[Qemu-devel] [PATCH v3 3/4] qxl/spice: remove qemu_mutex_{un, }lock_iothread around dispatcher

[Alon Levy <alevy@redhat.com>]

with the previous patch making sure get_command no longer needs to lock,
there is no reason to drop the qemu iothread mutex in qxl.c and in
ui/spice-display.c

The only location where the lock remains are the cursor related callbacks,
that path is currently broken. It is only triggered if running spice and sdl,
which is broken already before that.
---
 hw/qxl.c           |    8 --------
 ui/spice-display.c |   19 +++----------------
 2 files changed, 3 insertions(+), 24 deletions(-)

diff --git a/hw/qxl.c b/hw/qxl.c
index 64580f1..cf3c938 100644
--- a/hw/qxl.c
+++ b/hw/qxl.c
@@ -670,10 +670,8 @@ static void qxl_hard_reset(PCIQXLDevice *d, int loadvm)
     dprint(d, 1, "%s: start%s\n", __FUNCTION__,
            loadvm ? " (loadvm)" : "");
 
-    qemu_mutex_unlock_iothread();
     d->ssd.worker->reset_cursor(d->ssd.worker);
     d->ssd.worker->reset_image_cache(d->ssd.worker);
-    qemu_mutex_lock_iothread();
     qxl_reset_surfaces(d);
     qxl_reset_memslots(d);
 
@@ -803,9 +801,7 @@ static void qxl_reset_surfaces(PCIQXLDevice *d)
 {
     dprint(d, 1, "%s:\n", __FUNCTION__);
     d->mode = QXL_MODE_UNDEFINED;
-    qemu_mutex_unlock_iothread();
     d->ssd.worker->destroy_surfaces(d->ssd.worker);
-    qemu_mutex_lock_iothread();
     memset(&d->guest_surfaces.cmds, 0, sizeof(d->guest_surfaces.cmds));
 }
 
@@ -874,9 +870,7 @@ static void qxl_destroy_primary(PCIQXLDevice *d)
     dprint(d, 1, "%s\n", __FUNCTION__);
 
     d->mode = QXL_MODE_UNDEFINED;
-    qemu_mutex_unlock_iothread();
     d->ssd.worker->destroy_primary_surface(d->ssd.worker, 0);
-    qemu_mutex_lock_iothread();
 }
 
 static void qxl_set_mode(PCIQXLDevice *d, int modenr, int loadvm)
@@ -946,10 +940,8 @@ static void ioport_write(void *opaque, uint32_t addr, uint32_t val)
     case QXL_IO_UPDATE_AREA:
     {
         QXLRect update = d->ram->update_area;
-        qemu_mutex_unlock_iothread();
         d->ssd.worker->update_area(d->ssd.worker, d->ram->update_surface,
                                    &update, NULL, 0, 0);
-        qemu_mutex_lock_iothread();
         break;
     }
     case QXL_IO_NOTIFY_CMD:
diff --git a/ui/spice-display.c b/ui/spice-display.c
index bdd14b8..ecb22cc 100644
--- a/ui/spice-display.c
+++ b/ui/spice-display.c
@@ -62,13 +62,7 @@ void qemu_spice_rect_union(QXLRect *dest, const QXLRect *r)
     dest->right = MAX(dest->right, r->right);
 }
 
-/*
- * Called from spice server thread context (via interface_get_command).
- *
- * We must aquire the global qemu mutex here to make sure the
- * DisplayState (+DisplaySurface) we are accessing doesn't change
- * underneath us.
- */
+/* Called from io-thread context (via pipe_read) */
 SimpleSpiceUpdate *qemu_spice_create_update(SimpleSpiceDisplay *ssd)
 {
     SimpleSpiceUpdate *update;
@@ -78,9 +72,7 @@ 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;
     };
 
@@ -141,7 +133,6 @@ SimpleSpiceUpdate *qemu_spice_create_update(SimpleSpiceDisplay *ssd)
     cmd->data = (intptr_t)drawable;
 
     memset(&ssd->dirty, 0, sizeof(ssd->dirty));
-    qemu_mutex_unlock_iothread();
     return update;
 }
 
@@ -169,6 +160,7 @@ void qemu_spice_create_host_memslot(SimpleSpiceDisplay *ssd)
     ssd->worker->add_memslot(ssd->worker, &memslot);
 }
 
+/* called from iothread (main) or a vcpu-thread */
 void qemu_spice_create_host_primary(SimpleSpiceDisplay *ssd)
 {
     QXLDevSurfaceCreate surface;
@@ -186,18 +178,14 @@ void qemu_spice_create_host_primary(SimpleSpiceDisplay *ssd)
     surface.mem        = (intptr_t)ssd->buf;
     surface.group_id   = MEMSLOT_GROUP_HOST;
 
-    qemu_mutex_unlock_iothread();
     ssd->worker->create_primary_surface(ssd->worker, 0, &surface);
-    qemu_mutex_lock_iothread();
 }
 
 void qemu_spice_destroy_host_primary(SimpleSpiceDisplay *ssd)
 {
     dprint(1, "%s:\n", __FUNCTION__);
 
-    qemu_mutex_unlock_iothread();
     ssd->worker->destroy_primary_surface(ssd->worker, 0);
-    qemu_mutex_lock_iothread();
 }
 
 void qemu_spice_vm_change_state_handler(void *opaque, int running, int reason)
@@ -207,9 +195,7 @@ void qemu_spice_vm_change_state_handler(void *opaque, int running, int reason)
     if (running) {
         ssd->worker->start(ssd->worker);
     } else {
-        qemu_mutex_unlock_iothread();
         ssd->worker->stop(ssd->worker);
-        qemu_mutex_lock_iothread();
     }
     ssd->running = running;
 }
@@ -233,6 +219,7 @@ void qemu_spice_display_update(SimpleSpiceDisplay *ssd,
     qemu_spice_rect_union(&ssd->dirty, &update_area);
 }
 
+/* called only from iothread (main) */
 void qemu_spice_display_resize(SimpleSpiceDisplay *ssd)
 {
     dprint(1, "%s:\n", __FUNCTION__);
-- 
1.7.4.1