Re: [PATCH 2/8] dma-buf: detach fence ops on signal v2

[kernel test robot <lkp@intel.com>]

Hi Christian,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm-misc/drm-misc-next]
[cannot apply to drm-i915/for-linux-next drm-i915/for-linux-next-fixes drm-xe/drm-xe-next linus/master v6.19 next-20260220]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Christian-K-nig/dma-buf-detach-fence-ops-on-signal-v2/20260220-010804
base:   https://gitlab.freedesktop.org/drm/misc/kernel.git drm-misc-next
patch link:    https://lore.kernel.org/r/20260219160822.1529-3-christian.koenig%40amd.com
patch subject: [PATCH 2/8] dma-buf: detach fence ops on signal v2
config: hexagon-randconfig-r121-20260221 (https://download.01.org/0day-ci/archive/20260221/202602212322.qKZcoRK3-lkp@intel.com/config)
compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project e86750b29fa0ff207cd43213d66dabe565417638)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260221/202602212322.qKZcoRK3-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202602212322.qKZcoRK3-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
   drivers/dma-buf/dma-fence.c:1051:38: sparse: sparse: incorrect type in initializer (different address spaces) @@     expected char const [noderef] __rcu *timeline @@     got char * @@
   drivers/dma-buf/dma-fence.c:1051:38: sparse:     expected char const [noderef] __rcu *timeline
   drivers/dma-buf/dma-fence.c:1051:38: sparse:     got char *
   drivers/dma-buf/dma-fence.c:1052:36: sparse: sparse: incorrect type in initializer (different address spaces) @@     expected char const [noderef] __rcu *driver @@     got char * @@
   drivers/dma-buf/dma-fence.c:1052:36: sparse:     expected char const [noderef] __rcu *driver
   drivers/dma-buf/dma-fence.c:1052:36: sparse:     got char *
   drivers/dma-buf/dma-fence.c: note: in included file (through include/trace/trace_events.h, include/trace/define_trace.h, include/trace/events/dma_fence.h):
   include/trace/events/dma_fence.h:17:1: sparse: sparse: dereference of noderef expression
   include/trace/events/dma_fence.h:17:1: sparse: sparse: dereference of noderef expression
   include/trace/events/dma_fence.h:17:1: sparse: sparse: dereference of noderef expression
   include/trace/events/dma_fence.h:17:1: sparse: sparse: dereference of noderef expression
   include/trace/events/dma_fence.h:17:1: sparse: sparse: dereference of noderef expression
   include/trace/events/dma_fence.h:17:1: sparse: sparse: dereference of noderef expression
>> drivers/dma-buf/dma-fence.c:379:19: sparse: sparse: dereference of noderef expression
   drivers/dma-buf/dma-fence.c:379:43: sparse: sparse: dereference of noderef expression

vim +379 drivers/dma-buf/dma-fence.c

   345	
   346	
   347	/**
   348	 * dma_fence_signal_timestamp_locked - signal completion of a fence
   349	 * @fence: the fence to signal
   350	 * @timestamp: fence signal timestamp in kernel's CLOCK_MONOTONIC time domain
   351	 *
   352	 * Signal completion for software callbacks on a fence, this will unblock
   353	 * dma_fence_wait() calls and run all the callbacks added with
   354	 * dma_fence_add_callback(). Can be called multiple times, but since a fence
   355	 * can only go from the unsignaled to the signaled state and not back, it will
   356	 * only be effective the first time. Set the timestamp provided as the fence
   357	 * signal timestamp.
   358	 *
   359	 * Unlike dma_fence_signal_timestamp(), this function must be called with
   360	 * &dma_fence.lock held.
   361	 */
   362	void dma_fence_signal_timestamp_locked(struct dma_fence *fence,
   363					      ktime_t timestamp)
   364	{
   365		struct dma_fence_cb *cur, *tmp;
   366		struct list_head cb_list;
   367	
   368		lockdep_assert_held(fence->lock);
   369	
   370		if (unlikely(test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
   371					      &fence->flags)))
   372			return;
   373	
   374		/*
   375		 * When neither a release nor a wait operation is specified set the ops
   376		 * pointer to NULL to allow the fence structure to become independent
   377		 * from who originally issued it.
   378		 */
 > 379		if (!fence->ops->release && !fence->ops->wait)
   380			RCU_INIT_POINTER(fence->ops, NULL);
   381	
   382		/* Stash the cb_list before replacing it with the timestamp */
   383		list_replace(&fence->cb_list, &cb_list);
   384	
   385		fence->timestamp = timestamp;
   386		set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags);
   387		trace_dma_fence_signaled(fence);
   388	
   389		list_for_each_entry_safe(cur, tmp, &cb_list, node) {
   390			INIT_LIST_HEAD(&cur->node);
   391			cur->func(fence, cur);
   392		}
   393	}
   394	EXPORT_SYMBOL(dma_fence_signal_timestamp_locked);
   395	

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