xwayland: Do not keep the cursor's pixmap aroundmaster
commit8707d2835c21866ca1541bed0670352604147722
authorOlivier Fourdan <ofourdan@redhat.com>
Wed, 18 Dec 2024 15:21:44 +0000 (18 16:21 +0100)
committerOlivier Fourdan <ofourdan@redhat.com>
Fri, 20 Dec 2024 08:29:03 +0000 (20 09:29 +0100)
tree92f0194321df54efc33fd22f7cfe305809bb3f0d
parentbdacb100bf6a551bc9045f7f0048cbb99eb3db5a
xwayland: Do not keep the cursor's pixmap around

Currently, Xwayland creates a pixmap backed by shared memory buffer as
soon as an X11 cursor is realized, which is destroyed when the cursor is
eventually unrealized.

If an X11 client is leaking cursors, Xwayland will be creating new
pixmaps continuously, which will eventually cause an error once the
limit is reached, and get Xwayland killed.

However, we do not need the shared memory buffer to stay around, we
already have the buffer retention mechanism which will take care of
keeping the buffer around until the Wayland compositor is done with it,
so we could just create and destroy the pixmap as needed when setting
the cursor.

That would not fix the leak in the X11 application, yet that would
mitigate the risk of Xwayland being killed by reaching the shared memory
limits, until the client itself reaches the limit of X11 resources.

v2: Don't increase the pixmap refcnt to destroy it just after (Michel)

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Suggested-by: Michel Dänzer <michel@daenzer.net>
See-also: https://gitlab.freedesktop.org/xorg/xserver/-/issues/1773
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1754>
hw/xwayland/xwayland-cursor.c