On 26/07/2019 12:28, Anders Roxell wrote:

When fall-through warnings was enabled by default, commit d93512ef0f0e

That commit ID only exists in a handful of old linux-next tags.

("Makefile: Globally enable fall-through warning"), the following warning was starting to show up:

../drivers/iommu/arm-smmu-v3.c: In function ‘arm_smmu_write_strtab_ent’: ../drivers/iommu/arm-smmu-v3.c:1189:7: warning: this statement may fall through [-Wimplicit-fallthrough=] if (disable_bypass) ^ ../drivers/iommu/arm-smmu-v3.c:1191:3: note: here default: ^~~~~~~

Rework so that the compiler doesn't warn about fall-through. Make it clearer by calling 'BUG()' when disable_bypass is set, and always 'break;'

Cc: stable@vger.kernel.org # v4.2+ Fixes: 5bc0a11664e1 ("iommu/arm-smmu: Don't BUG() if we find aborting STEs with disable_bypass")

Why? There's no actual bug, and not even current kernels have that warning enabled.

Signed-off-by: Anders Roxell anders.roxell@linaro.org

drivers/iommu/arm-smmu-v3.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index a9a9fabd3968..8e5f0565996d 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -1186,8 +1186,9 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid, ste_live = true; break; case STRTAB_STE_0_CFG_ABORT:

• 	if (disable_bypass)
  

• 		break;
  

• 	if (!disable_bypass)
  

• 		BUG();
  

You may as well just use BUG_ON().

Robin.

• 	break;
  

  default: BUG(); /* STE corruption */ }