linux-kernel - Re: lockdep trace from posix timers

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]

Date:	Mon, 20 Aug 2012 17:27:16 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	rostedt <rostedt@...dmis.org>, dhowells <dhowells@...hat.com>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: lockdep trace from posix timers

On Mon, 2012-08-20 at 17:10 +0200, Peter Zijlstra wrote:
> On Mon, 2012-08-20 at 16:59 +0200, Oleg Nesterov wrote:
> > On 08/20, Peter Zijlstra wrote:
> > >
> > >  task_work_cancel(struct task_struct *task, task_work_func_t func)
> > >  {
> > > ...
> > > +
> > > +again:
> > > +	workp = &task->task_works;
> > > +	work = *workp;
> > > +	while (work) {
> > > +		if (work->func == func) {
> > 
> > But this all can race with task_work_run() if task != current.
> > 
> > This "work" can be freed/reused. And it should only return !NULL
> > if twork->func() was not called.
> 
> Ah, because we could be iterating the list after the xchg done by run.

I guess we could steal the entire list and requeue it afterwards and
lift TIF_NOTIFY_RESUME along with it.. but I can't say that's pretty.




--
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/