Messages in this thread | | | Date | Mon, 4 May 2009 21:36:24 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 2/2] ptrace: do not use task_lock() for attach |
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On 05/04, Roland McGrath wrote: > > This looks good to me overall. It might be worth slicing it into two or > more patches, just for bisect paranoia. (e.g. PF_KTHREAD; task_lock in > ptrace_attach; task_lock in ptrace_traceme.)
OK,
> I think it merits a comment that the PF_KTHREAD check does not need any > interlock because daemonize() will detach ptrace via reparent_to_kthreadd() > after it sets PF_KTHREAD. (vs the old ->mm check under task_lock.)
Agreed, but actually the patch doesn't make the difference wrt daemonize(). currently ptrace_attach() can take task_lock() just before daemonize() calls exit_mm().
> It is worth noting that this changes the security_ptrace_traceme() call so > it's no longer under task_lock(). I can't see any way the LSM hooks care, > but it is a change.
Yes, good point.
> You also didn't mention the s/|=/=/ changes. Those are correct, we've > already agreed, but the commit log should mention that this subtle change > was intentional.
Yes! Forgot to mention, thanks.
Oleg.
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