Re: [linux-next:master 2780/3509] lib/zstd/compress/huf_compress.c:460 HUF_getIndex() warn: the 'RANK_POSITION_LOG_BUCKETS_BEGIN' macro might need parens

From: Nick Terrell <terrelln@meta.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "oe-kbuild@lists.linux.dev" <oe-kbuild@lists.linux.dev>,
	kernel test robot <lkp@intel.com>,
	"oe-kbuild-all@lists.linux.dev" <oe-kbuild-all@lists.linux.dev>,
	Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [linux-next:master 2780/3509] lib/zstd/compress/huf_compress.c:460 HUF_getIndex() warn: the 'RANK_POSITION_LOG_BUCKETS_BEGIN' macro might need parens
Date: Thu, 27 Oct 2022 18:01:39 +0000	[thread overview]
Message-ID: <E1803894-535D-462D-9760-01E9A5216A20@fb.com> (raw)
In-Reply-To: <202210262313.LLXfFkhS-lkp@intel.com>

> On Oct 27, 2022, at 12:59 AM, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> 
> !-------------------------------------------------------------------|
>  This Message Is From an External Sender
> 
> |-------------------------------------------------------------------!
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   60eac8672b5b6061ec07499c0f1b79f6d94311ce
> commit: 2aa14b1ab2c41a4fe41efae80d58bb77da91f19f [2780/3509] zstd: import usptream v1.5.2
> config: i386-randconfig-m021
> compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
> 
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> | Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> smatch warnings:
> lib/zstd/compress/huf_compress.c:460 HUF_getIndex() warn: the 'RANK_POSITION_LOG_BUCKETS_BEGIN' macro might need parens
> lib/zstd/compress/huf_compress.c:460 HUF_getIndex() warn: the 'RANK_POSITION_LOG_BUCKETS_BEGIN' macro might need parens
> lib/zstd/decompress/zstd_decompress_internal.h:206 ZSTD_DCtx_get_bmi2() warn: inconsistent indenting
> lib/zstd/decompress/zstd_decompress_block.c:894 ZSTD_execSequenceEnd() warn: inconsistent indenting
> lib/zstd/decompress/zstd_decompress_block.c:942 ZSTD_execSequenceEndSplitLitBuffer() warn: inconsistent indenting
> lib/zstd/decompress/zstd_decompress_block.c:1009 ZSTD_execSequence() warn: inconsistent indenting
> 
> vim +/RANK_POSITION_LOG_BUCKETS_BEGIN +460 lib/zstd/compress/huf_compress.c
> 
> 2aa14b1ab2c41a Nick Terrell 2022-10-17  457  static U32 HUF_getIndex(U32 const count) {
> 2aa14b1ab2c41a Nick Terrell 2022-10-17  458      return (count < RANK_POSITION_DISTINCT_COUNT_CUTOFF)
> 2aa14b1ab2c41a Nick Terrell 2022-10-17  459          ? count
> 2aa14b1ab2c41a Nick Terrell 2022-10-17 @460          : BIT_highbit32(count) + RANK_POSITION_LOG_BUCKETS_BEGIN;
> 
> These sorts of bugs where we're missing a () around a macro are very
> rare in the kernel so it's a real treat to find one.  :)  It's harmless
> in this case because the math works out the same either way.

Nice catch! Filed an issue upstream [0] to fix that. Will backport the fix & add it to the patch series.

Best,
Nick Terrell

[0] https://github.com/facebook/zstd/issues/3301

> 2aa14b1ab2c41a Nick Terrell 2022-10-17  461  }
> 
> -- 
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