linux-kernel - Re: [PATCH] perf/x86/p4: Fix "Wunused-but-set-variable" warning

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <ZSlsowuVqQA3ecUb@google.com>
Date:   Fri, 13 Oct 2023 09:13:23 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Lucy Mielke <lucymielke@...oud.com>
Cc:     Peter Zijlstra <peterz@...radead.org>, mingo@...hat.com,
        acme@...nel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
        namhyung@...nel.org, irogers@...gle.com, adrian.hunter@...el.com,
        tglx@...utronix.de, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, linux-perf-users@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf/x86/p4: Fix "Wunused-but-set-variable" warning

On Thu, Oct 12, 2023, Lucy Mielke wrote:
> Am Mon, Oct 09, 2023 at 09:29:50AM -0700 schrieb Sean Christopherson:
> > 
> > rdmsr() writes to "high", but nothing ever reads from high.  FWIW, I would _love_
> > for rdmsrl() to have return semantics, e.g. to be able to do:
> > 
> > 	low  = (u32)rdmsrl(MSR_IA32_MISC_ENABLE);
> > 
> > or even
> > 
> > 	if (!(rdmsrl(MSR_IA32_MISC_ENABLE) & BIT(7)))
> 
> I have taken a look and it seems to me like this macro is called quite a lot
> for different things thoughout the kernel tree, including drivers. If
> one were to change it to have return semantics instead of the way it
> currently works, you'd have to change around 300 occurences, right?

Yep, which is the only reason I haven't force the issue.