[Xen-devel] [PATCH 4 of 9 v2] libxl: introduce libxl__wait_for_device_state

[Roger Pau Monne <roger.pau@xxxxxxxxxxxxx>]

# HG changeset patch
# User Roger Pau Monne <roger.pau@xxxxxxxxxxxxx>
# Date 1321609740 -3600
# Node ID a77bba3717402fdf24a72d028ae0f3d482e6f427
# Parent  ec94a7e4983ad6338db20fa0777a85507b582607
libxl: introduce libxl__wait_for_device_state

This is a generic function, that waits for xs watches to reach a
certain state and then executes the passed helper function. Removed
wait_for_dev_destroy and used this new function instead. This
function will also be used by future patches that need to wait for
the initialization of devices before executing hotplug scripts.

Signed-off-by: Roger Pau Monne <roger.pau@xxxxxxxxxxxxx>

diff -r ec94a7e4983a -r a77bba371740 tools/libxl/libxl_device.c
--- a/tools/libxl/libxl_device.c        Fri Nov 18 10:46:54 2011 +0100
+++ b/tools/libxl/libxl_device.c        Fri Nov 18 10:49:00 2011 +0100
@@ -370,7 +370,9 @@ int libxl__device_disk_dev_number(const 
  * Returns 0 if a device is removed, ERROR_* if an error
  * or timeout occurred.
  */
-static int wait_for_dev_destroy(libxl__gc *gc, struct timeval *tv)
+int libxl__wait_for_device_state(libxl__gc *gc, struct timeval *tv,
+                                 int state,
+                                 libxl__device_state_handler handler)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
     int nfds, rc;
@@ -395,17 +397,14 @@ start:
         default:
             l1 = xs_read_watch(ctx->xsh, &n);
             if (l1 != NULL) {
-                char *state = libxl__xs_read(gc, XBT_NULL,
+                char *sstate = libxl__xs_read(gc, XBT_NULL,
                                              l1[XS_WATCH_PATH]);
-                if (!state || atoi(state) == 6) {
-                    xs_unwatch(ctx->xsh, l1[0], l1[1]);
-                    xs_rm(ctx->xsh, XBT_NULL, l1[XS_WATCH_TOKEN]);
-                    LIBXL__LOG(ctx, LIBXL__LOG_DEBUG,
-                               "Destroyed device backend at %s",
-                               l1[XS_WATCH_TOKEN]);
-                    rc = 0;
+                if (!sstate || atoi(sstate) == state) {
+                    /* Call handler function if present */
+                    if (handler)
+                        rc = handler(gc, l1, sstate);
                 } else {
-                    /* State is not "disconnected", continue waiting... */
+                    /* State is different than expected, continue waiting... */
                     goto start;
                 }
                 free(l1);
@@ -418,6 +417,23 @@ start:
 }
 
 /*
+ * Handler function for device destruction to be passed to
+ * libxl__wait_for_device_state
+ */
+static int destroy_device(libxl__gc *gc, char **l1, char *state)
+{
+    libxl_ctx *ctx = libxl__gc_owner(gc);
+
+    xs_unwatch(ctx->xsh, l1[0], l1[1]);
+    xs_rm(ctx->xsh, XBT_NULL, l1[XS_WATCH_TOKEN]);
+    LIBXL__LOG(ctx, LIBXL__LOG_DEBUG,
+               "Destroyed device backend at %s",
+               l1[XS_WATCH_TOKEN]);
+
+    return 0;
+}
+
+/*
  * Returns 0 (device already destroyed) or 1 (caller must
  * wait_for_dev_destroy) on success, ERROR_* on fail.
  */
@@ -458,7 +474,7 @@ retry_transaction:
         struct timeval tv;
         tv.tv_sec = LIBXL_DESTROY_TIMEOUT;
         tv.tv_usec = 0;
-        rc = wait_for_dev_destroy(gc, &tv);
+        rc = libxl__wait_for_device_state(gc, &tv, 6, destroy_device);
         if (rc < 0) /* an error or timeout occurred, clear watches */
             xs_unwatch(ctx->xsh, state_path, be_path);
         xs_rm(ctx->xsh, XBT_NULL, libxl__device_frontend_path(gc, dev));
@@ -566,7 +582,7 @@ int libxl__devices_destroy(libxl__gc *gc
         tv.tv_sec = LIBXL_DESTROY_TIMEOUT;
         tv.tv_usec = 0;
         while (n_watches > 0) {
-            if (wait_for_dev_destroy(gc, &tv) < 0) {
+            if (libxl__wait_for_device_state(gc, &tv, 6, destroy_device) < 0) {
                 /* function returned ERROR_* */
                 break;
             } else {
diff -r ec94a7e4983a -r a77bba371740 tools/libxl/libxl_internal.h
--- a/tools/libxl/libxl_internal.h      Fri Nov 18 10:46:54 2011 +0100
+++ b/tools/libxl/libxl_internal.h      Fri Nov 18 10:49:00 2011 +0100
@@ -20,6 +20,7 @@
 #include <stdint.h>
 #include <stdarg.h>
 #include <stdlib.h>
+#include <sys/time.h>
 
 #include <xs.h>
 #include <xenctrl.h>
@@ -252,6 +253,31 @@ _hidden int libxl__device_destroy(libxl_
 _hidden int libxl__devices_destroy(libxl__gc *gc, uint32_t domid, int force);
 _hidden int libxl__wait_for_backend(libxl__gc *gc, char *be_path, char *state);
 
+/* Handler for the libxl__wait_for_device_state callback */
+/*
+ * libxl__device_state_handler - Handler for the libxl__wait_for_device_state
+ * gc: allocation pool
+ * l1: array containing the path and token
+ * state: string that contains the state of the device
+ *
+ * Returns 0 on success, and < 0 on error.
+ */
+typedef int libxl__device_state_handler(libxl__gc *gc, char **l1, char *state);
+
+/*
+ * libxl__wait_for_device_state - waits a given time for a device to
+ * reach a given state
+ * gc: allocation pool
+ * tv: timeval struct containing the maximum time to wait
+ * state: state to wait for
+ * handler: callback function to execute when state is reached
+ *
+ * Returns 0 on success, and < 0 on error.
+ */
+_hidden int libxl__wait_for_device_state(libxl__gc *gc, struct timeval *tv,
+                                         int state,
+                                         libxl__device_state_handler handler);
+
 /*
  * libxl__try_phy_backend - Check if there's support for the passed
  * type of file using the PHY backend

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel