[Spice-devel] [PATCH v7 01/14] win-usb-dev: Fix device (un)plug notification handler

[Dmitry Fleytman]

This patch fixes device list change notification handing
logic for cases when more than one device being plugged
or unplugged simultaneously.

The simplest way to reproduce the problematic scenario
is (un)plugging of a usb HUB with a few devices inserted.

Signed-off-by: Dmitry Fleytman <dmitry at daynix.com>
---
 src/win-usb-dev.c | 93 +++++++++++++++++--------------------------------------
 1 file changed, 28 insertions(+), 65 deletions(-)

diff --git a/src/win-usb-dev.c b/src/win-usb-dev.c
index 1e4b2d6..2cb3108 100644
--- a/src/win-usb-dev.c
+++ b/src/win-usb-dev.c
@@ -34,7 +34,6 @@
 
 struct _GUdevClientPrivate {
     libusb_context *ctx;
-    gssize udev_list_size;
     GList *udev_list;
     HWND hwnd;
 };
@@ -196,9 +195,7 @@ g_udev_client_initable_init(GInitable *initable, GCancellable *cancellable,
     }
 
     /* get initial device list */
-    priv->udev_list_size = g_udev_client_list_devices(self, &priv->udev_list,
-                                                      err, __FUNCTION__);
-    if (priv->udev_list_size < 0) {
+    if (g_udev_client_list_devices(self, &priv->udev_list, err, __FUNCTION__) < 0) {
         goto g_udev_client_init_failed;
     }
 
@@ -319,94 +316,60 @@ static gboolean get_usb_dev_info(libusb_device *dev, GUdevDeviceInfo *udevinfo)
 }
 
 /* Only vid:pid are compared */
-static gboolean gudev_devices_are_equal(GUdevDevice *a, GUdevDevice *b)
+static gint gudev_devices_differ(gconstpointer a, gconstpointer b)
 {
     GUdevDeviceInfo *ai, *bi;
     gboolean same_vid;
     gboolean same_pid;
 
-    ai = a->priv->udevinfo;
-    bi = b->priv->udevinfo;
+    ai = G_UDEV_DEVICE(a)->priv->udevinfo;
+    bi = G_UDEV_DEVICE(b)->priv->udevinfo;
 
     same_vid  = (ai->vid == bi->vid);
     same_pid  = (ai->pid == bi->pid);
 
-    return (same_pid && same_vid);
+    return (same_pid && same_vid) ? 0 : -1;
 }
 
+static void notify_dev_state_change(GUdevClient *self,
+                                    GList *old_list,
+                                    GList *new_list,
+                                    const gchar *action)
+{
+    GList *dev;
+
+    for (dev = g_list_first(old_list); dev != NULL; dev = g_list_next(dev)) {
+        if (g_list_find_custom(new_list, dev->data, gudev_devices_differ) == NULL) {
+            /* Found a device that changed its state */
+            g_udev_device_print(dev->data, action);
+            g_signal_emit(self, signals[UEVENT_SIGNAL], 0, action, dev->data);
+        }
+    }
+}
 
-/* Assumes each event stands for a single device change (at most) */
 static void handle_dev_change(GUdevClient *self)
 {
     GUdevClientPrivate *priv = self->priv;
-    GUdevDevice *changed_dev = NULL;
-    ssize_t dev_count;
-    int is_dev_change;
     GError *err = NULL;
     GList *now_devs = NULL;
-    GList *llist, *slist; /* long-list and short-list*/
-    GList *lit, *sit; /* iterators for long-list and short-list */
-    GUdevDevice *ldev, *sdev; /* devices on long-list and short-list */
-
-    dev_count = g_udev_client_list_devices(self, &now_devs, &err,
-                                           __FUNCTION__);
-    g_return_if_fail(dev_count >= 0);
 
-    SPICE_DEBUG("number of current devices %"G_GSSIZE_FORMAT
-                ", I know about %"G_GSSIZE_FORMAT" devices",
-                dev_count, priv->udev_list_size);
-
-    is_dev_change = dev_count - priv->udev_list_size;
-    if (is_dev_change == 0) {
-        g_udev_client_free_device_list(&now_devs);
+    if(g_udev_client_list_devices(self, &now_devs, &err, __FUNCTION__) < 0) {
+        g_warning("could not retrieve device list");
         return;
     }
 
-    if (is_dev_change > 0) {
-        llist  = now_devs;
-        slist = priv->udev_list;
-    } else {
-        llist = priv->udev_list;
-        slist  = now_devs;
-    }
-
-    g_udev_device_print_list(llist, "handle_dev_change: long list:");
-    g_udev_device_print_list(slist, "handle_dev_change: short list:");
-
-    /* Go over the longer list */
-    for (lit = g_list_first(llist); lit != NULL; lit=g_list_next(lit)) {
-        ldev = lit->data;
-        /* Look for dev in the shorther list */
-        for (sit = g_list_first(slist); sit != NULL; sit=g_list_next(sit)) {
-            sdev = sit->data;
-            if (gudev_devices_are_equal(ldev, sdev))
-                break;
-        }
-        if (sit == NULL) {
-            /* Found a device which appears only in the longer list */
-            changed_dev = ldev;
-            break;
-        }
-    }
+    g_udev_device_print_list(now_devs, "handle_dev_change: current list:");
+    g_udev_device_print_list(priv->udev_list, "handle_dev_change: previous list:");
 
-    if (!changed_dev) {
-        g_warning("couldn't find any device change");
-        goto leave;
-    }
+    /* Unregister devices that are not present anymore */
+    notify_dev_state_change(self, priv->udev_list, now_devs, "remove");
 
-    if (is_dev_change > 0) {
-        g_udev_device_print(changed_dev, ">>> USB device inserted");
-        g_signal_emit(self, signals[UEVENT_SIGNAL], 0, "add", changed_dev);
-    } else {
-        g_udev_device_print(changed_dev, "<<< USB device removed");
-        g_signal_emit(self, signals[UEVENT_SIGNAL], 0, "remove", changed_dev);
-    }
+    /* Register newly inserted devices */
+    notify_dev_state_change(self, now_devs, priv->udev_list, "add");
 
-leave:
     /* keep most recent info: free previous list, and keep current list */
     g_udev_client_free_device_list(&priv->udev_list);
     priv->udev_list = now_devs;
-    priv->udev_list_size = dev_count;
 }
 
 static LRESULT CALLBACK wnd_proc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam)
-- 
2.5.0