From: Lukas Wunner <lukas@wunner.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: David Howells <dhowells@redhat.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ard Biesheuvel <ardb@kernel.org>,
Jarkko Sakkinen <jarkko@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Nathan Chancellor <nathan@kernel.org>
Subject: Re: [PATCH v2] X.509: Introduce scope-based x509_certificate allocation
Date: Tue, 13 Feb 2024 06:04:45 +0100 [thread overview]
Message-ID: <20240213050445.GA27995@wunner.de> (raw)
In-Reply-To: <65ca861e14779_5a7f2949e@dwillia2-xfh.jf.intel.com.notmuch>
On Mon, Feb 12, 2024 at 12:57:02PM -0800, Dan Williams wrote:
> Lukas Wunner wrote:
> > On Mon, Feb 12, 2024 at 11:07:06AM -0800, Dan Williams wrote:
> > > Lukas Wunner wrote:
> > > > In x509_cert_parse(), add a hint for the compiler that kzalloc()
> > > > never returns an ERR_PTR(). Otherwise the compiler adds a gratuitous
> > > > IS_ERR() check on return. Introduce a handy assume() macro for this
> > > > which can be re-used elsewhere in the kernel to provide hints for the
> > > > compiler.
>
> Might I suggest the following:
>
> > diff --git a/include/linux/compiler.h b/include/linux/compiler.h
> > index bb1339c..384803e 100644
> > --- a/include/linux/compiler.h
> > +++ b/include/linux/compiler.h
> > @@ -139,6 +139,8 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
> > } while (0)
> > #endif
> >
> > +#define assume(cond) do if(!(cond)) __builtin_unreachable(); while(0)
>
> s/__builtin_unreachable()/unreachable()/?
I tried that and it didn't work. The superfluous IS_ERR() check
was not optimized away by gcc. It seemed to remove the unreachable
portion of the code before using it for optimization of the code.
> Move this to cleanup.h and add extend the DEFINE_FREE() comment about
> its usage:
Yes, spreading the knowledge in this way might make sense.
I'll wait for Peter to weigh in before submitting that though.
Thanks,
Lukas
prev parent reply other threads:[~2024-02-13 5:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-12 11:24 [PATCH v2] X.509: Introduce scope-based x509_certificate allocation Lukas Wunner
2024-02-12 12:19 ` Andy Shevchenko
2024-02-12 16:36 ` Lukas Wunner
2024-02-12 18:10 ` Jarkko Sakkinen
2024-02-12 19:07 ` Dan Williams
2024-02-12 19:20 ` Lukas Wunner
2024-02-12 20:57 ` Dan Williams
2024-02-13 5:04 ` Lukas Wunner [this message]
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