void qemu_system_exit_request(void)
+{
+    exit_requested = 1;
+    qemu_notify_event();
+}
+
 #ifdef _WIN32
 static void host_main_loop_wait(int *timeout)
 {
@@ -1925,6 +1938,8 @@ static int vm_can_run(void)
         return 0;
     if (debug_requested)
         return 0;
+    if (exit_requested)
+        return 0;
     return 1;
 }
 
@@ -1977,6 +1992,9 @@ static void main_loop(void)
         if ((r = qemu_vmstop_requested())) {
             vm_stop(r);
         }
+        if (qemu_exit_requested()) {
+            exit(0);
+        }
     }
     pause_all_vcpus();
 }
-- 
1.7.1.rc1.12.ga6018