LCOV - code coverage report
Current view: top level - include/asm-generic - qspinlock.h (source / functions) Hit Total Coverage
Test: combined.info Lines: 16 18 88.9 %
Date: 2022-03-28 13:20:08 Functions: 0 0 -
Branches: 8 42 19.0 %

           Branch data     Line data    Source code
       1                 :            : /* SPDX-License-Identifier: GPL-2.0-or-later */
       2                 :            : /*
       3                 :            :  * Queued spinlock
       4                 :            :  *
       5                 :            :  * (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P.
       6                 :            :  * (C) Copyright 2015 Hewlett-Packard Enterprise Development LP
       7                 :            :  *
       8                 :            :  * Authors: Waiman Long <waiman.long@hpe.com>
       9                 :            :  */
      10                 :            : #ifndef __ASM_GENERIC_QSPINLOCK_H
      11                 :            : #define __ASM_GENERIC_QSPINLOCK_H
      12                 :            : 
      13                 :            : #include <asm-generic/qspinlock_types.h>
      14                 :            : 
      15                 :            : /**
      16                 :            :  * queued_spin_is_locked - is the spinlock locked?
      17                 :            :  * @lock: Pointer to queued spinlock structure
      18                 :            :  * Return: 1 if it is locked, 0 otherwise
      19                 :            :  */
      20                 :    1152353 : static __always_inline int queued_spin_is_locked(struct qspinlock *lock)
      21                 :            : {
      22                 :            :         /*
      23                 :            :          * Any !0 state indicates it is locked, even if _Q_LOCKED_VAL
      24                 :            :          * isn't immediately observable.
      25                 :            :          */
      26                 :    1152353 :         return atomic_read(&lock->val);
      27                 :            : }
      28                 :            : 
      29                 :            : /**
      30                 :            :  * queued_spin_value_unlocked - is the spinlock structure unlocked?
      31                 :            :  * @lock: queued spinlock structure
      32                 :            :  * Return: 1 if it is unlocked, 0 otherwise
      33                 :            :  *
      34                 :            :  * N.B. Whenever there are tasks waiting for the lock, it is considered
      35                 :            :  *      locked wrt the lockref code to avoid lock stealing by the lockref
      36                 :            :  *      code and change things underneath the lock. This also allows some
      37                 :            :  *      optimizations to be applied without conflict with lockref.
      38                 :            :  */
      39                 :   18114221 : static __always_inline int queued_spin_value_unlocked(struct qspinlock lock)
      40                 :            : {
      41   [ +  -  +  -  :   18114221 :         return !atomic_read(&lock.val);
          +  -  -  -  -  
             -  +  -  +  
                      - ]
      42                 :            : }
      43                 :            : 
      44                 :            : /**
      45                 :            :  * queued_spin_is_contended - check if the lock is contended
      46                 :            :  * @lock : Pointer to queued spinlock structure
      47                 :            :  * Return: 1 if lock contended, 0 otherwise
      48                 :            :  */
      49                 :      30657 : static __always_inline int queued_spin_is_contended(struct qspinlock *lock)
      50                 :            : {
      51         [ +  - ]:      30657 :         return atomic_read(&lock->val) & ~_Q_LOCKED_MASK;
      52                 :            : }
      53                 :            : /**
      54                 :            :  * queued_spin_trylock - try to acquire the queued spinlock
      55                 :            :  * @lock : Pointer to queued spinlock structure
      56                 :            :  * Return: 1 if lock acquired, 0 if failed
      57                 :            :  */
      58                 :     489421 : static __always_inline int queued_spin_trylock(struct qspinlock *lock)
      59                 :            : {
      60         [ #  # ]:     489421 :         u32 val = atomic_read(&lock->val);
      61                 :            : 
      62   [ +  -  #  # ]:     489421 :         if (unlikely(val))
      63                 :            :                 return 0;
      64                 :            : 
      65   [ #  #  #  # ]:     489421 :         return likely(atomic_try_cmpxchg_acquire(&lock->val, &val, _Q_LOCKED_VAL));
      66                 :            : }
      67                 :            : 
      68                 :            : extern void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
      69                 :            : 
      70                 :            : /**
      71                 :            :  * queued_spin_lock - acquire a queued spinlock
      72                 :            :  * @lock: Pointer to queued spinlock structure
      73                 :            :  */
      74                 :   33650060 : static __always_inline void queued_spin_lock(struct qspinlock *lock)
      75                 :            : {
      76                 :   33650060 :         u32 val = 0;
      77                 :            : 
      78   [ +  -  #  #  :   33650060 :         if (likely(atomic_try_cmpxchg_acquire(&lock->val, &val, _Q_LOCKED_VAL)))
          #  #  #  #  #  
             #  #  #  #  
                      # ]
      79                 :   33650060 :                 return;
      80                 :            : 
      81                 :          0 :         queued_spin_lock_slowpath(lock, val);
      82                 :            : }
      83                 :            : 
      84                 :            : #ifndef queued_spin_unlock
      85                 :            : /**
      86                 :            :  * queued_spin_unlock - release a queued spinlock
      87                 :            :  * @lock : Pointer to queued spinlock structure
      88                 :            :  */
      89                 :   60966216 : static __always_inline void queued_spin_unlock(struct qspinlock *lock)
      90                 :            : {
      91                 :            :         /*
      92                 :            :          * unlock() needs release semantics:
      93                 :            :          */
      94         [ #  # ]:   60793166 :         smp_store_release(&lock->locked, 0);
      95                 :          0 : }
      96                 :            : #endif
      97                 :            : 
      98                 :            : #ifndef virt_spin_lock
      99                 :            : static __always_inline bool virt_spin_lock(struct qspinlock *lock)
     100                 :            : {
     101                 :            :         return false;
     102                 :            : }
     103                 :            : #endif
     104                 :            : 
     105                 :            : /*
     106                 :            :  * Remapping spinlock architecture specific functions to the corresponding
     107                 :            :  * queued spinlock functions.
     108                 :            :  */
     109                 :            : #define arch_spin_is_locked(l)          queued_spin_is_locked(l)
     110                 :            : #define arch_spin_is_contended(l)       queued_spin_is_contended(l)
     111                 :            : #define arch_spin_value_unlocked(l)     queued_spin_value_unlocked(l)
     112                 :            : #define arch_spin_lock(l)               queued_spin_lock(l)
     113                 :            : #define arch_spin_trylock(l)            queued_spin_trylock(l)
     114                 :            : #define arch_spin_unlock(l)             queued_spin_unlock(l)
     115                 :            : 
     116                 :            : #endif /* __ASM_GENERIC_QSPINLOCK_H */

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