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drm/msm: Drop struct_mutex in madvise path

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The obj->lock is sufficient for what we need.

This *does* have the implication that userspace can try to shoot
themselves in the foot by racing madvise(DONTNEED) with submit.  But
the result will be about the same if they did madvise(DONTNEED) before
the submit ioctl, ie. they might not get want they want if they race
with shrinker.  But iova fault handling is robust enough, so userspace
is only shooting it's own foot.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Signed-off-by: Rob Clark <robdclark@chromium.org>
This commit is contained in:
Rob Clark 2020-10-23 09:51:22 -07:00
parent c951a9b284
commit f92f026a48
3 changed files with 3 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

11
drivers/gpu/drm/msm/msm_drv.c
View file

@ -912,14 +912,9 @@ static int msm_ioctl_gem_madvise(struct drm_device *dev, void *data,
return -EINVAL;
}
ret = mutex_lock_interruptible(&dev->struct_mutex);
if (ret)
return ret;
obj = drm_gem_object_lookup(file, args->handle);
if (!obj) {
ret = -ENOENT;
goto unlock;
return -ENOENT;
}
ret = msm_gem_madvise(obj, args->madv);
@ -928,10 +923,8 @@ static int msm_ioctl_gem_madvise(struct drm_device *dev, void *data,
ret = 0;
}
drm_gem_object_put_locked(obj);
drm_gem_object_put(obj);
unlock:
mutex_unlock(&dev->struct_mutex);
return ret;
}

4
drivers/gpu/drm/msm/msm_gem.c
View file

@ -672,8 +672,6 @@ int msm_gem_madvise(struct drm_gem_object *obj, unsigned madv)
msm_gem_lock(obj);
WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex));
if (msm_obj->madv != __MSM_MADV_PURGED)
msm_obj->madv = madv;
@ -690,7 +688,6 @@ void msm_gem_purge(struct drm_gem_object *obj)
struct msm_gem_object *msm_obj = to_msm_bo(obj);
WARN_ON(!mutex_is_locked(&dev->struct_mutex));
WARN_ON(!msm_gem_is_locked(obj));
WARN_ON(!is_purgeable(msm_obj));
WARN_ON(obj->import_attach);
@ -770,6 +767,7 @@ void msm_gem_active_get(struct drm_gem_object *obj, struct msm_gpu *gpu)
struct msm_drm_private *priv = obj->dev->dev_private;
might_sleep();
WARN_ON(!msm_gem_is_locked(obj));
WARN_ON(msm_obj->madv != MSM_MADV_WILLNEED);
if (!atomic_fetch_inc(&msm_obj->active_count)) {

2
drivers/gpu/drm/msm/msm_gem.h
View file

@ -190,8 +190,6 @@ static inline bool is_active(struct msm_gem_object *msm_obj)
static inline bool is_purgeable(struct msm_gem_object *msm_obj)
{
WARN_ON(!msm_gem_is_locked(&msm_obj->base));
WARN_ON(!mutex_is_locked(&msm_obj->base.dev->struct_mutex));
return (msm_obj->madv == MSM_MADV_DONTNEED) && msm_obj->sgt &&
!msm_obj->base.dma_buf && !msm_obj->base.import_attach;
}