drm: Release filp before global lock
The file is not part of the global drm resource and can be released prior to take the global mutex to drop the open_count (and potentially close) the drm device. As the global mutex is indeed global, not only within the device but across devices, a slow file release mechanism can bottleneck the entire system. However, inside drm_close_helper() there are a number of dev->driver callbacks that take the drm_device as the first parameter... Worryingly some of those callbacks may be (implicitly) depending on the global mutex. v2: Drop the debug message for the open-count, it's included with the drm_file_free() debug message -- and for good measure make that up as reading outside of the mutex. v3: Separate the calling of the filp cleanup outside of drm_global_mutex into a new drm_release_noglobal() hook, so that we can phase the transition. drm/savage relies on the global mutex, and there may be more, so be cautious. Signed-off-by:Chris Wilson <chris@chris-wilson.co.uk> Cc: Thomas Hellström (VMware) <thomas_os@shipmail.org> Reviewed-by:
Thomas Hellström (VMware) <thomas_os@shipmail.org> Link: https://patchwork.freedesktop.org/patch/msgid/20200124125627.125042-1-chris@chris-wilson.co.uk
parent
c2d4290b
Please register or sign in to comment