linux-kernel - Re: [PATCH 1/6] perf/core: Provide a kernel-internal interface to get to performance counters

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20091101213839.28b4054a@infradead.org>
Date:	Sun, 1 Nov 2009 21:38:39 -0800
From:	Arjan van de Ven <arjan@...radead.org>
To:	Paul Mackerras <paulus@...ba.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	"K.Prasad" <prasad@...ux.vnet.ibm.com>,
	Alan Stern <stern@...land.harvard.edu>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Jan Kiszka <jan.kiszka@...mens.com>,
	Jiri Slaby <jirislaby@...il.com>,
	Li Zefan <lizf@...fujitsu.com>, Avi Kivity <avi@...hat.com>,
	Mike Galbraith <efault@....de>,
	Masami Hiramatsu <mhiramat@...hat.com>,
	Paul Mundt <lethal@...ux-sh.org>,
	Jan Kiszka <jan.kiszka@....de>
Subject: Re: [PATCH 1/6] perf/core: Provide a kernel-internal interface to
 get to performance counters

On Mon, 2 Nov 2009 14:46:55 +1100
Paul Mackerras <paulus@...ba.org> wrote:

> Frederic Weisbecker writes:
> 
> >  /*
> > + * perf_event_create_kernel_counter
> > + * MUST be called from a kernel thread.
> 
> Why?  The reason for this requirement isn't obvious to me.  It would
> be good to have the reason documented in the comment for the sake of
> people modifying the code in future.

because if you call it from another context it will attach to that
context... and go away when that context goes away...



-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/