On 8/28/26 11:53, Zhu Lingshan wrote: > This commit introduces a new helper > amdgpu_lookup_queue_by_doorbell which helps > look up a user queue with the given doorbell id > in a xarray. > > This function takes a kref of the user space queue.
Well absolutely clear NAK to the whole approach. This is the nonsense Sunil and I have worked quite hard to remove and we certainly shouldn't repeat such mistakes. When the userq needs to be used from interrupt context we need to hold the xa_lock_irqsave() or otherwise we don't have any guarantee that the userq, userq_mgr or associated fpriv went out of scope. Grabbing references from this side would obviously result in circle dependencies. Regards, Christian. > > Signed-off-by: Zhu Lingshan <[email protected]> > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 30 +++++++++++++++++++++++ > drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h | 2 ++ > 2 files changed, 32 insertions(+) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c > b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c > index 0a816b3c5ff9..e0639f844a8e 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c > @@ -609,6 +609,36 @@ struct amdgpu_usermode_queue *amdgpu_userq_get(struct > amdgpu_userq_mgr *uq_mgr, > return queue; > } > > +/** > + * amdgpu_lookup_queue_by_doorbell - look up a user queue by doorbell > + * @xa: user queue XArray indexed by doorbell > + * @doorbell: doorbell index > + * > + * Return: A queue with the doorbell indexed, or NULL if no such a queue > found. > + * > + * This function increases kref of the queue, the caller > + * must release the reference with amdgpu_userq_put(). > + */ > +struct amdgpu_usermode_queue * > +amdgpu_lookup_queue_by_doorbell(struct xarray *xa, u32 doorbell) > +{ > + struct amdgpu_usermode_queue *queue; > + unsigned long flags; > + > + xa_lock_irqsave(xa, flags); > + queue = xa_load(xa, doorbell); > + if (!queue) > + goto out_unlock; > + > + if (!kref_get_unless_zero(&queue->refcount)) > + queue = NULL; > + > +out_unlock: > + xa_unlock_irqrestore(xa, flags); > + > + return queue; > +} > + > void amdgpu_userq_put(struct amdgpu_usermode_queue *queue) > { > if (queue) > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h > b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h > index 6412a7f7b6ef..8fc73862f64e 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.h > @@ -151,6 +151,8 @@ struct amdgpu_db_info { > }; > > struct amdgpu_usermode_queue *amdgpu_userq_get(struct amdgpu_userq_mgr > *uq_mgr, u32 qid); > +struct amdgpu_usermode_queue * > +amdgpu_lookup_queue_by_doorbell(struct xarray *xa, u32 doorbell); > void amdgpu_userq_put(struct amdgpu_usermode_queue *queue); > > int amdgpu_userq_ioctl(struct drm_device *dev, void *data, struct drm_file > *filp);
