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Re: [Qemu-devel] [PATCH qemu-ga] Fix a bug where qemu-ga service is stuc


From: Michael Roth
Subject: Re: [Qemu-devel] [PATCH qemu-ga] Fix a bug where qemu-ga service is stuck during stop operation
Date: Tue, 04 Apr 2017 18:52:37 -0500
User-agent: alot/0.5.1

Quoting Sameeh Jubran (2017-03-21 08:59:11)
> After triggering a freeze command without any following thaw command,
> qemu-ga will not respond to stop operation. This behaviour is wanted on Linux
> as there is no time limit for a freeze command and we want to prevent
> quitting in the middle of freeze, on the other hand on Windows the time
> limit for freeze is 10 seconds, so we should wait for the timeout, thaw
> the file system and quit.
> 
> Signed-off-by: Sameeh Jubran <address@hidden>
> ---
>  qga/main.c                 | 20 ++++++++++++++++++++
>  qga/vss-win32.h            |  1 +
>  qga/vss-win32/vss-common.h |  5 +++++
>  3 files changed, 26 insertions(+)
> 
> diff --git a/qga/main.c b/qga/main.c
> index 92658bc..de37c85 100644
> --- a/qga/main.c
> +++ b/qga/main.c
> @@ -130,9 +130,29 @@ static void quit_handler(int sig)
>       * unless all log/pid files are on unfreezable filesystems. there's
>       * also a very likely chance killing the agent before unfreezing
>       * the filesystems is a mistake (or will be viewed as one later).
> +     * On Windows the freeze interval is limited to 10 seconds, so
> +     * we should quit, but first we should wait for the timeout, thaw
> +     * the filesystem and quit.
>       */
>      if (ga_is_frozen(ga_state)) {
> +#ifdef _WIN32
> +        int i = 0;
> +        Error *err = NULL;
> +        HANDLE hEventTimeout;

Maybe add the following to help explain the added delay:

           g_debug("Thawing filesystems before exiting");

> +
> +        hEventTimeout = OpenEvent(EVENT_ALL_ACCESS, FALSE, 
> EVENT_NAME_TIMEOUT);
> +        if (hEventTimeout) {
> +            WaitForSingleObject(hEventTimeout, 0);
> +            CloseHandle(hEventTimeout);
> +        }
> +        qga_vss_fsfreeze(&i, &err, false);
> +        if (err) {
> +            g_debug("Error: %s", error_get_pretty(err));

Perhaps: "Error unfreezing filesystems prior to exiting: %s"

> +            error_free(err);
> +        }
> +#else
>          return;
> +#endif
>      }
>      g_debug("received signal num %d, quitting", sig);
> 
> diff --git a/qga/vss-win32.h b/qga/vss-win32.h
> index 4d1d150..5f4ea70 100644
> --- a/qga/vss-win32.h
> +++ b/qga/vss-win32.h
> @@ -13,6 +13,7 @@
>  #ifndef VSS_WIN32_H
>  #define VSS_WIN32_H
> 
> +#include "qga/vss-win32/vss-common.h"
> 
>  bool vss_init(bool init_requester);
>  void vss_deinit(bool deinit_requester);
> diff --git a/qga/vss-win32/vss-common.h b/qga/vss-win32/vss-common.h
> index c81a856..5756d00 100644
> --- a/qga/vss-win32/vss-common.h
> +++ b/qga/vss-win32/vss-common.h
> @@ -12,6 +12,7 @@
> 
>  #ifndef VSS_COMMON_H
>  #define VSS_COMMON_H
> +#ifndef VSS_WIN32_H
> 
>  #define __MIDL_user_allocate_free_DEFINED__
>  #include <windows.h>
> @@ -57,6 +58,7 @@
>  #define L(a) _L(a)
> 
>  /* Constants for QGA VSS Provider */
> +#endif
> 
>  #define QGA_PROVIDER_NAME "QEMU Guest Agent VSS Provider"
>  #define QGA_PROVIDER_LNAME L(QGA_PROVIDER_NAME)
> @@ -66,6 +68,8 @@
>  #define EVENT_NAME_THAW    "Global\\QGAVSSEvent-thaw"
>  #define EVENT_NAME_TIMEOUT "Global\\QGAVSSEvent-timeout"

This is a bit of tangle. I'd rather you just move these out
into a separate header, vss-handles.h or something, and then
include that in main.c and vss-common.h.

> 
> +#ifndef VSS_WIN32_H
> +
>  const GUID g_gProviderId = { 0x3629d4ed, 0xee09, 0x4e0e,
>      {0x9a, 0x5c, 0x6d, 0x8b, 0xa2, 0x87, 0x2a, 0xef} };
>  const GUID g_gProviderVersion = { 0x11ef8b15, 0xcac6, 0x40d6,
> @@ -126,3 +130,4 @@ public:
>  };
> 
>  #endif
> +#endif
> -- 
> 2.9.3
> 




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