LCOV - code coverage report
Current view: top level - include/linux - rcuwait.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                 :            : #ifndef _LINUX_RCUWAIT_H_
       3                 :            : #define _LINUX_RCUWAIT_H_
       4                 :            : 
       5                 :            : #include <linux/rcupdate.h>
       6                 :            : 
       7                 :            : /*
       8                 :            :  * rcuwait provides a way of blocking and waking up a single
       9                 :            :  * task in an rcu-safe manner.
      10                 :            :  *
      11                 :            :  * The only time @task is non-nil is when a user is blocked (or
      12                 :            :  * checking if it needs to) on a condition, and reset as soon as we
      13                 :            :  * know that the condition has succeeded and are awoken.
      14                 :            :  */
      15                 :            : struct rcuwait {
      16                 :            :         struct task_struct __rcu *task;
      17                 :            : };
      18                 :            : 
      19                 :            : #define __RCUWAIT_INITIALIZER(name)             \
      20                 :            :         { .task = NULL, }
      21                 :            : 
      22                 :            : static inline void rcuwait_init(struct rcuwait *w)
      23                 :            : {
      24                 :          3 :         w->task = NULL;
      25                 :            : }
      26                 :            : 
      27                 :            : extern void rcuwait_wake_up(struct rcuwait *w);
      28                 :            : 
      29                 :            : /*
      30                 :            :  * The caller is responsible for locking around rcuwait_wait_event(),
      31                 :            :  * such that writes to @task are properly serialized.
      32                 :            :  */
      33                 :            : #define rcuwait_wait_event(w, condition)                                \
      34                 :            : ({                                                                      \
      35                 :            :         rcu_assign_pointer((w)->task, current);                              \
      36                 :            :         for (;;) {                                                      \
      37                 :            :                 /*                                                      \
      38                 :            :                  * Implicit barrier (A) pairs with (B) in               \
      39                 :            :                  * rcuwait_wake_up().                                   \
      40                 :            :                  */                                                     \
      41                 :            :                 set_current_state(TASK_UNINTERRUPTIBLE);                \
      42                 :            :                 if (condition)                                          \
      43                 :            :                         break;                                          \
      44                 :            :                                                                         \
      45                 :            :                 schedule();                                             \
      46                 :            :         }                                                               \
      47                 :            :                                                                         \
      48                 :            :         WRITE_ONCE((w)->task, NULL);                                 \
      49                 :            :         __set_current_state(TASK_RUNNING);                              \
      50                 :            : })
      51                 :            : 
      52                 :            : #endif /* _LINUX_RCUWAIT_H_ */
    

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