linux-kernel - Re: [RESEND][PATCH v3 14/17] static_call: Add static_cond

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Message-ID: <CAHk-=wiumU4QxAkT+GqhBt5f-iUsoLNC0sqVfRKp0xypA6aNYg@mail.gmail.com>
Date:   Tue, 24 Mar 2020 09:14:03 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "the arch/x86 maintainers" <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Jason Baron <jbaron@...mai.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Nadav Amit <namit@...are.com>,
        Peter Anvin <hpa@...or.com>,
        Andrew Lutomirski <luto@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [RESEND][PATCH v3 14/17] static_call: Add static_cond_call()

On Tue, Mar 24, 2020 at 7:25 AM Peter Zijlstra <peterz@...radead.org> wrote:
>
> Extend the static_call infrastructure to optimize the following common
> pattern:
>
>         if (func_ptr)
>                 func_ptr(args...)

Is there any reason why this shouldn't be the default static call pattern?

IOW, do we need the special "cond" versions at all? Couldn't we just
say that this is how static calls fundamentally work - if the function
is NULL, they are nops?

               Linus