On Wed, 16 Feb 2022, Tvrtko Ursulin tvrtko.ursulin@linux.intel.com wrote:
On 16/02/2022 09:19, Ville Syrjälä wrote:
On Wed, Feb 16, 2022 at 11:02:06AM +0200, Jani Nikula wrote:
On Wed, 16 Feb 2022, Jiapeng Chong jiapeng.chong@linux.alibaba.com wrote:
Eliminate the follow smatch warning:
drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c:4640 guc_create_virtual() warn: assigning (-2) to unsigned variable 've->base.instance'.
drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c:4641 guc_create_virtual() warn: assigning (-2) to unsigned variable 've->base.uabi_instance'.
Reported-by: Abaci Robot abaci@linux.alibaba.com Signed-off-by: Jiapeng Chong jiapeng.chong@linux.alibaba.com
The report seems to be valid, but I don't think this is the fix.
Where do we even check for invalid instance/uabi_instance in code?
The whole thing seems rather poorly documented as there's a matching uabi struct with __u16's and the negative values are defined right there in the uapi header as well.
Negative ones are exception values to be used in conjunction with the virtual engine uapi (see "DOC: Virtual Engine uAPI" and also comment next to I915_CONTEXT_PARAM_ENGINES).
AFAIK assigning negative int to unsigned int is defined and fine.
Compiler does warn on comparisons which is why we have:
./gem/i915_gem_busy.c: if (id == (u16)I915_ENGINE_CLASS_INVALID) ./gem/i915_gem_busy.c: if (id == (u16)I915_ENGINE_CLASS_INVALID) ./gem/i915_gem_context.c: if (ci.engine_class == (u16)I915_ENGINE_CLASS_INVALID && ./gem/i915_gem_context.c: ci.engine_instance == (u16)I915_ENGINE_CLASS_INVALID_NONE)
So I think no action needed here.
We never check instance or uabi_instance members against I915_ENGINE_CLASS_INVALID_VIRTUAL anywhere.
BR, Jani.
Regards,
Tvrtko
BR, Jani.
drivers/gpu/drm/i915/gt/intel_engine_types.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index 36365bdbe1ee..dc7cc06c68e7 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -328,10 +328,10 @@ struct intel_engine_cs { intel_engine_mask_t logical_mask; u8 class;
- u8 instance;
- s8 instance;
u16 uabi_class;
- u16 uabi_instance;
- s16 uabi_instance;
u32 uabi_capabilities; u32 context_size;
-- Jani Nikula, Intel Open Source Graphics Center