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    SubjectRe: [RFC][PATCH 2/6] x86, nmi: create new NMI handler routines
    On Wed, 2011-08-24 at 13:44 -0400, Don Zickus wrote:
    > > > + rcu_read_lock();
    > > > + a = rcu_dereference_raw(*ap);
    > >
    > > The reason for rcu_dereference_raw() is to prevent lockdep from choking
    > > due to being called from an NMI handler, correct? If so, please add a
    > > comment to this effect on this and similar uses.
    > That sounds right. But honestly, I just copied what notifier_call_chain
    > had. Regardless, I will make sure to document that in my next version.
    > Thanks!

    Not quite right, nmi_enter() does lockdep_disable() and makes
    lock_is_held() return always true.

    I think this (and the other sites) could do with rcu_dereference_check(,
    lockdep_is_held(&desc->lock)); not that it wouldn't be anything but
    documentation since the actual test isn't working from NMI context but I
    do think its worth it for that alone.

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      Last update: 2011-08-24 19:53    [W:0.019 / U:292.712 seconds]
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