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    Subject[PATCH RT 07/19] locking/lockdep: Don't complain about incorrect name for no validate class
    Date
    From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

    v4.14.137-rt65-rc1 stable review patch.
    If anyone has any objections, please let me know.

    -----------


    [ Upstream commit 978315462d3ea3cf6cfacd34c563ec1eb02a3aa5 ]

    It is possible to ignore the validation for a certain lock by using:

    lockdep_set_novalidate_class()

    on it. Each invocation will assign a new name to the class it created
    for created __lockdep_no_validate__. That means that once
    lockdep_set_novalidate_class() has been used on two locks then
    class->name won't match lock->name for the first lock triggering the
    warning.

    So ignore changed non-matching ->name pointer for the special
    __lockdep_no_validate__ class.

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Will Deacon <will.deacon@arm.com>
    Link: http://lkml.kernel.org/r/20190517212234.32611-1-bigeasy@linutronix.de
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Tom Zanussi <zanussi@kernel.org>
    ---
    kernel/locking/lockdep.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
    index e576d234f3ea..f194de27123d 100644
    --- a/kernel/locking/lockdep.c
    +++ b/kernel/locking/lockdep.c
    @@ -719,7 +719,8 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
    * Huh! same key, different name? Did someone trample
    * on some memory? We're most confused.
    */
    - WARN_ON_ONCE(class->name != lock->name);
    + WARN_ON_ONCE(class->name != lock->name &&
    + lock->key != &__lockdep_no_validate__);
    return class;
    }
    }
    --
    2.14.1
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