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: [email protected] # v3.16
Fixes: 6ee33c2712fc ("ARM: hw_breakpoint: correct and simplify alignment fixup code")
Signed-off-by: Anders Roxell <[email protected]>
---
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;
--
2.20.1
On Fri, Jul 26, 2019 at 01:27:32PM +0200, Anders Roxell wrote:
> 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: [email protected] # v3.16
> Fixes: 6ee33c2712fc ("ARM: hw_breakpoint: correct and simplify alignment fixup code")
> Signed-off-by: Anders Roxell <[email protected]>
> ---
> 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:
Why are you moving the 'case 1:' here? AFAICT, your patch now rejects
byte-aligned watchpoints of length 2.
Will