* Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> wrote:
> 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@xxxxxxxxxx>
> > >
> > > 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. [...]
Please don't do intentional optimizations while mixing them with a very ugly
coding style:
if ((ctx->partial_block_buffer_length) | (len < SHA256_BLOCK_SIZE)) {
The extra, unnecessary parantheses around ctx->partial_block_buffer_length will
make the ordinary reader assume that the person who wrote the code was unsure
about basic C syntax details and typoed the '|' as well ...
Also, for heaven's (and readability's) sake, pick shorter structure field names.
What's wrong with ctx->partial_block_buf_len?
Also, even if the '|' was intentional - wouldn't it result in better code to use
'||'?
Plus:
> > > /* Compute how many bytes to copy from user buffer into
> > > * extra block
> > > */
please use the customary (multi-line) comment style:
/*
* Comment .....
* ...... goes here.
*/
specified in Documentation/CodingStyle.
Thanks,
Ingo
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