Quoting Thomas Hellström (VMware) (2020-01-24 13:37:47) > On 1/24/20 2:01 PM, Chris Wilson wrote: > > Since drm_global_mutex is a true global mutex across devices, we don't > > want to acquire it unless absolutely necessary. For maintaining the > > device local open_count, we can use atomic operations on the counter > > itself, except when making the transition to/from 0. Here, we tackle the > > easy portion of delaying acquiring the drm_global_mutex for the final > > release by using atomic_dec_and_mutex_lock(), leaving the global > > serialisation across the device opens. > > > > Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk> > > Cc: Thomas Hellström (VMware) <thomas...@shipmail.org> > > For the series: > > Reviewed-by: Thomas Hellström <thellst...@vmware.com> > > Now the only remaining (though pre-existing) problem I can see is that > there is no corresponding mutex lock in drm_open() so that firstopen > might race with lastclose.. Or I might be missing something..
iirc, it's a complicated dance where it goes through drm_stub_open() first which acquires the drm_global_mutex. -Chris _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
