On 01/09/2016 11:43 AM, Daniel Vetter wrote: > On Fri, Jan 8, 2016 at 9:53 PM, Thomas Hellstrom <thellstrom@xxxxxxxxxx> wrote: >> On 01/08/2016 09:36 PM, Daniel Vetter wrote: >>> Again since the drm core takes care of event unlinking/disarming this >>> is now just needless code. >>> >>> Cc: Thomas Hellström <thellstrom@xxxxxxxxxx> >>> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> >> Hmm, >> >> IIRC this is actually a list of events that core drm is not aware of >> yet. They sit on this list waiting for a fence to pass and are then >> transferred to core drm.... > Yes I know. Earlier patches in the series extract new core functions > to setup/tear down such events and send them out, which is what's > needed to make this trick possible. Exynos similarly uses events > similarly, and is also converted. Same for nouveau it seems, but there > the code doesn't use the reserve/send split, so I'm unclear > how/whether at all it correctly handles this race. > -Daniel Ah. Hmm I should've looked more closely at the rest of the series. In any case, this particular patch leaves, from what I can tell, the eaction fpriv list intact when it is later freed in postclose, which is bad. Also each eaction is left with a dangling pointer to a freed pending event which is also very bad since that pointer will be dereferenced as soon as the fence's seqno has passed. So as far as i can tell, this function needs to remain except for the event destruction. Thinking of it, this must be a problem that is more general problem than for vmwgfx only, I mean, unless the driver traverses all core pending event list to find relevant pending events to process, something in the driver must actually point to the pending event (be it a pointer in the fence object or, as in the vmwgfx case, a pointer in the fence action object) and that pointer must somehow be invalidated when the pending event is freed... Which also brings up a question, where are the pending events actually destroyed? I can see they are unlinked in drm_fops.c. /Thomas _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
