include/linux/rwbase_rt.h

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #ifndef _LINUX_RWBASE_RT_H
   3 #define _LINUX_RWBASE_RT_H
   4
   5 #include <linux/rtmutex.h>
   6 #include <linux/atomic.h>
   7
   8 #define READER_BIAS             (1U << 31)
   9 #define WRITER_BIAS             (1U << 30)
  10
  11 struct rwbase_rt {
  12         atomic_t                readers;
  13         struct rt_mutex_base    rtmutex;
  14 };
  15
  16 #define __RWBASE_INITIALIZER(name)                              \
  17 {                                                               \
  18         .readers = ATOMIC_INIT(READER_BIAS),                    \
  19         .rtmutex = __RT_MUTEX_BASE_INITIALIZER(name.rtmutex),   \
  20 }
  21
  22 #define init_rwbase_rt(rwbase)                                  \
  23         do {                                                    \
  24                 rt_mutex_base_init(&(rwbase)->rtmutex);         \
  25                 atomic_set(&(rwbase)->readers, READER_BIAS);    \
  26         } while (0)
  27
  28
  29 static __always_inline bool rw_base_is_locked(struct rwbase_rt *rwb)
  30 {
  31         return atomic_read(&rwb->readers) != READER_BIAS;
  32 }
  33
  34 static __always_inline bool rw_base_is_contended(struct rwbase_rt *rwb)
  35 {
  36         return atomic_read(&rwb->readers) > 0;
  37 }
  38
  39 #endif /* _LINUX_RWBASE_RT_H */