linux-kernel - Re: Q: perf_event && event->owner

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20101109165805.GA6971@redhat.com>
Date:	Tue, 9 Nov 2010 17:58:05 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Alan Stern <stern@...land.harvard.edu>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
	Prasad <prasad@...ux.vnet.ibm.com>,
	Roland McGrath <roland@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: Q: perf_event && event->owner

On 11/09, Peter Zijlstra wrote:
>
> On Tue, 2010-11-09 at 16:57 +0100, Oleg Nesterov wrote:
> >
> > If the creator of perf_event dies, nobody can use its ->perf_event_list
> > anyway. What is the point to keep the reference to the dead task_struct
> > and preserve this ->perf_event_list?
>
> But when the owner dies it will close all its fds, which means it will
> clear its tsk->perf_event_list, no? (With exception of the case where
> the fd was passed through a unix-socket to another process).

fork(), pthread_create(). Only __fput() calls ->release, when the last
reference to file goes away.

And ptrace(), it doesn't use sys_perf_event_open() to create the event.

Oleg.

--
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/