From: Daniel Vetter <daniel@ffwll.ch>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Remove locking for get-caching query
Date: Thu, 7 May 2015 15:22:41 +0200 [thread overview]
Message-ID: <20150507132241.GC30184@phenom.ffwll.local> (raw)
In-Reply-To: <1430997295-8336-1-git-send-email-chris@chris-wilson.co.uk>
On Thu, May 07, 2015 at 12:14:55PM +0100, Chris Wilson wrote:
> Reading a single value from the object, the locking only provides futile
> protection against userspace races. The locking is useless so remove it.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 17 ++++-------------
> 1 file changed, 4 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 2b2b74dbb446..d071d0af2a6c 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3983,17 +3983,10 @@ int i915_gem_get_caching_ioctl(struct drm_device *dev, void *data,
> {
> struct drm_i915_gem_caching *args = data;
> struct drm_i915_gem_object *obj;
> - int ret;
> -
> - ret = i915_mutex_lock_interruptible(dev);
> - if (ret)
> - return ret;
>
> obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
> - if (&obj->base == NULL) {
> - ret = -ENOENT;
> - goto unlock;
> - }
> + if (&obj->base == NULL)
> + return -ENOENT;
>
> switch (obj->cache_level) {
Wrap this in ACCESS_ONCE, just for documentation purpose? Can do while
applying if you ack.
-Daniel
> case I915_CACHE_LLC:
> @@ -4010,10 +4003,8 @@ int i915_gem_get_caching_ioctl(struct drm_device *dev, void *data,
> break;
> }
>
> - drm_gem_object_unreference(&obj->base);
> -unlock:
> - mutex_unlock(&dev->struct_mutex);
> - return ret;
> + drm_gem_object_unreference_unlocked(&obj->base);
> + return 0;
> }
>
> int i915_gem_set_caching_ioctl(struct drm_device *dev, void *data,
> --
> 2.1.4
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
next prev parent reply other threads:[~2015-05-07 13:20 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-07 11:14 [PATCH] drm/i915: Remove locking for get-caching query Chris Wilson
2015-05-07 13:22 ` Daniel Vetter [this message]
2015-05-07 13:22 ` Chris Wilson
2015-05-07 13:45 ` Mika Kuoppala
2015-05-08 6:39 ` shuang.he
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