Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fix from Ingo Molnar: "A single fix for a locking self-test crash" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/pvqspinlock: Fix kernel panic in locking-selftest
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5e5013c6b5
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@ -4,6 +4,7 @@
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#include <linux/hash.h>
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#include <linux/bootmem.h>
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#include <linux/debug_locks.h>
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/*
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* Implement paravirt qspinlocks; the general idea is to halt the vcpus instead
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@ -286,15 +287,23 @@ __visible void __pv_queued_spin_unlock(struct qspinlock *lock)
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{
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struct __qspinlock *l = (void *)lock;
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struct pv_node *node;
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u8 lockval = cmpxchg(&l->locked, _Q_LOCKED_VAL, 0);
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/*
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* We must not unlock if SLOW, because in that case we must first
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* unhash. Otherwise it would be possible to have multiple @lock
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* entries, which would be BAD.
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*/
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if (likely(cmpxchg(&l->locked, _Q_LOCKED_VAL, 0) == _Q_LOCKED_VAL))
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if (likely(lockval == _Q_LOCKED_VAL))
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return;
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if (unlikely(lockval != _Q_SLOW_VAL)) {
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if (debug_locks_silent)
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return;
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WARN(1, "pvqspinlock: lock %p has corrupted value 0x%x!\n", lock, atomic_read(&lock->val));
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return;
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}
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/*
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* Since the above failed to release, this must be the SLOW path.
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* Therefore start by looking up the blocked node and unhashing it.
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