From 20e4933c478a1ca694b38fa4ac44d99e659941f5 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 22 Nov 2016 14:41:21 +0000 Subject: [PATCH] drm/i915: Stop the machine as we install the wedged submit_request handler In order to prevent a race between the old callback submitting an incomplete request and i915_gem_set_wedged() installing its nop handler, we must ensure that the swap occurs when the machine is idle (stop_machine). v2: move context lost from out of BKL. Signed-off-by: Chris Wilson Reviewed-by: Mika Kuoppala Link: http://patchwork.freedesktop.org/patch/msgid/20161122144121.7379-4-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 91f1ac30c5fa..3d4e07e9734f 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -38,6 +38,7 @@ #include #include #include +#include #include #include #include @@ -2787,6 +2788,12 @@ static void nop_submit_request(struct drm_i915_gem_request *request) static void i915_gem_cleanup_engine(struct intel_engine_cs *engine) { + /* We need to be sure that no thread is running the old callback as + * we install the nop handler (otherwise we would submit a request + * to hardware that will never complete). In order to prevent this + * race, we wait until the machine is idle before making the swap + * (using stop_machine()). + */ engine->submit_request = nop_submit_request; /* Mark all pending requests as complete so that any concurrent @@ -2817,20 +2824,29 @@ static void i915_gem_cleanup_engine(struct intel_engine_cs *engine) } } -void i915_gem_set_wedged(struct drm_i915_private *dev_priv) +static int __i915_gem_set_wedged_BKL(void *data) { + struct drm_i915_private *i915 = data; struct intel_engine_cs *engine; enum intel_engine_id id; + for_each_engine(engine, i915, id) + i915_gem_cleanup_engine(engine); + + return 0; +} + +void i915_gem_set_wedged(struct drm_i915_private *dev_priv) +{ lockdep_assert_held(&dev_priv->drm.struct_mutex); set_bit(I915_WEDGED, &dev_priv->gpu_error.flags); - i915_gem_context_lost(dev_priv); - for_each_engine(engine, dev_priv, id) - i915_gem_cleanup_engine(engine); - mod_delayed_work(dev_priv->wq, &dev_priv->gt.idle_work, 0); + stop_machine(__i915_gem_set_wedged_BKL, dev_priv, NULL); + i915_gem_context_lost(dev_priv); i915_gem_retire_requests(dev_priv); + + mod_delayed_work(dev_priv->wq, &dev_priv->gt.idle_work, 0); } static void -- 2.20.1