[Qemu-devel] [PATCH 2/2] spice display: replace private lock with qemu mutex.

[Gerd Hoffmann <kraxel@redhat.com>]

qemu_spice_create_update() must aquire the global qemu mutex to
make sure DisplayState doesn't change while we are accessing it.

Once this is in place the private lock is pretty pointless as
everything it protects is covered by the global qemu mutex now.
Drop it.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 ui/spice-display.c |   22 +++++++++-------------
 ui/spice-display.h |    1 -
 2 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/ui/spice-display.c b/ui/spice-display.c
index 6702dfd..febf411 100644
--- a/ui/spice-display.c
+++ b/ui/spice-display.c
@@ -65,10 +65,10 @@ void qemu_spice_rect_union(QXLRect *dest, const QXLRect *r)
 
 /*
  * Called from spice server thread context (via interface_get_command).
- * We do *not* hold the global qemu mutex here, so extra care is needed
- * when calling qemu functions.  Qemu interfaces used:
- *    - pflib (is re-entrant).
- *    - qemu_malloc (underlying glibc malloc is re-entrant).
+ *
+ * We must aquire the global qemu mutex here to make sure the
+ * DisplayState (+DisplaySurface) we are accessing doesn't change
+ * underneath us.
  */
 SimpleSpiceUpdate *qemu_spice_create_update(SimpleSpiceDisplay *ssd)
 {
@@ -79,11 +79,12 @@ SimpleSpiceUpdate *qemu_spice_create_update(SimpleSpiceDisplay *ssd)
     uint8_t *src, *dst;
     int by, bw, bh;
 
+    qemu_mutex_lock_iothread();
     if (qemu_spice_rect_is_empty(&ssd->dirty)) {
+        qemu_mutex_unlock_iothread();
         return NULL;
     };
 
-    pthread_mutex_lock(&ssd->lock);
     dprint(2, "%s: lr %d -> %d,  tb -> %d -> %d\n", __FUNCTION__,
            ssd->dirty.left, ssd->dirty.right,
            ssd->dirty.top, ssd->dirty.bottom);
@@ -141,7 +142,7 @@ SimpleSpiceUpdate *qemu_spice_create_update(SimpleSpiceDisplay *ssd)
     cmd->data = (intptr_t)drawable;
 
     memset(&ssd->dirty, 0, sizeof(ssd->dirty));
-    pthread_mutex_unlock(&ssd->lock);
+    qemu_mutex_unlock_iothread();
     return update;
 }
 
@@ -220,31 +221,27 @@ void qemu_spice_display_update(SimpleSpiceDisplay *ssd,
     update_area.top = y;
     update_area.bottom = y + h;
 
-    pthread_mutex_lock(&ssd->lock);
     if (qemu_spice_rect_is_empty(&ssd->dirty)) {
         ssd->notify++;
     }
     qemu_spice_rect_union(&ssd->dirty, &update_area);
-    pthread_mutex_unlock(&ssd->lock);
 }
 
 void qemu_spice_display_resize(SimpleSpiceDisplay *ssd)
 {
     dprint(1, "%s:\n", __FUNCTION__);
 
-    pthread_mutex_lock(&ssd->lock);
     memset(&ssd->dirty, 0, sizeof(ssd->dirty));
     qemu_pf_conv_put(ssd->conv);
     ssd->conv = NULL;
-    pthread_mutex_unlock(&ssd->lock);
 
+    qemu_mutex_unlock_iothread();
     qemu_spice_destroy_host_primary(ssd);
     qemu_spice_create_host_primary(ssd);
+    qemu_mutex_lock_iothread();
 
-    pthread_mutex_lock(&ssd->lock);
     memset(&ssd->dirty, 0, sizeof(ssd->dirty));
     ssd->notify++;
-    pthread_mutex_unlock(&ssd->lock);
 }
 
 void qemu_spice_display_refresh(SimpleSpiceDisplay *ssd)
@@ -399,7 +396,6 @@ void qemu_spice_display_init(DisplayState *ds)
     sdpy.ds = ds;
     sdpy.bufsize = (16 * 1024 * 1024);
     sdpy.buf = qemu_malloc(sdpy.bufsize);
-    pthread_mutex_init(&sdpy.lock, NULL);
     register_displaychangelistener(ds, &display_listener);
 
     sdpy.qxl.base.sif = &dpy_interface.base;
diff --git a/ui/spice-display.h b/ui/spice-display.h
index e17671c..aef0464 100644
--- a/ui/spice-display.h
+++ b/ui/spice-display.h
@@ -40,7 +40,6 @@ typedef struct SimpleSpiceDisplay {
     uint32_t unique;
     QemuPfConv *conv;
 
-    pthread_mutex_t lock;
     QXLRect dirty;
     int notify;
     int running;
-- 
1.7.1