Commit f8635d50 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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locking/ww_mutex: Implement rtmutex based ww_mutex API functions 



Add the actual ww_mutex API functions which replace the mutex based variant
on RT enabled kernels.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211305.024057938@linutronix.de
parent add46132

kernel/locking/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -25,7 +25,7 @@ obj-$(CONFIG_LOCK_SPIN_ON_OWNER) += osq_lock.o 
obj-$(CONFIG_PROVE_LOCKING) += spinlock.o

obj-$(CONFIG_QUEUED_SPINLOCKS) += qspinlock.o

obj-$(CONFIG_RT_MUTEXES) += rtmutex_api.o

obj-$(CONFIG_PREEMPT_RT) += spinlock_rt.o

obj-$(CONFIG_PREEMPT_RT) += spinlock_rt.o ww_rt_mutex.o

obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o

obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock_debug.o

obj-$(CONFIG_QUEUED_RWLOCKS) += qrwlock.o

kernel/locking/ww_rt_mutex.c

0 → 100644
+76 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/*

 * rtmutex API

 */

#include <linux/spinlock.h>

#include <linux/export.h>



#define RT_MUTEX_BUILD_MUTEX

#define WW_RT

#include "rtmutex.c"



static int __sched

__ww_rt_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ww_ctx,

		   unsigned int state, unsigned long ip)

{

	struct lockdep_map __maybe_unused *nest_lock = NULL;

	struct rt_mutex *rtm = &lock->base;

	int ret;



	might_sleep();



	if (ww_ctx) {

		if (unlikely(ww_ctx == READ_ONCE(lock->ctx)))

			return -EALREADY;



		/*

		 * Reset the wounded flag after a kill. No other process can

		 * race and wound us here, since they can't have a valid owner

		 * pointer if we don't have any locks held.

		 */

		if (ww_ctx->acquired == 0)

			ww_ctx->wounded = 0;



#ifdef CONFIG_DEBUG_LOCK_ALLOC

		nest_lock = &ww_ctx->dep_map;

#endif

	}

	mutex_acquire_nest(&rtm->dep_map, 0, 0, nest_lock, ip);



	if (likely(rt_mutex_cmpxchg_acquire(&rtm->rtmutex, NULL, current))) {

		if (ww_ctx)

			ww_mutex_set_context_fastpath(lock, ww_ctx);

		return 0;

	}



	ret = rt_mutex_slowlock(&rtm->rtmutex, ww_ctx, state);



	if (ret)

		mutex_release(&rtm->dep_map, ip);

	return ret;

}



int __sched

ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)

{

	return __ww_rt_mutex_lock(lock, ctx, TASK_UNINTERRUPTIBLE, _RET_IP_);

}

EXPORT_SYMBOL(ww_mutex_lock);



int __sched

ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)

{

	return __ww_rt_mutex_lock(lock, ctx, TASK_INTERRUPTIBLE, _RET_IP_);

}

EXPORT_SYMBOL(ww_mutex_lock_interruptible);



void __sched ww_mutex_unlock(struct ww_mutex *lock)

{

	struct rt_mutex *rtm = &lock->base;



	__ww_mutex_unlock(lock);



	mutex_release(&rtm->dep_map, _RET_IP_);

	__rt_mutex_unlock(&rtm->rtmutex);

}

EXPORT_SYMBOL(ww_mutex_unlock);