linux-kernel - Re: [PATCH 1/5] ptrace: remove incorrect unlikelys

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Message-Id: <200903251431.09662.borntraeger@de.ibm.com>
Date:	Wed, 25 Mar 2009 14:31:09 +0100
From:	Christian Borntraeger <borntraeger@...ibm.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Roland McGrath <roland@...hat.com>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Steven Rostedt <srostedt@...hat.com>
Subject: Re: [PATCH 1/5] ptrace: remove incorrect unlikelys

Am Wednesday 25 March 2009 08:21:29 schrieb Ingo Molnar:
> > @@ -1421,7 +1421,7 @@ asmregparm long syscall_trace_enter(struct pt_regs *regs)
> >  	    tracehook_report_syscall_entry(regs))
> >  		ret = -1L;
> >  
> > -	if (unlikely(current->audit_context)) {
> > +	if (current->audit_context) {
> 
> i suspect you got this result because you are running Fedora with 
> auditd enabled and running, right? Does SuSE and Ubuntu run with 
> auditing enabled as well? If yes then removing this annotation would 
> be right - otherwise the auditing-enabled case is considered the 
> less likely variant. (despite it being 100% wrong for your 
> particular configuration)

Auditd can be enabled/disabled via kernel command line, no? In that case
there should be no unlikely and no likely. We should not optimize for a specific
value at compile time if the value can be changed at runtime.

This patch makes a lot of sense to me.



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