| Message ID | 20220913161039.155964-2-janusz.krzysztofik@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915/gem: Really move i915_gem_context.link under ref protection | expand |
Hi Krzysztofik, On Tue, Sep 13, 2022 at 06:10:38PM +0200, Janusz Krzysztofik wrote: > Due to i915_perf assuming that it can use the i915_gem_context reference > to protect its i915->gem.contexts.list iteration, we need to defer removal > of the context from the list until last reference to the context is put. > However, there is a risk of triggering kernel warning on contexts list not > empty at driver release time if we deleagate that task to a worker for > i915_gem_context_release_work(), unless that work is flushed first. > Unfortunately, it is not flushed on driver release. Fix it. > > Instead of additionally calling flush_workqueue(), either directly of via > a new dedicated wrapper around it, replace last call to > i915_gem_drain_freed_objects() with existing i915_gem_drain_workqueue() > that performs both tasks. > > Fixes: 75eefd82581f ("drm/i915: Release i915_gem_context from a worker") > Suggested-by: Chris Wilson <chris@chris-wilson.co.uk> > Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com> > Cc: stable@kernel.org # v5.16+ Thanks for the fix and for taking this on you! Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> Andi > --- > drivers/gpu/drm/i915/i915_gem.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index a3373699835d7..31c197f2d8cb9 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -1191,7 +1191,8 @@ void i915_gem_driver_release(struct drm_i915_private *dev_priv) > > intel_uc_cleanup_firmwares(&to_gt(dev_priv)->uc); > > - i915_gem_drain_freed_objects(dev_priv); > + /* Flush any outstanding work, including i915_gem_context.release_work. */ > + i915_gem_drain_workqueue(dev_priv); > > drm_WARN_ON(&dev_priv->drm, !list_empty(&dev_priv->gem.contexts.list)); > } > -- > 2.25.1
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index a3373699835d7..31c197f2d8cb9 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1191,7 +1191,8 @@ void i915_gem_driver_release(struct drm_i915_private *dev_priv) intel_uc_cleanup_firmwares(&to_gt(dev_priv)->uc); - i915_gem_drain_freed_objects(dev_priv); + /* Flush any outstanding work, including i915_gem_context.release_work. */ + i915_gem_drain_workqueue(dev_priv); drm_WARN_ON(&dev_priv->drm, !list_empty(&dev_priv->gem.contexts.list)); }
Due to i915_perf assuming that it can use the i915_gem_context reference to protect its i915->gem.contexts.list iteration, we need to defer removal of the context from the list until last reference to the context is put. However, there is a risk of triggering kernel warning on contexts list not empty at driver release time if we deleagate that task to a worker for i915_gem_context_release_work(), unless that work is flushed first. Unfortunately, it is not flushed on driver release. Fix it. Instead of additionally calling flush_workqueue(), either directly of via a new dedicated wrapper around it, replace last call to i915_gem_drain_freed_objects() with existing i915_gem_drain_workqueue() that performs both tasks. Fixes: 75eefd82581f ("drm/i915: Release i915_gem_context from a worker") Suggested-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com> Cc: stable@kernel.org # v5.16+ --- drivers/gpu/drm/i915/i915_gem.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)