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Re: [PATCH v2 2.6.38-rc8-tip 7/20] 7: uprobes: store/restore original instruction.
- From: Stephen Wilson <wilsons at start dot ca>
- To: Steven Rostedt <rostedt at goodmis dot org>
- Cc: Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, Peter Zijlstra <peterz at infradead dot org>, Ingo Molnar <mingo at elte dot hu>, Linux-mm <linux-mm at kvack dot org>, Arnaldo Carvalho de Melo <acme at infradead dot org>, Linus Torvalds <torvalds at linux-foundation dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Christoph Hellwig <hch at infradead dot org>, Andi Kleen <andi at firstfloor dot org>, Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, Oleg Nesterov <oleg at redhat dot com>, LKML <linux-kernel at vger dot kernel dot org>, Jim Keniston <jkenisto at linux dot vnet dot ibm dot com>, Roland McGrath <roland at hack dot frob dot com>, SystemTap <systemtap at sources dot redhat dot com>, Andrew Morton <akpm at linux-foundation dot org>, "Paul E. McKenney" <paulmck at linux dot vnet dot ibm dot com>
- Date: Tue, 15 Mar 2011 12:15:30 -0400
- Subject: Re: [PATCH v2 2.6.38-rc8-tip 7/20] 7: uprobes: store/restore original instruction.
- References: <20110314133403.27435.7901.sendpatchset@localhost6.localdomain6> <20110314133522.27435.45121.sendpatchset@localhost6.localdomain6> <20110314180914.GA18855@fibrous.localdomain> <20110315092247.GW24254@linux.vnet.ibm.com> <1300196879.9910.271.camel@gandalf.stny.rr.com>
On Tue, Mar 15, 2011 at 09:47:59AM -0400, Steven Rostedt wrote:
> > rcu_read_lock()
> > if (mm->owner) {
> > get_task_struct(mm->owner)
> > tsk = mm->owner;
> > }
> > rcu_read_unlock()
> > if (!tsk)
> > return ret;
> >
> > Agree?
>
> Or:
>
> rcu_read_lock();
> tsk = mm->owner;
> if (tsk)
> get_task_struct(tsk);
> rcu_read_unlock();
> if (!tsk)
> return ret;
>
> Probably looks cleaner.
Yes, plus we should do "tsk = rcu_dereference(mm->owner);" and wrap the
whole thing in a static uprobes_get_mm_owner() or similar.
--
steve