[libvirt] [PULL 08/12] spice-display: fix qemu_spice_cursor_refresh_bh locking

From: Paolo Bonzini <pbonzini(a)redhat.com&gt; spice-display should not call the ui/console.c functions dpy_cursor_define and dpy_moues_set with the SimpleSpiceDisplay lock taken. That will cause a deadlock, because the DisplayChangeListener callbacks will take the lock again. It is also in general a bad idea to invoke generic callbacks with a lock taken, because it can cause AB-BA deadlocks in the long run. The only thing that requires care is that the cursor may disappear as soon as the mutex is released, so you need an extra cursor_get/cursor_put pair. Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com&gt; Reviewed-by: Marc-André Lureau <marcandre.lureau(a)redhat.com&gt; Message-id: 20180720063109.4631-3-pbonzini(a)redhat.com Signed-off-by: Gerd Hoffmann <kraxel(a)redhat.com&gt; --- ui/spice-display.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) diff --git a/ui/spice-display.c b/ui/spice-display.c index 46df673cd7..f1d341091a 100644 --- a/ui/spice-display.c +++ b/ui/spice-display.c @@ -450,29 +450,35 @@ void qemu_spice_display_switch(SimpleSpiceDisplay *ssd, qemu_mutex_unlock(&ssd->lock); } -static void qemu_spice_cursor_refresh_unlocked(SimpleSpiceDisplay *ssd) +void qemu_spice_cursor_refresh_bh(void *opaque) { + SimpleSpiceDisplay *ssd = opaque; + + qemu_mutex_lock(&ssd->lock); if (ssd->cursor) { + QEMUCursor *c = ssd->cursor; assert(ssd->dcl.con); + cursor_get(c); + qemu_mutex_unlock(&ssd->lock); dpy_cursor_define(ssd->dcl.con, ssd->cursor); + qemu_mutex_lock(&ssd->lock); + cursor_put(c); } + if (ssd->mouse_x != -1 && ssd->mouse_y != -1) { + int x, y; assert(ssd->dcl.con); - dpy_mouse_set(ssd->dcl.con, ssd->mouse_x, ssd->mouse_y, 1); + x = ssd->mouse_x; + y = ssd->mouse_y; ssd->mouse_x = -1; ssd->mouse_y = -1; + qemu_mutex_unlock(&ssd->lock); + dpy_mouse_set(ssd->dcl.con, x, y, 1); + } else { + qemu_mutex_unlock(&ssd->lock); } } -void qemu_spice_cursor_refresh_bh(void *opaque) -{ - SimpleSpiceDisplay *ssd = opaque; - - qemu_mutex_lock(&ssd->lock); - qemu_spice_cursor_refresh_unlocked(ssd); - qemu_mutex_unlock(&ssd->lock); -} - void qemu_spice_display_refresh(SimpleSpiceDisplay *ssd) { graphic_hw_update(ssd->dcl.con); -- 2.9.3