LCOV - code coverage report
Current view: top level - include/linux - rcu_sync.h (source / functions) Hit Total Coverage
Test: Real Lines: 1 1 100.0 %
Date: 2020-10-17 15:46:16 Functions: 0 0 -
Legend: Neither, QEMU, Real, Both Branches: 0 0 -

           Branch data     Line data    Source code
       1                 :            : /* SPDX-License-Identifier: GPL-2.0+ */
       2                 :            : /*
       3                 :            :  * RCU-based infrastructure for lightweight reader-writer locking
       4                 :            :  *
       5                 :            :  * Copyright (c) 2015, Red Hat, Inc.
       6                 :            :  *
       7                 :            :  * Author: Oleg Nesterov <oleg@redhat.com>
       8                 :            :  */
       9                 :            : 
      10                 :            : #ifndef _LINUX_RCU_SYNC_H_
      11                 :            : #define _LINUX_RCU_SYNC_H_
      12                 :            : 
      13                 :            : #include <linux/wait.h>
      14                 :            : #include <linux/rcupdate.h>
      15                 :            : 
      16                 :            : /* Structure to mediate between updaters and fastpath-using readers.  */
      17                 :            : struct rcu_sync {
      18                 :            :         int                     gp_state;
      19                 :            :         int                     gp_count;
      20                 :            :         wait_queue_head_t       gp_wait;
      21                 :            : 
      22                 :            :         struct rcu_head         cb_head;
      23                 :            : };
      24                 :            : 
      25                 :            : /**
      26                 :            :  * rcu_sync_is_idle() - Are readers permitted to use their fastpaths?
      27                 :            :  * @rsp: Pointer to rcu_sync structure to use for synchronization
      28                 :            :  *
      29                 :            :  * Returns true if readers are permitted to use their fastpaths.  Must be
      30                 :            :  * invoked within some flavor of RCU read-side critical section.
      31                 :            :  */
      32                 :            : static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
      33                 :            : {
      34                 :            :         RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
      35                 :            :                          "suspicious rcu_sync_is_idle() usage");
      36                 :          3 :         return !READ_ONCE(rsp->gp_state); /* GP_IDLE */
      37                 :            : }
      38                 :            : 
      39                 :            : extern void rcu_sync_init(struct rcu_sync *);
      40                 :            : extern void rcu_sync_enter_start(struct rcu_sync *);
      41                 :            : extern void rcu_sync_enter(struct rcu_sync *);
      42                 :            : extern void rcu_sync_exit(struct rcu_sync *);
      43                 :            : extern void rcu_sync_dtor(struct rcu_sync *);
      44                 :            : 
      45                 :            : #define __RCU_SYNC_INITIALIZER(name) {                                  \
      46                 :            :                 .gp_state = 0,                                          \
      47                 :            :                 .gp_count = 0,                                          \
      48                 :            :                 .gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \
      49                 :            :         }
      50                 :            : 
      51                 :            : #define DEFINE_RCU_SYNC(name)   \
      52                 :            :         struct rcu_sync name = __RCU_SYNC_INITIALIZER(name)
      53                 :            : 
      54                 :            : #endif /* _LINUX_RCU_SYNC_H_ */
    

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