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

From: kernel test robot
Date: Mon Jun 03 2024 - 02:38:28 EST


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: c3f38fa61af77b49866b006939479069cd451173
commit: 9257959a6e5b4fca6fc8e985790bff62c2046f20 locking/atomic: scripts: restructure fallback ifdeffery
date: 12 months ago
config: arc-randconfig-r022-20230104 (https://download.01.org/0day-ci/archive/20240603/202406031408.wNSVlKLV-lkp@xxxxxxxxx/config)
compiler: arc-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240603/202406031408.wNSVlKLV-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/202406031408.wNSVlKLV-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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https://github.com/intel/lkp-tests/wiki