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drm: nest modeset locks within fpriv->fbs_lock

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Atm we still need to unconditionally take the modeset locks in the
rmfb paths. But eventually we only want to take them if there are
other users around as a slow-path. This way sane userspace avoids
blocking on edid reads and other stuff in rmfb if it ensures that the
fb isn't used anywhere by a crtc/plane.

We can do a quick check for such other users once framebuffers are
properly refcounting by locking at the refcount - if it's more than 1,
there are other users left. Again, rmfb racing against other ioctls
isn't a real problem, userspace is allowed to shoot its foot.

This patch just prepares this by moving the modeset locks to nest
within fpriv->fbs_lock. Now the distinction between the fbs_lock and
the device-global fb_lock is clear, since we need to hold the fbs_lock
outside of any modeset_locks in fb_release.

Reviewed-by: Rob Clark <rob@ti.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Vetter 2012-12-10 23:44:22 +01:00
parent 2b677e8c08
commit 7d331595b0
1 changed files with 4 additions and 4 deletions
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8
drivers/gpu/drm/drm_crtc.c
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@ -2282,13 +2282,13 @@ int drm_mode_addfb(struct drm_device *dev,
drm_modeset_unlock_all(dev);
return PTR_ERR(fb);
}
drm_modeset_unlock_all(dev);
mutex_lock(&file_priv->fbs_lock);
or->fb_id = fb->base.id;
list_add(&fb->filp_head, &file_priv->fbs);
DRM_DEBUG_KMS("[FB:%d]\n", fb->base.id);
mutex_unlock(&file_priv->fbs_lock);
drm_modeset_unlock_all(dev);
return ret;
}
@ -2465,6 +2465,7 @@ int drm_mode_addfb2(struct drm_device *dev,
drm_modeset_unlock_all(dev);
return PTR_ERR(fb);
}
drm_modeset_unlock_all(dev);
mutex_lock(&file_priv->fbs_lock);
r->fb_id = fb->base.id;
@ -2472,7 +2473,6 @@ int drm_mode_addfb2(struct drm_device *dev,
DRM_DEBUG_KMS("[FB:%d]\n", fb->base.id);
mutex_unlock(&file_priv->fbs_lock);
drm_modeset_unlock_all(dev);
return ret;
}
@ -2670,7 +2670,6 @@ void drm_fb_release(struct drm_file *priv)
struct drm_device *dev = priv->minor->dev;
struct drm_framebuffer *fb, *tfb;
drm_modeset_lock_all(dev);
mutex_lock(&priv->fbs_lock);
list_for_each_entry_safe(fb, tfb, &priv->fbs, filp_head) {
@ -2682,10 +2681,11 @@ void drm_fb_release(struct drm_file *priv)
list_del_init(&fb->filp_head);
/* This will also drop the fpriv->fbs reference. */
drm_modeset_lock_all(dev);
drm_framebuffer_remove(fb);
drm_modeset_unlock_all(dev);
}
mutex_unlock(&priv->fbs_lock);
drm_modeset_unlock_all(dev);
}
/**