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spice-display: fix qemu_spice_cursor_refresh_bh locking

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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@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20180720063109.4631-3-pbonzini@redhat.com

[ kraxel: fix dpy_cursor_define() call ]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Paolo Bonzini 2018-07-20 08:31:09 +02:00 committed by Gerd Hoffmann
parent 2480f41e68
commit 006bf4641b
1 changed files with 22 additions and 16 deletions
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38
ui/spice-display.c
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@ -450,27 +450,33 @@ void qemu_spice_display_switch(SimpleSpiceDisplay *ssd,
qemu_mutex_unlock(&ssd->lock);
}
static void qemu_spice_cursor_refresh_unlocked(SimpleSpiceDisplay *ssd)
{
if (ssd->cursor) {
assert(ssd->dcl.con);
dpy_cursor_define(ssd->dcl.con, ssd->cursor);
}
if (ssd->mouse_x != -1 && ssd->mouse_y != -1) {
assert(ssd->dcl.con);
dpy_mouse_set(ssd->dcl.con, ssd->mouse_x, ssd->mouse_y, 1);
ssd->mouse_x = -1;
ssd->mouse_y = -1;
}
}
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);
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, c);
qemu_mutex_lock(&ssd->lock);
cursor_put(c);
}
if (ssd->mouse_x != -1 && ssd->mouse_y != -1) {
int x, y;
assert(ssd->dcl.con);
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_display_refresh(SimpleSpiceDisplay *ssd)