[Intel-gfx] [PATCH] drm/i915: fix pm refcounting on fence error in execbuf

[Chris Wilson]

On Fri, Feb 03, 2017 at 10:55:32PM +0000, Chris Wilson wrote:
> On Fri, Feb 03, 2017 at 02:45:29PM -0800, Daniele Ceraolo Spurio wrote:
> > Fences are creted/checked before the pm ref is taken, so if we jump to
> > pre_mutex_err we will uncorrectly call intel_runtime_pm_put.
> > 
> > Fixes: fec0445caa27 (drm/i915: Support explicit fencing for execbuf)
> > Testcase: igt/gem_exec_params
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> 
> Sigh. The tree I was using has this:
> 
> 	if (args->flags & I915_EXEC_FENCE_IN) {
> 		in_fence = sync_file_get_fence(lower_32_bits(args->rsvd2));
> 		if (!in_fence)
> 			return -EINVAL;
> 	}
> 
> 	if (args->flags & I915_EXEC_FENCE_OUT) {
> 		out_fence_fd = get_unused_fd_flags(O_CLOEXEC);
> 		if (out_fence_fd < 0) {
> 			ret = out_fence_fd;
> 			goto err_in_fence;
> 		}
> 	}
> 
> 	...
> 
> 	err_unlock:
> 		mutex_unlock(&dev->struct_mutex);
> 	err_rpm:
> 		intel_runtime_pm_put(eb.i915);
> 		eb_destroy(&eb);
> 		if (out_fence_fd != -1)
> 			put_unused_fd(out_fence_fd);
> 	err_in_fence:
> 		dma_fence_put(in_fence);
> 		return ret;
> 	}
> 
> Transforming the unwind sequence to match would be appreciated.

Just in case I wasn't clear, just do the unwind gotos for the out_fence,
i.e add err_in_fence:
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre