From: Tim Chen <tim.c.chen@linux.intel.com>
To: "H. Peter Anvin" <hpa@zytor.com>,
Dan Carpenter <dan.carpenter@oracle.com>,
Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, Megha Dey <megha.dey@intel.com>,
"Wang, Rui Y" <rui.y.wang@intel.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Xiaodong Liu <xiaodong.liu@intel.com>,
linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-janitors@vger.kernel.org
Subject: Re: [patch] crypto: sha256-mb - cleanup a || vs | typo
Date: Thu, 30 Jun 2016 20:42:19 +0000 [thread overview]
Message-ID: <1467319339.22178.256.camel@linux.intel.com> (raw)
In-Reply-To: <8538242a-eab7-127e-e47e-26027fee4f6d@zytor.com>
On Wed, 2016-06-29 at 10:05 -0700, H. Peter Anvin wrote:
> On 06/29/16 07:42, Dan Carpenter wrote:
> >
> > >
> > > >
> > > > and | behave basically the same here but || is intended. It causes a
> > static checker warning to mix up bitwise and logical operations.
> >
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> >
> > 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_submit(struct sha256_ctx_mgr *mgr,
> > * Or if the user's buffer contains less than a whole block,
> > * append as much as possible to the extra block.
> > */
> > - if ((ctx->partial_block_buffer_length) | (len < SHA256_BLOCK_SIZE)) {
> > + if ((ctx->partial_block_buffer_length) || (len < SHA256_BLOCK_SIZE)) {
> > /* Compute how many bytes to copy from user buffer into
> > * extra block
> > */
> >
> As far as I know the | was an intentional optimization, so you may way
> to look at the generated code.
>
> -hpa
>
Yes, this is an intentional optimization. Is there any scenario where things may
break with the compiler?
Tim
WARNING: multiple messages have this Message-ID (diff)
From: Tim Chen <tim.c.chen@linux.intel.com>
To: "H. Peter Anvin" <hpa@zytor.com>,
Dan Carpenter <dan.carpenter@oracle.com>,
Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, Megha Dey <megha.dey@intel.com>,
"Wang, Rui Y" <rui.y.wang@intel.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Xiaodong Liu <xiaodong.liu@intel.com>,
linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-janitors@vger.kernel.org
Subject: Re: [patch] crypto: sha256-mb - cleanup a || vs | typo
Date: Thu, 30 Jun 2016 13:42:19 -0700 [thread overview]
Message-ID: <1467319339.22178.256.camel@linux.intel.com> (raw)
In-Reply-To: <8538242a-eab7-127e-e47e-26027fee4f6d@zytor.com>
On Wed, 2016-06-29 at 10:05 -0700, H. Peter Anvin wrote:
> On 06/29/16 07:42, Dan Carpenter wrote:
> >
> > >
> > > >
> > > > and | behave basically the same here but || is intended. It causes a
> > static checker warning to mix up bitwise and logical operations.
> >
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> >
> > 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_submit(struct sha256_ctx_mgr *mgr,
> > * Or if the user's buffer contains less than a whole block,
> > * append as much as possible to the extra block.
> > */
> > - if ((ctx->partial_block_buffer_length) | (len < SHA256_BLOCK_SIZE)) {
> > + if ((ctx->partial_block_buffer_length) || (len < SHA256_BLOCK_SIZE)) {
> > /* Compute how many bytes to copy from user buffer into
> > * extra block
> > */
> >
> As far as I know the | was an intentional optimization, so you may way
> to look at the generated code.
>
> -hpa
>
Yes, this is an intentional optimization. Is there any scenario where things may
break with the compiler?
Tim
next prev parent reply other threads:[~2016-06-30 20:42 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-29 14:42 [patch] crypto: sha256-mb - cleanup a || vs | typo Dan Carpenter
2016-06-29 14:42 ` Dan Carpenter
2016-06-29 17:05 ` H. Peter Anvin
2016-06-29 17:05 ` H. Peter Anvin
2016-06-30 7:50 ` Dan Carpenter
2016-06-30 7:50 ` Dan Carpenter
2016-06-30 11:16 ` Joe Perches
2016-06-30 11:16 ` Joe Perches
2016-06-30 11:45 ` walter harms
2016-06-30 11:45 ` walter harms
2016-06-30 12:33 ` Dan Carpenter
2016-06-30 12:33 ` Dan Carpenter
2016-06-30 20:42 ` Tim Chen [this message]
2016-06-30 20:42 ` Tim Chen
2016-06-30 22:16 ` Dan Carpenter
2016-06-30 22:16 ` Dan Carpenter
2016-07-01 7:55 ` Ingo Molnar
2016-07-01 7:55 ` Ingo Molnar
2016-07-01 9:28 ` Herbert Xu
2016-07-01 9:28 ` Herbert Xu
2016-07-01 10:13 ` Ingo Molnar
2016-07-01 10:13 ` Ingo Molnar
2016-07-08 16:28 ` Tim Chen
2016-07-08 16:28 ` Tim Chen
2016-07-08 16:45 ` Herbert Xu
2016-07-08 16:45 ` Herbert Xu
2016-07-08 17:17 ` Tim Chen
2016-07-08 17:17 ` Tim Chen
2016-07-08 17:19 ` Linus Torvalds
2016-07-08 17:19 ` Linus Torvalds
2016-07-11 6:40 ` Geert Uytterhoeven
2016-07-11 6:40 ` Geert Uytterhoeven
2016-07-18 8:59 ` Pavel Machek
2016-07-18 8:59 ` Pavel Machek
2016-07-18 22:12 ` Tim Chen
2016-07-18 22:12 ` Tim Chen
2016-07-18 22:12 ` Tim Chen
2016-07-11 10:09 ` Herbert Xu
2016-07-11 10:09 ` Herbert Xu
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