kernel/locking/ww_rt_mutex.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * rtmutex API
   4  */
   5 #include <linux/spinlock.h>
   6 #include <linux/export.h>
   7
   8 #define RT_MUTEX_BUILD_MUTEX
   9 #define WW_RT
  10 #include "rtmutex.c"
  11
  12 static int __sched
  13 __ww_rt_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ww_ctx,
  14                    unsigned int state, unsigned long ip)
  15 {
  16         struct lockdep_map __maybe_unused *nest_lock = NULL;
  17         struct rt_mutex *rtm = &lock->base;
  18         int ret;
  19
  20         might_sleep();
  21
  22         if (ww_ctx) {
  23                 if (unlikely(ww_ctx == READ_ONCE(lock->ctx)))
  24                         return -EALREADY;
  25
  26                 /*
  27                  * Reset the wounded flag after a kill. No other process can
  28                  * race and wound us here, since they can't have a valid owner
  29                  * pointer if we don't have any locks held.
  30                  */
  31                 if (ww_ctx->acquired == 0)
  32                         ww_ctx->wounded = 0;
  33
  34 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  35                 nest_lock = &ww_ctx->dep_map;
  36 #endif
  37         }
  38         mutex_acquire_nest(&rtm->dep_map, 0, 0, nest_lock, ip);
  39
  40         if (likely(rt_mutex_cmpxchg_acquire(&rtm->rtmutex, NULL, current))) {
  41                 if (ww_ctx)
  42                         ww_mutex_set_context_fastpath(lock, ww_ctx);
  43                 return 0;
  44         }
  45
  46         ret = rt_mutex_slowlock(&rtm->rtmutex, ww_ctx, state);
  47
  48         if (ret)
  49                 mutex_release(&rtm->dep_map, ip);
  50         return ret;
  51 }
  52
  53 int __sched
  54 ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
  55 {
  56         return __ww_rt_mutex_lock(lock, ctx, TASK_UNINTERRUPTIBLE, _RET_IP_);
  57 }
  58 EXPORT_SYMBOL(ww_mutex_lock);
  59
  60 int __sched
  61 ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
  62 {
  63         return __ww_rt_mutex_lock(lock, ctx, TASK_INTERRUPTIBLE, _RET_IP_);
  64 }
  65 EXPORT_SYMBOL(ww_mutex_lock_interruptible);
  66
  67 void __sched ww_mutex_unlock(struct ww_mutex *lock)
  68 {
  69         struct rt_mutex *rtm = &lock->base;
  70
  71         __ww_mutex_unlock(lock);
  72
  73         mutex_release(&rtm->dep_map, _RET_IP_);
  74         __rt_mutex_unlock(&rtm->rtmutex);
  75 }
  76 EXPORT_SYMBOL(ww_mutex_unlock);