drivers/iommu/io-pgtable-arm.c:330:13: error: void value not ignored as it ought to be

[kernel test robot]

Hi Mark,

FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   10a6e5feccb877c3c75ad11d27942ad52c24815f
commit: 9257959a6e5b4fca6fc8e985790bff62c2046f20 locking/atomic: scripts: restructure fallback ifdeffery
date:   4 months ago
config: arc-allyesconfig (https://download.01.org/0day-ci/archive/20231014/202310140346.CeDibeBG-lkp@xxxxxxxxx/config)
compiler: arceb-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231014/202310140346.CeDibeBG-lkp@xxxxxxxxx/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@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310140346.CeDibeBG-lkp@xxxxxxxxx/

All errors (new ones prefixed by >>):

   drivers/iommu/io-pgtable-arm.c: In function 'arm_lpae_install_table':
>> drivers/iommu/io-pgtable-arm.c:330:13: error: void value not ignored as it ought to be
     330 |         old = cmpxchg64_relaxed(ptep, curr, new);
         |             ^
--
   drivers/iommu/io-pgtable-dart.c: In function 'dart_install_table':
>> drivers/iommu/io-pgtable-dart.c:168:13: error: void value not ignored as it ought to be
     168 |         old = cmpxchg64_relaxed(ptep, curr, new);
         |             ^
   drivers/iommu/io-pgtable-dart.c:157:25: warning: variable 'new' set but not used [-Wunused-but-set-variable]
     157 |         dart_iopte old, new;
         |                         ^~~


vim +330 drivers/iommu/io-pgtable-arm.c

c896c132b01895 Laurent Pinchart   2014-12-14  310  
fb3a95795da53d Robin Murphy       2017-06-22  311  static arm_lpae_iopte arm_lpae_install_table(arm_lpae_iopte *table,
fb3a95795da53d Robin Murphy       2017-06-22  312  					     arm_lpae_iopte *ptep,
2c3d273eabe8b1 Robin Murphy       2017-06-22  313  					     arm_lpae_iopte curr,
9abe2ac834851a Hector Martin      2021-11-20  314  					     struct arm_lpae_io_pgtable *data)
fb3a95795da53d Robin Murphy       2017-06-22  315  {
2c3d273eabe8b1 Robin Murphy       2017-06-22  316  	arm_lpae_iopte old, new;
9abe2ac834851a Hector Martin      2021-11-20  317  	struct io_pgtable_cfg *cfg = &data->iop.cfg;
e1d3c0fd701df8 Will Deacon        2014-11-14  318  
9abe2ac834851a Hector Martin      2021-11-20  319  	new = paddr_to_iopte(__pa(table), data) | ARM_LPAE_PTE_TYPE_TABLE;
fb3a95795da53d Robin Murphy       2017-06-22  320  	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS)
fb3a95795da53d Robin Murphy       2017-06-22  321  		new |= ARM_LPAE_PTE_NSTABLE;
e1d3c0fd701df8 Will Deacon        2014-11-14  322  
77f3445866c39d Will Deacon        2017-06-23  323  	/*
77f3445866c39d Will Deacon        2017-06-23  324  	 * Ensure the table itself is visible before its PTE can be.
77f3445866c39d Will Deacon        2017-06-23  325  	 * Whilst we could get away with cmpxchg64_release below, this
77f3445866c39d Will Deacon        2017-06-23  326  	 * doesn't have any ordering semantics when !CONFIG_SMP.
77f3445866c39d Will Deacon        2017-06-23  327  	 */
77f3445866c39d Will Deacon        2017-06-23  328  	dma_wmb();
2c3d273eabe8b1 Robin Murphy       2017-06-22  329  
2c3d273eabe8b1 Robin Murphy       2017-06-22 @330  	old = cmpxchg64_relaxed(ptep, curr, new);
2c3d273eabe8b1 Robin Murphy       2017-06-22  331  
4f41845b340783 Will Deacon        2019-06-25  332  	if (cfg->coherent_walk || (old & ARM_LPAE_PTE_SW_SYNC))
2c3d273eabe8b1 Robin Murphy       2017-06-22  333  		return old;
2c3d273eabe8b1 Robin Murphy       2017-06-22  334  
2c3d273eabe8b1 Robin Murphy       2017-06-22  335  	/* Even if it's not ours, there's no point waiting; just kick it */
41e1eb2546e9c8 Isaac J. Manjarres 2021-06-16  336  	__arm_lpae_sync_pte(ptep, 1, cfg);
2c3d273eabe8b1 Robin Murphy       2017-06-22  337  	if (old == curr)
2c3d273eabe8b1 Robin Murphy       2017-06-22  338  		WRITE_ONCE(*ptep, new | ARM_LPAE_PTE_SW_SYNC);
2c3d273eabe8b1 Robin Murphy       2017-06-22  339  
2c3d273eabe8b1 Robin Murphy       2017-06-22  340  	return old;
e1d3c0fd701df8 Will Deacon        2014-11-14  341  }
e1d3c0fd701df8 Will Deacon        2014-11-14  342  

:::::: The code at line 330 was first introduced by commit
:::::: 2c3d273eabe8b1ed3b3cffe2c79643b1bf7e2d4a iommu/io-pgtable-arm: Support lockless operation

:::::: TO: Robin Murphy <robin.murphy@xxxxxxx>
:::::: CC: Will Deacon <will.deacon@xxxxxxx>

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