2017-07-15 06:04:49

by Jakub Kicinski

Subject: [PATCH net] jhash: fix -Wimplicit-fallthrough warnings

GCC 7 added a new -Wimplicit-fallthrough warning. It's only enabled
with W=1, but since linux/jhash.h is included in over hundred places
(including other global headers) it seems worthwhile fixing this
warning.

Signed-off-by: Jakub Kicinski <[email protected]>
---
If it looks good, would it be OK to take it via the net tree?

include/linux/jhash.h | 29 ++++++++++++++---------------
1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/include/linux/jhash.h b/include/linux/jhash.h
index 348c6f47e4cc..8037850f3104 100644
--- a/include/linux/jhash.h
+++ b/include/linux/jhash.h
@@ -85,19 +85,18 @@ static inline u32 jhash(const void *key, u32 length, u32 initval)
k += 12;
}
/* Last block: affect all 32 bits of (c) */
- /* All the case statements fall through */
switch (length) {
- case 12: c += (u32)k[11]<<24;
- case 11: c += (u32)k[10]<<16;
- case 10: c += (u32)k[9]<<8;
- case 9: c += k[8];
- case 8: b += (u32)k[7]<<24;
- case 7: b += (u32)k[6]<<16;
- case 6: b += (u32)k[5]<<8;
- case 5: b += k[4];
- case 4: a += (u32)k[3]<<24;
- case 3: a += (u32)k[2]<<16;
- case 2: a += (u32)k[1]<<8;
+ case 12: c += (u32)k[11]<<24; /* fall through */
+ case 11: c += (u32)k[10]<<16; /* fall through */
+ case 10: c += (u32)k[9]<<8; /* fall through */
+ case 9: c += k[8]; /* fall through */
+ case 8: b += (u32)k[7]<<24; /* fall through */
+ case 7: b += (u32)k[6]<<16; /* fall through */
+ case 6: b += (u32)k[5]<<8; /* fall through */
+ case 5: b += k[4]; /* fall through */
+ case 4: a += (u32)k[3]<<24; /* fall through */
+ case 3: a += (u32)k[2]<<16; /* fall through */
+ case 2: a += (u32)k[1]<<8; /* fall through */
case 1: a += k[0];
__jhash_final(a, b, c);
case 0: /* Nothing left to add */
@@ -131,10 +130,10 @@ static inline u32 jhash2(const u32 *k, u32 length, u32 initval)
k += 3;
}

- /* Handle the last 3 u32's: all the case statements fall through */
+ /* Handle the last 3 u32's */
switch (length) {
- case 3: c += k[2];
- case 2: b += k[1];
+ case 3: c += k[2]; /* fall through */
+ case 2: b += k[1]; /* fall through */
case 1: a += k[0];
__jhash_final(a, b, c);
case 0: /* Nothing left to add */
--
2.11.0

2017-07-17 16:23:31

by David Miller

Subject: Re: [PATCH net] jhash: fix -Wimplicit-fallthrough warnings

From: Jakub Kicinski <[email protected]>
Date: Fri, 14 Jul 2017 23:03:49 -0700

> GCC 7 added a new -Wimplicit-fallthrough warning. It's only enabled
> with W=1, but since linux/jhash.h is included in over hundred places
> (including other global headers) it seems worthwhile fixing this
> warning.
>
> Signed-off-by: Jakub Kicinski <[email protected]>
> ---
> If it looks good, would it be OK to take it via the net tree?

Applied, thanks Jakub.