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drm/i915: Fix RPS pointer passed from wait_ioctl to i915_wait_request

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In commit 2e1b873072 [v4.2]
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Mon Apr 27 13:41:22 2015 +0100

    drm/i915: Convert RPS tracking to a intel_rps_client struct

we converted the __i915_wait_request() to take a new intel_rps_client
struct (rather than having to pass fake drm_i915_file_private structs).
However, due to use of passing a void pointer, I didn't spot one
callsite in wait-ioctl was passing the wrong pointer.

Fwiw, the impact of this bug is zero. Along the rps path, we always
first call list_empty(rps) which when we pass in the wrong pointer
always evaluates to false and we return early and never chase the
invalid pointers.

The user visible impact is then wait-ioctl doesn't get the same
waitboosting as the other interfaces (set-domain, throttle), which is a
performance concern for the *very* few users of the wait interface.
There is also a libdrm_intel patch to use the wait-ioctl for
drm_intel_bo_wait_rendering() if anyone feels inclined to review
libdrm_intel patches.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
[danvet: Add Chris' explanation for why the impact of this is pretty
close to 0.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Chris Wilson 2015-12-02 09:13:46 +00:00 committed by Daniel Vetter
parent d8578836ad
commit b6aa087361
1 changed files with 1 additions and 1 deletions
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2
drivers/gpu/drm/i915/i915_gem.c
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@ -3064,7 +3064,7 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
if (ret == 0)
ret = __i915_wait_request(req[i], reset_counter, true,
args->timeout_ns > 0 ? &args->timeout_ns : NULL,
file->driver_priv);
to_rps_client(file));
i915_gem_request_unreference__unlocked(req[i]);
}
return ret;