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 int ww_mutex_trylock(struct ww_mutex *lock, struct ww_acquire_ctx *ww_ctx)
  13 {
  14         struct rt_mutex *rtm = &lock->base;
  15
  16         if (!ww_ctx)
  17                 return rt_mutex_trylock(rtm);
  18
  19         /*
  20          * Reset the wounded flag after a kill. No other process can
  21          * race and wound us here, since they can't have a valid owner
  22          * pointer if we don't have any locks held.
  23          */
  24         if (ww_ctx->acquired == 0)
  25                 ww_ctx->wounded = 0;
  26
  27         if (__rt_mutex_trylock(&rtm->rtmutex)) {
  28                 ww_mutex_set_context_fastpath(lock, ww_ctx);
  29                 mutex_acquire_nest(&rtm->dep_map, 0, 1, &ww_ctx->dep_map, _RET_IP_);
  30                 return 1;
  31         }
  32
  33         return 0;
  34 }
  35 EXPORT_SYMBOL(ww_mutex_trylock);
  36
  37 static int __sched
  38 __ww_rt_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ww_ctx,
  39                    unsigned int state, unsigned long ip)
  40 {
  41         struct lockdep_map __maybe_unused *nest_lock = NULL;
  42         struct rt_mutex *rtm = &lock->base;
  43         int ret;
  44
  45         might_sleep();
  46
  47         if (ww_ctx) {
  48                 if (unlikely(ww_ctx == READ_ONCE(lock->ctx)))
  49                         return -EALREADY;
  50
  51                 /*
  52                  * Reset the wounded flag after a kill. No other process can
  53                  * race and wound us here, since they can't have a valid owner
  54                  * pointer if we don't have any locks held.
  55                  */
  56                 if (ww_ctx->acquired == 0)
  57                         ww_ctx->wounded = 0;
  58
  59 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  60                 nest_lock = &ww_ctx->dep_map;
  61 #endif
  62         }
  63         mutex_acquire_nest(&rtm->dep_map, 0, 0, nest_lock, ip);
  64
  65         if (likely(rt_mutex_cmpxchg_acquire(&rtm->rtmutex, NULL, current))) {
  66                 if (ww_ctx)
  67                         ww_mutex_set_context_fastpath(lock, ww_ctx);
  68                 return 0;
  69         }
  70
  71         ret = rt_mutex_slowlock(&rtm->rtmutex, ww_ctx, state);
  72
  73         if (ret)
  74                 mutex_release(&rtm->dep_map, ip);
  75         return ret;
  76 }
  77
  78 int __sched
  79 ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
  80 {
  81         return __ww_rt_mutex_lock(lock, ctx, TASK_UNINTERRUPTIBLE, _RET_IP_);
  82 }
  83 EXPORT_SYMBOL(ww_mutex_lock);
  84
  85 int __sched
  86 ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
  87 {
  88         return __ww_rt_mutex_lock(lock, ctx, TASK_INTERRUPTIBLE, _RET_IP_);
  89 }
  90 EXPORT_SYMBOL(ww_mutex_lock_interruptible);
  91
  92 void __sched ww_mutex_unlock(struct ww_mutex *lock)
  93 {
  94         struct rt_mutex *rtm = &lock->base;
  95
  96         __ww_mutex_unlock(lock);
  97
  98         mutex_release(&rtm->dep_map, _RET_IP_);
  99         __rt_mutex_unlock(&rtm->rtmutex);
 100 }
 101 EXPORT_SYMBOL(ww_mutex_unlock);