When fall-through warnings was enabled by default, d93512ef0f0e ("Makefile: Globally enable fall-through warning"), we could see the following warnings was starting to show up. However, this was originally introduced in commit 6ee33c2712fc ("ARM: hw_breakpoint: correct and simplify alignment fixup code"). Commit d968d2b801d8 ("ARM: 7497/1: hw_breakpoint: allow single-byte watchpoints on all addresses") was written with the intent to allow single-byte watchpoints on all addresses but forgot to move 'case 1:' down below 'case 2:'.
../arch/arm/kernel/hw_breakpoint.c: In function ‘hw_breakpoint_arch_parse’: ../arch/arm/kernel/hw_breakpoint.c:609:7: warning: this statement may fall through [-Wimplicit-fallthrough=] if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2) ^ ../arch/arm/kernel/hw_breakpoint.c:611:3: note: here case 3: ^~~~ ../arch/arm/kernel/hw_breakpoint.c:613:7: warning: this statement may fall through [-Wimplicit-fallthrough=] if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1) ^ ../arch/arm/kernel/hw_breakpoint.c:615:3: note: here default: ^~~~~~~
Rework so 'case 1:' are next to 'case 3:' and also add '/* Fall through */' so that the compiler doesn't warn about fall-through.
Cc: stable@vger.kernel.org # v3.16 Fixes: 6ee33c2712fc ("ARM: hw_breakpoint: correct and simplify alignment fixup code") Signed-off-by: Anders Roxell anders.roxell@linaro.org --- arch/arm/kernel/hw_breakpoint.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c index af8b8e15f589..c14d506969ba 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -603,15 +603,17 @@ int hw_breakpoint_arch_parse(struct perf_event *bp, case 0: /* Aligned */ break; - case 1: case 2: /* Allow halfword watchpoints and breakpoints. */ if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2) break; + /* Fall through */ + case 1: case 3: /* Allow single byte watchpoint. */ if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1) break; + /* Fall through */ default: ret = -EINVAL; goto out;