[Xen-devel] [PATCH] tools: add closure to xc_domain_save switch_qemu_logdirty callback

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1286899422 -3600
# Node ID 92be1317280b14e63b381285cdf342dfae014e66
# Parent  372959917c012db7d90aad0626a4af6b8f9b186f
tools: add closure to xc_domain_save switch_qemu_logdirty callback

Also move the function into struct save_callbacks with the others.

Use this in libxl to pass the save context to
libxl__domain_suspend_common_switch_qemu_logdirty allowing us to reuse
the parent's xenstore handle, gc context etc.

Also add an apparently missing libxl__free_all to
libxl__domain_suspend_common.

(Now that switch_qemu_logdirty takes a closure it's not clear if
checkpoint can be changed to use the callback rather than doing the
switch itself and implementing a nop callback, Branden?)

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
Change from v1:
  Compile test from missed call to xc_domain_save in
  tools/python/xen/lowlevel/checkpoint/libcheckpoint.c

diff -r 372959917c01 -r 92be1317280b tools/libxc/xc_domain_save.c
--- a/tools/libxc/xc_domain_save.c      Tue Oct 12 17:03:42 2010 +0100
+++ b/tools/libxc/xc_domain_save.c      Tue Oct 12 17:03:42 2010 +0100
@@ -879,7 +879,7 @@ int xc_domain_save(xc_interface *xch, in
 int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t 
max_iters,
                    uint32_t max_factor, uint32_t flags,
                    struct save_callbacks* callbacks,
-                   int hvm, void (*switch_qemu_logdirty)(int, unsigned))
+                   int hvm)
 {
     xc_dominfo_t info;
     DECLARE_DOMCTL;
@@ -1015,7 +1015,7 @@ int xc_domain_save(xc_interface *xch, in
 
         /* Enable qemu-dm logging dirty pages to xen */
         if ( hvm )
-            switch_qemu_logdirty(dom, 1);
+            callbacks->switch_qemu_logdirty(dom, 1, callbacks->data);
     }
     else
     {
@@ -1876,7 +1876,7 @@ int xc_domain_save(xc_interface *xch, in
                                NULL, 0, NULL, 0, NULL) < 0 )
             DPRINTF("Warning - couldn't disable shadow mode");
         if ( hvm )
-            switch_qemu_logdirty(dom, 0);
+            callbacks->switch_qemu_logdirty(dom, 0, callbacks->data);
     }
 
     if ( live_shinfo )
diff -r 372959917c01 -r 92be1317280b tools/libxc/xenguest.h
--- a/tools/libxc/xenguest.h    Tue Oct 12 17:03:42 2010 +0100
+++ b/tools/libxc/xenguest.h    Tue Oct 12 17:03:42 2010 +0100
@@ -40,6 +40,8 @@ struct save_callbacks {
      * 1: take another checkpoint */
     int (*checkpoint)(void* data);
 
+    void (*switch_qemu_logdirty)(int domid, unsigned enable, void *data); /* 
HVM only */
+
     /* to be provided as the first argument to each callback function */
     void* data;
 };
@@ -55,7 +57,7 @@ int xc_domain_save(xc_interface *xch, in
 int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t 
max_iters,
                    uint32_t max_factor, uint32_t flags /* XCFLAGS_xxx */,
                    struct save_callbacks* callbacks,
-                   int hvm, void (*switch_qemu_logdirty)(int, unsigned)); /* 
HVM only */
+                   int hvm);
 
 
 /**
diff -r 372959917c01 -r 92be1317280b tools/libxl/libxl_dom.c
--- a/tools/libxl/libxl_dom.c   Tue Oct 12 17:03:42 2010 +0100
+++ b/tools/libxl/libxl_dom.c   Tue Oct 12 17:03:42 2010 +0100
@@ -325,21 +325,18 @@ struct suspendinfo {
     unsigned int flags;
 };
 
-static void libxl__domain_suspend_common_switch_qemu_logdirty(int domid, 
unsigned int enable)
+static void libxl__domain_suspend_common_switch_qemu_logdirty(int domid, 
unsigned int enable, void *data)
 {
-    struct xs_handle *xsh;
-    char path[64];
+    struct suspendinfo *si = data;
+    libxl_ctx *ctx = libxl__gc_owner(si->gc);
+    char *path;
 
-    snprintf(path, sizeof(path), 
"/local/domain/0/device-model/%u/logdirty/cmd", domid);
-
-    xsh = xs_daemon_open();
+    path = libxl__sprintf(si->gc, 
"/local/domain/0/device-model/%u/logdirty/cmd", domid);
 
     if (enable)
-        xs_write(xsh, XBT_NULL, path, "enable", strlen("enable"));
+        xs_write(ctx->xsh, XBT_NULL, path, "enable", strlen("enable"));
     else
-        xs_write(xsh, XBT_NULL, path, "disable", strlen("disable"));
-
-    xs_daemon_close(xsh);
+        xs_write(ctx->xsh, XBT_NULL, path, "disable", strlen("disable"));
 }
 
 static int libxl__domain_suspend_common_callback(void *data)
@@ -437,11 +434,11 @@ int libxl__domain_suspend_common(libxl_c
 
     memset(&callbacks, 0, sizeof(callbacks));
     callbacks.suspend = libxl__domain_suspend_common_callback;
+    callbacks.switch_qemu_logdirty = 
libxl__domain_suspend_common_switch_qemu_logdirty;
     callbacks.data = &si;
 
     xc_domain_save(ctx->xch, fd, domid, 0, 0, flags,
-                   &callbacks, hvm,
-                   &libxl__domain_suspend_common_switch_qemu_logdirty);
+                   &callbacks, hvm);
 
     if (si.suspend_eventchn > 0)
         xc_suspend_evtchn_release(ctx->xch, si.xce, domid, 
si.suspend_eventchn);
@@ -450,6 +447,7 @@ int libxl__domain_suspend_common(libxl_c
 
     rc = 0;
 out:
+    libxl__free_all(&gc);
     return rc;
 }
 
diff -r 372959917c01 -r 92be1317280b 
tools/python/xen/lowlevel/checkpoint/libcheckpoint.c
--- a/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c      Tue Oct 12 
17:03:42 2010 +0100
+++ b/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c      Tue Oct 12 
17:03:42 2010 +0100
@@ -164,7 +164,7 @@ void checkpoint_close(checkpoint_state* 
 
 /* we toggle logdirty ourselves around the xc_domain_save call --
  * it avoids having to pass around checkpoint_state */
-static void noop_switch_logdirty(int domid, unsigned enable)
+static void noop_switch_logdirty(int domid, unsigned enable, void *data)
 {
     return;
 }
@@ -189,8 +189,9 @@ int checkpoint_start(checkpoint_state* s
            return rc;
     }
 
-    rc = xc_domain_save(s->xch, fd, s->domid, 0, 0, flags, callbacks, hvm,
-       noop_switch_logdirty);
+    callbacks->switch_qemu_logdirty = noop_switch_logdirty;
+
+    rc = xc_domain_save(s->xch, fd, s->domid, 0, 0, flags, callbacks, hvm);
 
     if (hvm)
        switch_qemu_logdirty(s, 0);
diff -r 372959917c01 -r 92be1317280b tools/xcutils/xc_save.c
--- a/tools/xcutils/xc_save.c   Tue Oct 12 17:03:42 2010 +0100
+++ b/tools/xcutils/xc_save.c   Tue Oct 12 17:03:42 2010 +0100
@@ -102,7 +102,7 @@ static int suspend(void* data)
  * active buffer. */
 
 
-static void switch_qemu_logdirty(int domid, unsigned int enable)
+static void switch_qemu_logdirty(int domid, unsigned int enable, void *data)
 {
     struct xs_handle *xs;
     char *path, *p, *ret_str, *cmd_str, **watch;
@@ -205,9 +205,9 @@ main(int argc, char **argv)
     }
     memset(&callbacks, 0, sizeof(callbacks));
     callbacks.suspend = suspend;
+    callbacks.switch_qemu_logdirty = switch_qemu_logdirty;
     ret = xc_domain_save(si.xch, io_fd, si.domid, maxit, max_f, si.flags, 
-                         &callbacks, !!(si.flags & XCFLAGS_HVM),
-                         &switch_qemu_logdirty);
+                         &callbacks, !!(si.flags & XCFLAGS_HVM));
 
     if (si.suspend_evtchn > 0)
         xc_suspend_evtchn_release(si.xch, si.xce, si.domid, si.suspend_evtchn);

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