Messages in this thread | | | Date | Fri, 18 Mar 2022 11:21:59 +0100 | Subject | Re: [PATCH 1/2 RESEND] drm/bridge: parade-ps8640: avoid race condition on driver unbinding | From | AngeloGioacchino Del Regno <> |
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Il 11/03/22 10:34, Ricardo Cañuelo ha scritto: > When unbinding a DRM master driver there's a race condition that > sometimes results in an invalid vm access when userspace (gnome-shell) > issues a DRM_IOCTL_MODE_GETCONNECTOR ioctl right after a bridge has been > removed from an encoder's bridge chain. > > This means that once a bridge has been disabled and gone through > ps8640_post_disable(), if ps8640_bridge_get_edid() runs afterwards as a > result of that ioctl call it will call drm_bridge_chain_pre_enable() > and drm_bridge_chain_post_disable() again in a bridge that has been > already detached. > > Setting `ps_bridge->pre_enabled = false` at a later stage of the > bringdown path and calling drm_bridge_chain_pre_enable() inside > ps8640_bridge_get_edid() only if needed avoid this, although a proper > subsystem-wide fix would be the proper solution, since the same type of > race conditions might happen somewhere else. > > Tested on an Acer Chromebook R13 (Elm, MT8173) with Debian Sid. > > Signed-off-by: Ricardo Cañuelo <ricardo.canuelo@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> --- > drivers/gpu/drm/bridge/parade-ps8640.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) >
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