Commit 13b9a962 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

locking/rwsem: Rename 'activity' to 'count' 



There are two definitions of struct rw_semaphore, one in linux/rwsem.h
and one in linux/rwsem-spinlock.h.

For some reason they have different names for the initial field. This
makes it impossible to use C99 named initialization for
__RWSEM_INITIALIZER() -- or we have to duplicate that entire thing
along with the structure definitions.

The simpler patch is renaming the rwsem-spinlock variant to match the
regular rwsem.

This allows us to switch to C99 named initialization.

Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-bmrZolsbGmautmzrerog27io@git.kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 33ecd208

include/linux/rwsem-spinlock.h

+4 −4
Original line number Diff line number Diff line
@@ -15,13 +15,13 @@ 
#ifdef __KERNEL__

/*

 * the rw-semaphore definition

 * - if activity is 0 then there are no active readers or writers

 * - if activity is +ve then that is the number of active readers

 * - if activity is -1 then there is one active writer

 * - if count is 0 then there are no active readers or writers

 * - if count is +ve then that is the number of active readers

 * - if count is -1 then there is one active writer

 * - if wait_list is not empty, then there are processes waiting for the semaphore

 */

struct rw_semaphore {

	__s32			activity;

	__s32			count;

	raw_spinlock_t		wait_lock;

	struct list_head	wait_list;

#ifdef CONFIG_DEBUG_LOCK_ALLOC

kernel/locking/rwsem-spinlock.c

+14 −14
Original line number Diff line number Diff line
@@ -26,7 +26,7 @@ int rwsem_is_locked(struct rw_semaphore *sem) 
	unsigned long flags;



	if (raw_spin_trylock_irqsave(&sem->wait_lock, flags)) {

		ret = (sem->activity != 0);

		ret = (sem->count != 0);

		raw_spin_unlock_irqrestore(&sem->wait_lock, flags);

	}

	return ret;
@@ -46,7 +46,7 @@ void __init_rwsem(struct rw_semaphore *sem, const char *name, 
	debug_check_no_locks_freed((void *)sem, sizeof(*sem));

	lockdep_init_map(&sem->dep_map, name, key, 0);

#endif

	sem->activity = 0;

	sem->count = 0;

	raw_spin_lock_init(&sem->wait_lock);

	INIT_LIST_HEAD(&sem->wait_list);

}
@@ -95,7 +95,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wakewrite) 
		waiter = list_entry(next, struct rwsem_waiter, list);

	} while (waiter->type != RWSEM_WAITING_FOR_WRITE);



	sem->activity += woken;

	sem->count += woken;



 out:

	return sem;
@@ -126,9 +126,9 @@ void __sched __down_read(struct rw_semaphore *sem) 


	raw_spin_lock_irqsave(&sem->wait_lock, flags);



	if (sem->activity >= 0 && list_empty(&sem->wait_list)) {

	if (sem->count >= 0 && list_empty(&sem->wait_list)) {

		/* granted */

		sem->activity++;

		sem->count++;

		raw_spin_unlock_irqrestore(&sem->wait_lock, flags);

		goto out;

	}
@@ -170,9 +170,9 @@ int __down_read_trylock(struct rw_semaphore *sem) 


	raw_spin_lock_irqsave(&sem->wait_lock, flags);



	if (sem->activity >= 0 && list_empty(&sem->wait_list)) {

	if (sem->count >= 0 && list_empty(&sem->wait_list)) {

		/* granted */

		sem->activity++;

		sem->count++;

		ret = 1;

	}
@@ -206,7 +206,7 @@ void __sched __down_write_nested(struct rw_semaphore *sem, int subclass) 
		 * itself into sleep and waiting for system woke it or someone

		 * else in the head of the wait list up.

		 */

		if (sem->activity == 0)

		if (sem->count == 0)

			break;

		set_task_state(tsk, TASK_UNINTERRUPTIBLE);

		raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
@@ -214,7 +214,7 @@ void __sched __down_write_nested(struct rw_semaphore *sem, int subclass) 
		raw_spin_lock_irqsave(&sem->wait_lock, flags);

	}

	/* got the lock */

	sem->activity = -1;

	sem->count = -1;

	list_del(&waiter.list);



	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
@@ -235,9 +235,9 @@ int __down_write_trylock(struct rw_semaphore *sem) 


	raw_spin_lock_irqsave(&sem->wait_lock, flags);



	if (sem->activity == 0) {

	if (sem->count == 0) {

		/* got the lock */

		sem->activity = -1;

		sem->count = -1;

		ret = 1;

	}
@@ -255,7 +255,7 @@ void __up_read(struct rw_semaphore *sem) 


	raw_spin_lock_irqsave(&sem->wait_lock, flags);



	if (--sem->activity == 0 && !list_empty(&sem->wait_list))

	if (--sem->count == 0 && !list_empty(&sem->wait_list))

		sem = __rwsem_wake_one_writer(sem);



	raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
@@ -270,7 +270,7 @@ void __up_write(struct rw_semaphore *sem) 


	raw_spin_lock_irqsave(&sem->wait_lock, flags);



	sem->activity = 0;

	sem->count = 0;

	if (!list_empty(&sem->wait_list))

		sem = __rwsem_do_wake(sem, 1);
@@ -287,7 +287,7 @@ void __downgrade_write(struct rw_semaphore *sem) 


	raw_spin_lock_irqsave(&sem->wait_lock, flags);



	sem->activity = 1;

	sem->count = 1;

	if (!list_empty(&sem->wait_list))

		sem = __rwsem_do_wake(sem, 0);

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