Re: [PATCH 0/7] uprobes: single-step fixes
From: Oleg Nesterov
Date: Sat Sep 08 2012 - 13:04:14 EST
On 09/03, Oleg Nesterov wrote:
>
> Sebastian, I changed your patches a bit:
>
> 1/7:
>
> - Change the subject and update the changelog. In particular,
> s/utrace/uprobes/. I am wondering where this typo came from ;)
Hmm. I just noticed this patch is buggy. arch_uprobe_disable_step(&uprobe->arch)
is not safe after put_uprobe().
Srikar, I fixed this in my tree with the following change,
--- kernel/events/uprobes.c~ 2012-09-02 16:52:54.000000000 +0200
+++ kernel/events/uprobes.c 2012-09-08 18:56:44.000000000 +0200
@@ -1536,10 +1536,10 @@ static void handle_singlestep(struct upr
else
WARN_ON_ONCE(1);
+ arch_uprobe_disable_step(&uprobe->arch);
put_uprobe(uprobe);
utask->active_uprobe = NULL;
utask->state = UTASK_RUNNING;
- arch_uprobe_disable_step(&uprobe->arch);
xol_free_insn_slot(current);
spin_lock_irq(¤t->sighand->siglock);
I hope your ack is still valid.
And this also allows us to rely on utask->state in disable_step(), see
the new 8/7 I'll send in a minute. I was going to fix this later, but
I just realized that "disable if trapped" is more buggy than I thought.
Assuming that you are agree with 6 and 8. I'd prefer the new one as a
separate change, but if you prefer to join them please let me know.
Oleg.
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