[PATCH v2] iommu: arm-smmu-v3: Mark expected switch fall-through

[Anders Roxell]

Now that -Wimplicit-fallthrough is passed to GCC by default, the
following warning shows 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_ON()' when disable_bypass is set, and always
'break;'

Signed-off-by: Anders Roxell <anders.rox...@linaro.org>
---
 drivers/iommu/arm-smmu-v3.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index a9a9fabd3968..c5c93e48b4db 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -1186,8 +1186,8 @@ 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;
+                       BUG_ON(!disable_bypass);
+                       break;
                default:
                        BUG(); /* STE corruption */
                }
-- 
2.20.1