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/* Copyright 2013-2014 IBM Corp.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef __LOCK_H
#define __LOCK_H
#include <stdbool.h>
struct lock {
/* Lock value has bit 63 as lock bit and the PIR of the owner
* in the top 32-bit
*/
unsigned long lock_val;
/*
* Set to true if lock is involved in the console flush path
* in which case taking it will suspend console flushing
*/
bool in_con_path;
};
/* Initializer */
#define LOCK_UNLOCKED { .lock_val = 0, .in_con_path = 0 }
/* Note vs. libc and locking:
*
* The printf() family of
* functions use stack based t buffers and call into skiboot
* underlying read() and write() which use a console lock.
*
* The underlying FSP console code will thus operate within that
* console lock.
*
* The libc does *NOT* lock stream buffer operations, so don't
* try to scanf() from the same FILE from two different processors.
*
* FSP operations are locked using an FSP lock, so all processors
* can safely call the FSP API
*
* Note about ordering:
*
* lock() is a full memory barrier. unlock() is a lwsync
*
*/
extern bool bust_locks;
static inline void init_lock(struct lock *l)
{
l->lock_val = 0;
l->in_con_path = false;
}
extern bool __try_lock(struct lock *l);
extern bool try_lock(struct lock *l);
extern void lock(struct lock *l);
extern void unlock(struct lock *l);
/* The debug output can happen while the FSP lock, so we need some kind
* of recursive lock support here. I don't want all locks to be recursive
* though, thus the caller need to explicitly call lock_recursive which
* returns false if the lock was already held by this cpu. If it returns
* true, then the caller shall release it when done.
*/
extern bool lock_recursive(struct lock *l);
/* Called after per-cpu data structures are available */
extern void init_locks(void);
#endif /* __LOCK_H */
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