arch/x86/include/asm/qspinlock.h:17:9: sparse: context imbalance in 'wake_futex_pi' - unexpected unlock

arch/x86/include/asm/qspinlock.h:17:9: sparse: context imbalance in 'wake_futex_pi' - unexpected unlock

[kbuild test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   2868b2513aa732a99ea4a0a6bf10dc93c1f3dac2
commit: bebe5b514345f09be2c15e414d076b02ecb9cce8 futex: Futex_unlock_pi() determinism
date:   7 weeks ago
reproduce:
        # apt-get install sparse
        git checkout bebe5b514345f09be2c15e414d076b02ecb9cce8
        make ARCH=x86_64 allmodconfig
        make C=1 CF=-D__CHECK_ENDIAN__


sparse warnings: (new ones prefixed by >>)

   arch/x86/include/asm/futex.h:113:16: sparse: incorrect type in initializer (different address spaces)
   arch/x86/include/asm/futex.h:113:16:    expected unsigned int [noderef] [usertype] <asn:1>*__uval
   arch/x86/include/asm/futex.h:113:16:    got unsigned int [usertype] *uval
   arch/x86/include/asm/futex.h:113:16: sparse: dereference of noderef expression
>> arch/x86/include/asm/qspinlock.h:17:9: sparse: context imbalance in 'wake_futex_pi' - unexpected unlock
   kernel/futex.c:1577:33: sparse: context imbalance in 'futex_wake_op' - different lock contexts for basic block
   kernel/futex.c:1859:41: sparse: context imbalance in 'futex_requeue' - different lock contexts for basic block
   include/linux/spinlock_api_smp.h:169:9: sparse: context imbalance in 'fixup_pi_state_owner' - unexpected unlock
   kernel/futex.c:2377:13: sparse: context imbalance in 'futex_wait_queue_me' - unexpected unlock
   kernel/futex.c:2480:9: sparse: context imbalance in 'futex_wait_setup' - different lock contexts for basic block
   kernel/futex.c:2748:12: sparse: context imbalance in 'futex_unlock_pi' - different lock contexts for basic block
   kernel/futex.c:3013:29: sparse: context imbalance in 'futex_wait_requeue_pi' - unexpected unlock

vim +/wake_futex_pi +17 arch/x86/include/asm/qspinlock.h

d73a3397 Waiman Long            2015-04-24   1  #ifndef _ASM_X86_QSPINLOCK_H
d73a3397 Waiman Long            2015-04-24   2  #define _ASM_X86_QSPINLOCK_H
d73a3397 Waiman Long            2015-04-24   3  
2aa79af6 Peter Zijlstra (Intel  2015-04-24   4) #include <asm/cpufeature.h>
d73a3397 Waiman Long            2015-04-24   5  #include <asm-generic/qspinlock_types.h>
f233f7f1 Peter Zijlstra (Intel  2015-04-24   6) #include <asm/paravirt.h>
d73a3397 Waiman Long            2015-04-24   7  
d73a3397 Waiman Long            2015-04-24   8  #define	queued_spin_unlock queued_spin_unlock
d73a3397 Waiman Long            2015-04-24   9  /**
d73a3397 Waiman Long            2015-04-24  10   * queued_spin_unlock - release a queued spinlock
d73a3397 Waiman Long            2015-04-24  11   * @lock : Pointer to queued spinlock structure
d73a3397 Waiman Long            2015-04-24  12   *
d73a3397 Waiman Long            2015-04-24  13   * A smp_store_release() on the least-significant byte.
d73a3397 Waiman Long            2015-04-24  14   */
f233f7f1 Peter Zijlstra (Intel  2015-04-24  15) static inline void native_queued_spin_unlock(struct qspinlock *lock)
d73a3397 Waiman Long            2015-04-24  16  {
d73a3397 Waiman Long            2015-04-24 @17  	smp_store_release((u8 *)lock, 0);
d73a3397 Waiman Long            2015-04-24  18  }
d73a3397 Waiman Long            2015-04-24  19  
f233f7f1 Peter Zijlstra (Intel  2015-04-24  20) #ifdef CONFIG_PARAVIRT_SPINLOCKS
f233f7f1 Peter Zijlstra (Intel  2015-04-24  21) extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
f233f7f1 Peter Zijlstra (Intel  2015-04-24  22) extern void __pv_init_lock_hash(void);
f233f7f1 Peter Zijlstra (Intel  2015-04-24  23) extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
f233f7f1 Peter Zijlstra (Intel  2015-04-24  24) extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock);
f233f7f1 Peter Zijlstra (Intel  2015-04-24  25) 

:::::: The code at line 17 was first introduced by commit
:::::: d73a33973f16ab6703e75ea00edee857afa3406e locking/qspinlock, x86: Enable x86-64 to use queued spinlocks

:::::: TO: Waiman Long <Waiman.Long@hp.com>
:::::: CC: Ingo Molnar <mingo@kernel.org>

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