On 10/20/26 09:14, Philipp Stanner wrote:

On Tue, 2026-07-21 at 09:21 +0100, André Draszik wrote:

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v3:

• Philipp: update kerneldoc, add Fixes:

v2: new patch

drivers/gpu/drm/drm_crtc.c | 15 ++++++++++++---  1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 63ead8ba6756..e8e80c936852 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -493,14 +493,23 @@ EXPORT_SYMBOL(__drmm_crtc_alloc_with_planes);   * drm_crtc_cleanup - Clean up the core crtc usage   * @crtc: CRTC to cleanup   *

• • This function cleans up @crtc and removes it from the DRM mode setting
• • core. Note that the function does *not* free the crtc structure itself,
• • this is the responsibility of the caller.

• • This function cleans up @crtc and removes it from the DRM mode setting core,
• • after first waiting an RCU grace period to ensure @crtc->dev can safely be
• • dereferenced by our dma_fence_ops.
• • Note that the function does *not* free the crtc structure itself, this is the
• • responsibility of the caller.

*/  void drm_crtc_cleanup(struct drm_crtc *crtc)  {   struct drm_device *dev = crtc->dev;

• /* Ensure our dma_fence_ops remain valid for an RCU grace period after

• * the fence is signaled. This is necessary because our dma_fence_ops
  

• * dereference crtc->dev.
  

• */
  

• synchronize_rcu();

/* Note that the crtc_list is considered to be static; should we   * remove the drm_crtc at runtime we would have to decrement all   * the indices on the drm_crtc after us in the crtc_list.

Seems we forgot [1] this patch. Sorry about that.

This fix also looks fine to me (for now) since it's what the dma_fence contract currently demands.

I'm a bit nervous about a synchronize_rcu() being in every cleanup path, but I suspect it's the most reasonable thing to do now.

Let's wait a day or two to see if anyone has fundamental objections. Could someone with some CRTC knowledge give it an R-b? Otherwise I'd push it this week.

I just picked them up and I'm about to push them to drm-misc-fixes.

Regards, Christian.

Regards, Philipp

[1] https://lore.kernel.org/dri-devel/73fc12734386c9bebc9cf6d3cea4c5f8e125255e.c...