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Date: Mon, 13 May 2024 19:30:49 +0200
From: Michal =?utf-8?Q?Koutn=C3=BD?= <mkoutny@suse.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, 
	Masami Hiramatsu <mhiramat@kernel.org>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, 
	Christian Brauner <brauner@kernel.org>, Oleg Nesterov <oleg@redhat.com>, 
	Kent Overstreet <kent.overstreet@linux.dev>, Kees Cook <keescook@chromium.org>, 
	Andrew Morton <akpm@linux-foundation.org>, Tycho Andersen <tandersen@netflix.com>, 
	Jens Axboe <axboe@kernel.dk>, Aleksa Sarai <cyphar@cyphar.com>
Subject: Re: [PATCH 1/3] tracing: Remove dependency of saved_cmdlines_buffer
 on PID_MAX_DEFAULT
Message-ID: <eteswsookugqwr5pju5fuzc6m2wly4pxrbp3y2umke6ojvwo3x@pwjqsu77yh6s>
References: <20240408145819.8787-1-mkoutny@suse.com>
 <20240408145819.8787-2-mkoutny@suse.com>
 <20240409110126.651e94cb@gandalf.local.home>
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On Tue, Apr 09, 2024 at 11:01:26AM GMT, Steven Rostedt <rostedt@goodmis.org=
> wrote:
> > -	tpid =3D pid & (PID_MAX_DEFAULT - 1);
> > +	tpid =3D pid % PID_MAP_SIZE;
>=20
> Does that compile to the same? This is a fast path.

I didn't check.
If fast is the intetion, I would change it to something
like BUILD_BUG_ON(!(PID_MAP_SIZE % 2)) and keep the bit operation
without reliance on compiler optimizations.

Thanks for the response (I may not follow up on this single commit
though).

Michal

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