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    Subject[tip:locking/core] locking/lockdep: Verify whether lock objects are small enough to be used as class keys
    Commit-ID:  4bf508621855613ca2ac782f70c3171e0e8bb011
    Gitweb: https://git.kernel.org/tip/4bf508621855613ca2ac782f70c3171e0e8bb011
    Author: Bart Van Assche <bvanassche@acm.org>
    AuthorDate: Thu, 14 Feb 2019 15:00:52 -0800
    Committer: Ingo Molnar <mingo@kernel.org>
    CommitDate: Thu, 28 Feb 2019 07:55:46 +0100

    locking/lockdep: Verify whether lock objects are small enough to be used as class keys

    Signed-off-by: Bart Van Assche <bvanassche@acm.org>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Johannes Berg <johannes@sipsolutions.net>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Waiman Long <longman@redhat.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: johannes.berg@intel.com
    Cc: tj@kernel.org
    Link: https://lkml.kernel.org/r/20190214230058.196511-18-bvanassche@acm.org
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    kernel/locking/lockdep.c | 11 +++++++++++
    1 file changed, 11 insertions(+)

    diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
    index 630be9ac6253..84427441824e 100644
    --- a/kernel/locking/lockdep.c
    +++ b/kernel/locking/lockdep.c
    @@ -758,6 +758,17 @@ static bool assign_lock_key(struct lockdep_map *lock)
    {
    unsigned long can_addr, addr = (unsigned long)lock;

    +#ifdef __KERNEL__
    + /*
    + * lockdep_free_key_range() assumes that struct lock_class_key
    + * objects do not overlap. Since we use the address of lock
    + * objects as class key for static objects, check whether the
    + * size of lock_class_key objects does not exceed the size of
    + * the smallest lock object.
    + */
    + BUILD_BUG_ON(sizeof(struct lock_class_key) > sizeof(raw_spinlock_t));
    +#endif
    +
    if (__is_kernel_percpu_address(addr, &can_addr))
    lock->key = (void *)can_addr;
    else if (__is_module_percpu_address(addr, &can_addr))
    \
     
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