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

From: kbuild test robot
Date: Tue May 09 2017 - 12:06:02 EST


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@xxxxxx>
:::::: CC: Ingo Molnar <mingo@xxxxxxxxxx>

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