From 6960d9cfc721d9e577631b9057c07eecea8bdc0f Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 4 Apr 2019 11:19:14 +0100 Subject: [PATCH] drm/i915: Be precise in types for i915_gem_busy Mixing u8 and -1u together leads to zero-extended integer expansion, and comparing 0x000000ff against 0xffffffff, causing us to report a mixed uabi-class request as not busy. The input flag is a u8, and we want to generate a u32 uABI response, mark our functions so. Fixes: c8b502422bfe ("drm/i915: Remove last traces of exec-id (GEM_BUSY)") Testcase: igt/gem_exec_balance/busy Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20190404101914.7231-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index bf594a5e88bc..f25a1ba24927 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3841,16 +3841,16 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj, return vma; } -static __always_inline unsigned int __busy_read_flag(unsigned int id) +static __always_inline u32 __busy_read_flag(u8 id) { - if (id == I915_ENGINE_CLASS_INVALID) - return 0xffff0000; + if (id == (u8)I915_ENGINE_CLASS_INVALID) + return 0xffff0000u; GEM_BUG_ON(id >= 16); - return 0x10000 << id; + return 0x10000u << id; } -static __always_inline unsigned int __busy_write_id(unsigned int id) +static __always_inline u32 __busy_write_id(u8 id) { /* * The uABI guarantees an active writer is also amongst the read @@ -3861,15 +3861,14 @@ static __always_inline unsigned int __busy_write_id(unsigned int id) * last_read - hence we always set both read and write busy for * last_write. */ - if (id == I915_ENGINE_CLASS_INVALID) - return 0xffffffff; + if (id == (u8)I915_ENGINE_CLASS_INVALID) + return 0xffffffffu; return (id + 1) | __busy_read_flag(id); } static __always_inline unsigned int -__busy_set_if_active(const struct dma_fence *fence, - unsigned int (*flag)(unsigned int id)) +__busy_set_if_active(const struct dma_fence *fence, u32 (*flag)(u8 id)) { const struct i915_request *rq; @@ -3889,6 +3888,8 @@ __busy_set_if_active(const struct dma_fence *fence, if (i915_request_completed(rq)) return 0; + /* Beware type-expansion follies! */ + BUILD_BUG_ON(!typecheck(u8, rq->engine->uabi_class)); return flag(rq->engine->uabi_class); } -- 2.39.5