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https://github.com/torvalds/linux
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af9f006393
With DEBUG_RT_MUTEXES enabled the fast-path rt_mutex_cmpxchg_acquire() always fails and all lock operations take the slow path. Provide a new helper inline rt_mutex_try_acquire() which maps to rt_mutex_cmpxchg_acquire() in the non-debug case. For the debug case it invokes rt_mutex_slowtrylock() which can acquire a non-contended rtmutex under full debug coverage. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20230908162254.999499-3-bigeasy@linutronix.de
102 lines
2.3 KiB
C
102 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* rtmutex API
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*/
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#include <linux/spinlock.h>
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#include <linux/export.h>
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#define RT_MUTEX_BUILD_MUTEX
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#define WW_RT
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#include "rtmutex.c"
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int ww_mutex_trylock(struct ww_mutex *lock, struct ww_acquire_ctx *ww_ctx)
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{
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struct rt_mutex *rtm = &lock->base;
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if (!ww_ctx)
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return rt_mutex_trylock(rtm);
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/*
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* Reset the wounded flag after a kill. No other process can
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* race and wound us here, since they can't have a valid owner
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* pointer if we don't have any locks held.
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*/
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if (ww_ctx->acquired == 0)
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ww_ctx->wounded = 0;
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if (__rt_mutex_trylock(&rtm->rtmutex)) {
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ww_mutex_set_context_fastpath(lock, ww_ctx);
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mutex_acquire_nest(&rtm->dep_map, 0, 1, &ww_ctx->dep_map, _RET_IP_);
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return 1;
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}
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return 0;
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}
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EXPORT_SYMBOL(ww_mutex_trylock);
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static int __sched
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__ww_rt_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ww_ctx,
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unsigned int state, unsigned long ip)
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{
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struct lockdep_map __maybe_unused *nest_lock = NULL;
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struct rt_mutex *rtm = &lock->base;
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int ret;
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might_sleep();
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if (ww_ctx) {
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if (unlikely(ww_ctx == READ_ONCE(lock->ctx)))
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return -EALREADY;
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/*
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* Reset the wounded flag after a kill. No other process can
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* race and wound us here, since they can't have a valid owner
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* pointer if we don't have any locks held.
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*/
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if (ww_ctx->acquired == 0)
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ww_ctx->wounded = 0;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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nest_lock = &ww_ctx->dep_map;
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#endif
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}
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mutex_acquire_nest(&rtm->dep_map, 0, 0, nest_lock, ip);
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if (likely(rt_mutex_try_acquire(&rtm->rtmutex))) {
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if (ww_ctx)
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ww_mutex_set_context_fastpath(lock, ww_ctx);
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return 0;
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}
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ret = rt_mutex_slowlock(&rtm->rtmutex, ww_ctx, state);
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if (ret)
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mutex_release(&rtm->dep_map, ip);
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return ret;
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}
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int __sched
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ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
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{
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return __ww_rt_mutex_lock(lock, ctx, TASK_UNINTERRUPTIBLE, _RET_IP_);
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}
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EXPORT_SYMBOL(ww_mutex_lock);
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int __sched
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ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
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{
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return __ww_rt_mutex_lock(lock, ctx, TASK_INTERRUPTIBLE, _RET_IP_);
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}
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EXPORT_SYMBOL(ww_mutex_lock_interruptible);
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void __sched ww_mutex_unlock(struct ww_mutex *lock)
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{
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struct rt_mutex *rtm = &lock->base;
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__ww_mutex_unlock(lock);
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mutex_release(&rtm->dep_map, _RET_IP_);
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__rt_mutex_unlock(&rtm->rtmutex);
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}
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EXPORT_SYMBOL(ww_mutex_unlock);
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