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From: Andy Lutomirski <luto@amacapital.net>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Jason Baron <jbaron@akamai.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>, Nadav Amit <namit@vmware.com>,
	Peter Anvin <hpa@zytor.com>, Andrew Lutomirski <luto@kernel.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [RESEND][PATCH v3 14/17] static_call: Add static_cond_call()
Date: Tue, 24 Mar 2020 09:22:29 -0700	[thread overview]
Message-ID: <86D80EA7-9087-4042-8119-12DD5FCEAA87@amacapital.net> (raw)
In-Reply-To: <CAHk-=wiumU4QxAkT+GqhBt5f-iUsoLNC0sqVfRKp0xypA6aNYg@mail.gmail.com>


> On Mar 24, 2020, at 9:14 AM, Linus Torvalds <torvalds@linux-foundation.org> wrote:
> 
> On Tue, Mar 24, 2020 at 7:25 AM Peter Zijlstra <peterz@infradead.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?
> 
> 

I haven’t checked if static calls currently support return values, but the conditional case only makes sense for functions that return void. 

Aside from that, it might be nice for passing NULL in to warn or bug when the NULL pointer is stored instead of silently NOPping out the call in cases where having a real implementation isn’t optional.

  reply	other threads:[~2020-03-24 16:22 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24 13:56 [RESEND][PATCH v3 00/17] Add static_call() Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 01/17] notifier: Fix broken error handling pattern Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 02/17] module: Fix up module_notifier return values Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 03/17] module: Properly propagate MODULE_STATE_COMING failure Peter Zijlstra
2020-03-25 17:35   ` Jessica Yu
2020-03-27  4:51     ` Josh Poimboeuf
2020-03-27 12:04     ` Miroslav Benes
2020-03-24 13:56 ` [RESEND][PATCH v3 04/17] jump_label,module: Fix module lifetime for __jump_label_mod_text_reserved Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 05/17] compiler.h: Make __ADDRESSABLE() symbol truly unique Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 06/17] static_call: Add basic static call infrastructure Peter Zijlstra
2020-03-26 16:42   ` Nadav Amit
2020-03-26 17:01     ` Peter Zijlstra
2020-03-26 18:09       ` Nadav Amit
2020-03-26 18:28         ` Peter Zijlstra
2020-03-26 19:02           ` Nadav Amit
2020-03-26 19:13             ` Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 07/17] static_call: Add inline " Peter Zijlstra
2020-03-26 15:54   ` Borislav Petkov
2020-03-24 13:56 ` [RESEND][PATCH v3 08/17] static_call: Avoid kprobes on inline static_call()s Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 09/17] x86/static_call: Add out-of-line static call implementation Peter Zijlstra
2020-03-26 14:57   ` Borislav Petkov
2020-04-06  1:08   ` Fangrui Song
2020-04-06 11:04     ` Peter Zijlstra
2020-04-06 18:29       ` Nick Desaulniers
2020-03-24 13:56 ` [RESEND][PATCH v3 10/17] x86/static_call: Add inline static call implementation for x86-64 Peter Zijlstra
2020-03-26 15:17   ` Borislav Petkov
2020-03-26 16:06   ` Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 11/17] static_call: Simple self-test Peter Zijlstra
2020-03-26 15:44   ` Borislav Petkov
2020-03-26 17:08     ` Peter Zijlstra
2020-03-26 17:33       ` Borislav Petkov
2020-03-24 13:56 ` [RESEND][PATCH v3 12/17] tracepoint: Optimize using static_call() Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 13/17] x86/alternatives: Teach text_poke_bp() to emulate RET Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 14/17] static_call: Add static_cond_call() Peter Zijlstra
2020-03-24 16:14   ` Linus Torvalds
2020-03-24 16:22     ` Andy Lutomirski [this message]
2020-03-24 16:33       ` Linus Torvalds
2020-03-24 17:03         ` Peter Zijlstra
2020-03-25 18:13           ` Peter Zijlstra
2020-03-25 18:26             ` Linus Torvalds
2020-03-25 19:34         ` hpa
2020-03-25 20:52           ` Linus Torvalds
2020-03-25 22:07             ` Peter Zijlstra
2020-03-24 16:54     ` Peter Zijlstra
2020-03-26 23:37   ` Rasmus Villemoes
2020-03-27 10:08     ` Peter Zijlstra
2020-03-27 13:25       ` Rasmus Villemoes
2020-03-24 13:56 ` [RESEND][PATCH v3 15/17] static_call: Handle tail-calls Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 16/17] static_call: Allow early init Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 17/17] x86/perf, static_call: Optimize x86_pmu methods Peter Zijlstra
2020-03-25 17:49 ` [RESEND][PATCH v3 00/17] Add static_call() Peter Zijlstra

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