On Thu, Feb 12, 2015 at 10:43:44AM +0100, Daniel Vetter wrote: > On Thu, Feb 12, 2015 at 07:53:18AM +0000, Chris Wilson wrote: > > When we walk the list of vma, or even for protecting against concurrent > > framebuffer creation, we must hold the struct_mutex or else a second > > thread can corrupt the list as we walk it. > > > > Fixes regression from > > commit d7f46fc4e7323887494db13f063a8e59861fefb0 > > Author: Ben Widawsky <[email protected]> > > Date: Fri Dec 6 14:10:55 2013 -0800 > > > > drm/i915: Make pin count per VMA > > > > References: https://bugs.freedesktop.org/show_bug.cgi?id=89085 > > Signed-off-by: Chris Wilson <[email protected]> > > --- > > drivers/gpu/drm/i915/i915_gem_tiling.c | 7 ++++--- > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c > > b/drivers/gpu/drm/i915/i915_gem_tiling.c > > index 7a24bd1a51f6..6377b22269ad 100644 > > --- a/drivers/gpu/drm/i915/i915_gem_tiling.c > > +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c > > @@ -335,9 +335,10 @@ i915_gem_set_tiling(struct drm_device *dev, void *data, > > return -EINVAL; > > } > > > > + mutex_lock(&dev->struct_mutex); > > if (i915_gem_obj_is_pinned(obj) || obj->framebuffer_references) { > > Since the removal of userspace pinning we shouldn't be able to see pinned > objects here which are _not_ framebuffers too. But we still need the lock > for synchronization and to avoid races, but perhaps we could drop the list > walk?
It would be possible for us to catch an object in the process of being executed. More so, we *only* care about GTT pinning here, but still we need to the lock to prevent that disappearing underneath us. > Either way this is > > Reviewed-by: Daniel Vetter <[email protected]> > Cc: [email protected] (we have some vague evidence that it blows up > at last) > > I've also audited all the other callers of is_pinned, the only other > suspicious one is the one in capture_bo. Perhaps we should also move that > over to obj->framebuffer_references? We killed that over a year ago in the conversion of error capture over to vma for full-ppgtt prepartion... Right? -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
