[bvanassche:thread-safety 89/133] net/core/devmem.c:77:2: warning: ignoring return value of function declared with 'warn_unused_result' attribute

[bvanassche:thread-safety 89/133] net/core/devmem.c:77:2: warning: ignoring return value of function declared with 'warn_unused_result' attribute

[kernel test robot]

tree:   https://github.com/bvanassche/linux thread-safety
head:   09aab91c2fcb166bfe35c0f9c2c5b6b960722087
commit: 138228c4404c30f42ca28639aeab8f8a1f92d07a [89/133] dma-resv: Make checking the dma_resv_lock() return value mandatory
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20261026/202610261208.1M0H73SK-lkp@intel.com/config)
compiler: clang version 22.1.8 (https://github.com/llvm/llvm-project ca7933e47d3a3451d81e72ac174dcb5aa28b59d1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261026/202610261208.1M0H73SK-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/202610261208.1M0H73SK-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> net/core/devmem.c:77:2: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
      77 |         dma_resv_lock(binding->dmabuf->resv, NULL);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/core/devmem.c:246:2: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
     246 |         dma_resv_lock(dmabuf->resv, NULL);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/core/devmem.c:359:2: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
     359 |         dma_resv_lock(dmabuf->resv, NULL);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   3 warnings generated.


vim +/warn_unused_result +77 net/core/devmem.c

5c024716f52bb8b Bobby Eshleman     2026-01-07  66  
bd61848900bff59 Mina Almasry       2025-05-08  67  void __net_devmem_dmabuf_binding_free(struct work_struct *wq)
170aafe35cb98e0 Mina Almasry       2024-09-10  68  {
bd61848900bff59 Mina Almasry       2025-05-08  69  	struct net_devmem_dmabuf_binding *binding = container_of(wq, typeof(*binding), unbind_w);
bd61848900bff59 Mina Almasry       2025-05-08  70  
083e64a3af77173 Stanislav Fomichev 2026-09-17  71  	if (binding->freelist)
13648ba787223c8 Stanislav Fomichev 2026-09-17  72  		WARN(binding->free_count != binding->area.num_niovs,
1cf2f913b3dd934 Stanislav Fomichev 2026-09-25  73  		     "destroying dmabuf binding with outstanding net_iovs: total=%zu, free=%u",
13648ba787223c8 Stanislav Fomichev 2026-09-17  74  		     binding->area.num_niovs, binding->free_count);
170aafe35cb98e0 Mina Almasry       2024-09-10  75  
13648ba787223c8 Stanislav Fomichev 2026-09-17  76  	kvfree(binding->area.niovs);
69ab87acc614cbe Erfan Sharafzadeh  2026-10-13 @77  	dma_resv_lock(binding->dmabuf->resv, NULL);
69ab87acc614cbe Erfan Sharafzadeh  2026-10-13  78  	dma_buf_unmap_attachment(binding->attachment, binding->sgt,
fa516c0d8bf90da Jakub Kicinski     2025-07-31  79  				 binding->direction);
69ab87acc614cbe Erfan Sharafzadeh  2026-10-13  80  	dma_buf_unpin(binding->attachment);
69ab87acc614cbe Erfan Sharafzadeh  2026-10-13  81  	dma_resv_unlock(binding->dmabuf->resv);
170aafe35cb98e0 Mina Almasry       2024-09-10  82  	dma_buf_detach(binding->dmabuf, binding->attachment);
170aafe35cb98e0 Mina Almasry       2024-09-10  83  	dma_buf_put(binding->dmabuf);
170aafe35cb98e0 Mina Almasry       2024-09-10  84  	xa_destroy(&binding->bound_rxqs);
5c024716f52bb8b Bobby Eshleman     2026-01-07  85  	percpu_ref_exit(&binding->ref);
083e64a3af77173 Stanislav Fomichev 2026-09-17  86  	kvfree(binding->freelist);
bd61848900bff59 Mina Almasry       2025-05-08  87  	kvfree(binding->tx_vec);
170aafe35cb98e0 Mina Almasry       2024-09-10  88  	kfree(binding);
170aafe35cb98e0 Mina Almasry       2024-09-10  89  }
170aafe35cb98e0 Mina Almasry       2024-09-10  90  

:::::: The code at line 77 was first introduced by commit
:::::: 69ab87acc614cbe0bd08a65ece6e1aabee805106 net: devmem: allow peer-to-peer dma-buf attach for bindings

:::::: TO: Erfan Sharafzadeh <erfansh@meta.com>
:::::: CC: Jakub Kicinski <kuba@kernel.org>

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