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

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Message-Id: <20190726112821.19775-1-anders.roxell@linaro.org>
Date:   Fri, 26 Jul 2019 13:28:21 +0200
From:   Anders Roxell <anders.roxell@...aro.org>
To:     will@...nel.org, joro@...tes.org
Cc:     linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Anders Roxell <anders.roxell@...aro.org>,
        stable@...r.kernel.org
Subject: [PATCH] iommu: arm-smmu-v3: Mark expected switch fall-through

When fall-through warnings was enabled by default, commit d93512ef0f0e
("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@...r.kernel.org # v4.2+
Fixes: 5bc0a11664e1 ("iommu/arm-smmu: Don't BUG() if we find aborting STEs with disable_bypass")
Signed-off-by: Anders Roxell <anders.roxell@...aro.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();
+			break;
 		default:
 			BUG(); /* STE corruption */
 		}
-- 
2.20.1