From: Ingo Molnar Date: Fri, 01 Jul 2016 07:55:59 +0000 Subject: Re: [patch] crypto: sha256-mb - cleanup a || vs | typo Message-Id: <20160701075559.GA11902@gmail.com> List-Id: References: <20160629144242.GE22818@mwanda> <8538242a-eab7-127e-e47e-26027fee4f6d@zytor.com> <1467319339.22178.256.camel@linux.intel.com> In-Reply-To: <1467319339.22178.256.camel@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Tim Chen Cc: "H. Peter Anvin" , Dan Carpenter , Herbert Xu , "David S. Miller" , Thomas Gleixner , Ingo Molnar , x86@kernel.org, Megha Dey , "Wang, Rui Y" , Denys Vlasenko , Xiaodong Liu , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org * Tim Chen wrote: > On Wed, 2016-06-29 at 10:05 -0700, H. Peter Anvin wrote: > > On 06/29/16 07:42, Dan Carpenter wrote: > > >=20 > > > >=20 > > > > >=20 > > > > > and | behave basically the same here but || is intended.=A0=A0It = causes a > > > static checker warning to mix up bitwise and logical operations. > > >=20 > > > Signed-off-by: Dan Carpenter > > >=20 > > > diff --git a/arch/x86/crypto/sha256-mb/sha256_mb.c b/arch/x86/crypto/= sha256-mb/sha256_mb.c > > > index c9d5dcc..4ec895a 100644 > > > --- a/arch/x86/crypto/sha256-mb/sha256_mb.c > > > +++ b/arch/x86/crypto/sha256-mb/sha256_mb.c > > > @@ -299,7 +299,7 @@ static struct sha256_hash_ctx *sha256_ctx_mgr_sub= mit(struct sha256_ctx_mgr *mgr, > > > =A0 =A0* Or if the user's buffer contains less than a whole block, > > > =A0 =A0* append as much as possible to the extra block. > > > =A0 =A0*/ > > > - if ((ctx->partial_block_buffer_length) | (len < SHA256_BLOCK_SIZE))= { > > > + if ((ctx->partial_block_buffer_length) || (len < SHA256_BLOCK_SIZE)= ) { > > > =A0 /* Compute how many bytes to copy from user buffer into > > > =A0 =A0* extra block > > > =A0 =A0*/ > > >=20 > > As far as I know the | was an intentional optimization, so you may way > > to look at the generated code. > >=20 > > -hpa > >=20 >=20 > Yes, this is an intentional optimization. [...] Please don't do intentional optimizations while mixing them with a very ugl= y=20 coding style: if ((ctx->partial_block_buffer_length) | (len < SHA256_BLOCK_SIZE)) { The extra, unnecessary parantheses around ctx->partial_block_buffer_length = will=20 make the ordinary reader assume that the person who wrote the code was unsu= re=20 about basic C syntax details and typoed the '|' as well ... Also, for heaven's (and readability's) sake, pick shorter structure field n= ames.=20 What's wrong with ctx->partial_block_buf_len? Also, even if the '|' was intentional - wouldn't it result in better code t= o use=20 '||'? Plus: > > > =A0 /* Compute how many bytes to copy from user buffer into > > > =A0 =A0* extra block > > > =A0 =A0*/ please use the customary (multi-line) comment style: /* * Comment ..... * ...... goes here. */ specified in Documentation/CodingStyle. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html