From: Joe Perches <joe@perches.com>
To: Mathieu Malaterre <malat@debian.org>,
"Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] lib/siphash.c: annotate implicit fall throughs
Date: Wed, 13 Mar 2019 18:50:57 -0700 [thread overview]
Message-ID: <f7497e7ee0365364e8215d8ee3436812f75096c4.camel@perches.com> (raw)
In-Reply-To: <20190313211230.17527-1-malat@debian.org>
On Wed, 2019-03-13 at 22:12 +0100, Mathieu Malaterre wrote:
> There is a plan to build the kernel with -Wimplicit-fallthrough and
> these places in the code produced warnings (W=1). Fix them up.
>
> This commit remove the following warnings:
>
> lib/siphash.c:71:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
> lib/siphash.c:72:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
> lib/siphash.c:73:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
> lib/siphash.c:75:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
> lib/siphash.c:108:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
> lib/siphash.c:109:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
> lib/siphash.c:110:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
> lib/siphash.c:112:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
> lib/siphash.c:434:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
> lib/siphash.c:462:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>
> Move the break statement onto the next line to match the fall-through
> comment pattern. Also move the trailing statement onto the next line to
> pass checkpatch verification.
[]
> diff --git a/lib/siphash.c b/lib/siphash.c
[].
> @@ -68,13 +68,26 @@ u64 __siphash_aligned(const void *data, size_t len, const siphash_key_t *key)
> bytemask_from_count(left)));
> #else
> switch (left) {
> - case 7: b |= ((u64)end[6]) << 48;
> - case 6: b |= ((u64)end[5]) << 40;
> - case 5: b |= ((u64)end[4]) << 32;
It might also be worth not casting to u64 then shift
as that can be
moderately expensive on 32 bit systems
and instead use ((char
*)&b)[<appropriate_index>].
> - case 4: b |= le32_to_cpup(data); break;
> - case 3: b |= ((u64)end[2]) << 16;
Perhaps an unnecessary cast before shift
> - case 2: b |= le16_to_cpup(data); break;
> - case 1: b |= end[0];
[]
> @@ -101,13 +114,26 @@ u64 __siphash_unaligned(const void *data, size_t len, const siphash_key_t *key)
> bytemask_from_count(left)));
> #else
> switch (left) {
> - case 7: b |= ((u64)end[6]) << 48;
> - case 6: b |= ((u64)end[5]) << 40;
> - case 5: b |= ((u64)end[4]) << 32;
etc...
> - case 4: b |= get_unaligned_le32(end); break;
> - case 3: b |= ((u64)end[2]) << 16;
> - case 2: b |= get_unaligned_le16(end); break;
> - case 1: b |= end[0];
next prev parent reply other threads:[~2019-03-14 1:54 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-14 20:19 [PATCH] lib/siphash.c:: annotate implicit fall throughs Mathieu Malaterre
2019-01-14 21:04 ` Gustavo A. R. Silva
2019-03-13 20:24 ` [PATCH v2] lib/siphash.c: " Mathieu Malaterre
2019-03-13 20:34 ` Jason A. Donenfeld
2019-03-13 20:44 ` Gustavo A. R. Silva
2019-03-13 20:52 ` Mathieu Malaterre
2019-03-13 21:12 ` [PATCH v3] " Mathieu Malaterre
2019-03-14 1:50 ` Joe Perches [this message]
2019-03-14 7:01 ` Jason A. Donenfeld
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