| Message ID | 1300220228-27423-5-git-send-email-alevy@redhat.com |
|---|---|
| State | New |
| Headers | show |
Hi, As discussed on irc I think we need to look into this and see if we can fix it properly while at it. IOW to be continued... Regards, Hans On 03/15/2011 09:17 PM, Alon Levy wrote: > Dropping the locks prevents a deadlock when running with -sdl or -vnc > in addition to -spice. > > When server calls get_cursor_command, and we have an active ds > cursor related callback in non vga mode, we need to lock to prevent > the iothread (via sdl/vnc gui_update timer) from touching the ds as well. > > Currently (-sdl/-vnc) + -spice seems to work, due to dropping the locking in > qxl-render.c:qxl_render_cursor, but this is just waiting to break because of > touching the cursor from two threads without any locking. > --- > hw/qxl-render.c | 13 +++++++++---- > 1 files changed, 9 insertions(+), 4 deletions(-) > > diff --git a/hw/qxl-render.c b/hw/qxl-render.c > index 58965e0..1065388 100644 > --- a/hw/qxl-render.c > +++ b/hw/qxl-render.c > @@ -209,18 +209,23 @@ void qxl_render_cursor(PCIQXLDevice *qxl, QXLCommandExt *ext) > if (c == NULL) { > c = cursor_builtin_left_ptr(); > } > - qemu_mutex_lock_iothread(); > + /* TODO: move this operation to iothread via pipe > + * we can't use the global lock here without dropping it > + * in gui_update (vl.c), or we get a dead lock (gui_update > + * calls dispatcher, waiting on pipe read, and spice server calls > + * this function, waiting on the lock that iothread is holding). > + * But when used with sdl this calls sdl.c:sdl_mouse_define, which > + * afaict must be locked or called from iothread. Moving to iothread > + * seems easiest from correctness pov. */ > qxl->ssd.ds->cursor_define(c); > qxl->ssd.ds->mouse_set(x, y, 1); > - qemu_mutex_unlock_iothread(); > cursor_put(c); > break; > case QXL_CURSOR_MOVE: > x = cmd->u.position.x; > y = cmd->u.position.y; > - qemu_mutex_lock_iothread(); > + /* TODO: move this operation to iothread via pipe. See comment above */ > qxl->ssd.ds->mouse_set(x, y, 1); > - qemu_mutex_unlock_iothread(); > break; > } > }
diff --git a/hw/qxl-render.c b/hw/qxl-render.c index 58965e0..1065388 100644 --- a/hw/qxl-render.c +++ b/hw/qxl-render.c @@ -209,18 +209,23 @@ void qxl_render_cursor(PCIQXLDevice *qxl, QXLCommandExt *ext) if (c == NULL) { c = cursor_builtin_left_ptr(); } - qemu_mutex_lock_iothread(); + /* TODO: move this operation to iothread via pipe + * we can't use the global lock here without dropping it + * in gui_update (vl.c), or we get a dead lock (gui_update + * calls dispatcher, waiting on pipe read, and spice server calls + * this function, waiting on the lock that iothread is holding). + * But when used with sdl this calls sdl.c:sdl_mouse_define, which + * afaict must be locked or called from iothread. Moving to iothread + * seems easiest from correctness pov. */ qxl->ssd.ds->cursor_define(c); qxl->ssd.ds->mouse_set(x, y, 1); - qemu_mutex_unlock_iothread(); cursor_put(c); break; case QXL_CURSOR_MOVE: x = cmd->u.position.x; y = cmd->u.position.y; - qemu_mutex_lock_iothread(); + /* TODO: move this operation to iothread via pipe. See comment above */ qxl->ssd.ds->mouse_set(x, y, 1); - qemu_mutex_unlock_iothread(); break; } }