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    SubjectRe: [RFC][PATCH 6/7] lockdep: Maintain rw_state entries in locklist
    On Sun, Apr 17, 2011 at 11:45:11AM +0200, Peter Zijlstra wrote:
    > From: Gautham R Shenoy <ego@in.ibm.com>
    >
    > The dependencies are currently maintained using a structure named
    > locklist. For a dependency A --> B, it saves B's lock_class in an
    > entry that would be linked to A's locks_after list.
    >
    > However, in order to make use of the split chains introduced in the
    > previous patch, we need to enhance this infrastructure to save the
    > read/write states of A and B for each dependency such that we might
    > distinguish between the read and write chains.
    >
    > Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
    > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    > ---
    > include/linux/lockdep.h | 6 ++++++
    > kernel/lockdep.c | 23 +++++++++++++++++------
    > 2 files changed, 23 insertions(+), 6 deletions(-)
    >
    > @@ -1690,6 +1694,8 @@ check_prev_add(struct task_struct *curr,
    > if (entry->dep_class == hlock_class(next)) {
    > if (distance == 1)
    > entry->distance = 1;
    > + entry->this_lock_rw_state |= prev->rw_state;
    > + entry->dep_lock_rw_state |= next->rw_state;

    If we could do this and return,

    > return 2;
    > }
    > }
    > @@ -1697,19 +1703,24 @@ check_prev_add(struct task_struct *curr,
    > if (!trylock_loop && !save_trace(&trace))
    > return 0;
    >
    > + list_for_each_entry(entry, &hlock_class(next)->locks_before, entry) {
    > + if (entry->dep_class == hlock_class(prev)) {
    > + entry->this_lock_rw_state |= next->rw_state;
    > + entry->dep_lock_rw_state |= prev->rw_state;
    > + }
    > + }
    > +

    Do we have any change to do above?

    Or am I missing something?

    Thanks,
    Yong


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