Commit a1aced2b authored by Alex Kogan's avatar Alex Kogan Committed by Wei Li
Browse files

locking/qspinlock: Rename mcs lock/unlock macros and make them more generic 

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8T8XV

Reference: https://lore.kernel.org/linux-arm-kernel/20210514200743.3026725-2-alex.kogan@oracle.com



--------------------------------

The mcs unlock macro (arch_mcs_lock_handoff) should accept the value to be
stored into the lock argument as another argument. This allows using the
same macro in cases where the value to be stored when passing the lock is
different from 1.

Signed-off-by: default avatarAlex Kogan <alex.kogan@oracle.com>
Reviewed-by: default avatarSteve Sistare <steven.sistare@oracle.com>
Reviewed-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarWei Li <liwei391@huawei.com>
parent 45c76c86

arch/arm/include/asm/mcs_spinlock.h

+3 −3
Original line number Diff line number Diff line
@@ -6,7 +6,7 @@ 
#include <asm/spinlock.h>



/* MCS spin-locking. */

#define arch_mcs_spin_lock_contended(lock)				\

#define arch_mcs_spin_wait(lock)					\

do {									\

	/* Ensure prior stores are observed before we enter wfe. */	\

	smp_mb();							\
@@ -14,9 +14,9 @@ do { \ 
		wfe();							\

} while (0)								\



#define arch_mcs_spin_unlock_contended(lock)				\

#define arch_mcs_lock_handoff(lock, val)				\

do {									\

	smp_store_release(lock, 1);					\

	smp_store_release((lock), (val));				\

	dsb_sev();							\

} while (0)

include/asm-generic/mcs_spinlock.h

+2 −2
Original line number Diff line number Diff line
@@ -4,8 +4,8 @@ 
/*

 * Architectures can define their own:

 *

 *   arch_mcs_spin_lock_contended(l)

 *   arch_mcs_spin_unlock_contended(l)

 *   arch_mcs_spin_wait(l)

 *   arch_mcs_lock_handoff(l, val)

 *

 * See kernel/locking/mcs_spinlock.c.

 */

kernel/locking/mcs_spinlock.h

+9 −9
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ struct mcs_spinlock { 
	int count;  /* nesting count, see qspinlock.c */

};



#ifndef arch_mcs_spin_lock_contended

#ifndef arch_mcs_spin_wait

/*

 * Using smp_cond_load_acquire() provides the acquire semantics

 * required so that subsequent operations happen after the
@@ -29,20 +29,20 @@ struct mcs_spinlock { 
 * ARM64 would like to do spin-waiting instead of purely

 * spinning, and smp_cond_load_acquire() provides that behavior.

 */

#define arch_mcs_spin_lock_contended(l)					\

#define arch_mcs_spin_wait(l)					\

do {								\

	smp_cond_load_acquire(l, VAL);				\

} while (0)

#endif



#ifndef arch_mcs_spin_unlock_contended

#ifndef arch_mcs_lock_handoff

/*

 * smp_store_release() provides a memory barrier to ensure all

 * operations in the critical section has been completed before

 * unlocking.

 */

#define arch_mcs_spin_unlock_contended(l)				\

	smp_store_release((l), 1)

#define arch_mcs_lock_handoff(l, val)				\

	smp_store_release((l), (val))

#endif



/*
@@ -91,7 +91,7 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node) 
	WRITE_ONCE(prev->next, node);



	/* Wait until the lock holder passes the lock down. */

	arch_mcs_spin_lock_contended(&node->locked);

	arch_mcs_spin_wait(&node->locked);

}



/*
@@ -115,7 +115,7 @@ void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node) 
	}



	/* Pass lock to next waiter. */

	arch_mcs_spin_unlock_contended(&next->locked);

	arch_mcs_lock_handoff(&next->locked, 1);

}



#endif /* __LINUX_MCS_SPINLOCK_H */

kernel/locking/qspinlock.c

+2 −2
Original line number Diff line number Diff line
@@ -474,7 +474,7 @@ void __lockfunc queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) 
		WRITE_ONCE(prev->next, node);



		pv_wait_node(node, prev);

		arch_mcs_spin_lock_contended(&node->locked);

		arch_mcs_spin_wait(&node->locked);



		/*

		 * While waiting for the MCS lock, the next pointer may have
@@ -553,7 +553,7 @@ void __lockfunc queued_spin_lock_slowpath(struct qspinlock *lock, u32 val) 
	if (!next)

		next = smp_cond_load_relaxed(&node->next, (VAL));



	arch_mcs_spin_unlock_contended(&next->locked);

	arch_mcs_lock_handoff(&next->locked, 1);

	pv_kick_node(lock, next);



release:

kernel/locking/qspinlock_paravirt.h

+1 −1
Original line number Diff line number Diff line
@@ -368,7 +368,7 @@ static void pv_kick_node(struct qspinlock *lock, struct mcs_spinlock *node) 
	 *

	 * Matches with smp_store_mb() and cmpxchg() in pv_wait_node()

	 *

	 * The write to next->locked in arch_mcs_spin_unlock_contended()

	 * The write to next->locked in arch_mcs_lock_handoff()

	 * must be ordered before the read of pn->state in the cmpxchg()

	 * below for the code to work correctly. To guarantee full ordering

	 * irrespective of the success or failure of the cmpxchg(),