linux-kernel - Re: [RFC PATCH v2 06/20] tracing/filters: Optimise scalar vs cpumask filtering when the user mask is a single CPU

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Message-ID: <20230731141626.1b180ab1@gandalf.local.home>
Date:   Mon, 31 Jul 2023 14:16:26 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Dan Carpenter <dan.carpenter@...aro.org>
Cc:     Valentin Schneider <vschneid@...hat.com>,
        linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, kvm@...r.kernel.org, linux-mm@...ck.org,
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        linux-kselftest@...r.kernel.org,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
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Subject: Re: [RFC PATCH v2 06/20] tracing/filters: Optimise scalar vs
 cpumask filtering when the user mask is a single CPU

On Mon, 31 Jul 2023 19:03:04 +0300
Dan Carpenter <dan.carpenter@...aro.org> wrote:

> > > > Nit, the above can be written as:
> > > > 
> > > > 			pred->op = pret->op != OP_BAND ? : OP_EQ;
> > > >     
> > > 
> > > Heh.  Those are not equivalent.  The right way to write this is:  
> > 
> > You mean because of my typo?  
> 
> No, I hadn't seen the s/pred/pret/ typo.  Your code does:
> 
> 	if (pred->op != OP_BAND)
> 		pred->op = true;
> 	else
> 		pred->op OP_EQ;

Ah, for some reason I was thinking the ? : just was just a nop, but I guess
it is to assign the cond value :-/

But of course every place I've done that, it was the condition value I
wanted, which was the same as the value being assigned.

Thanks,

-- Steve