include/litmus/locking.h


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#ifndef LITMUS_LOCKING_H
#define LITMUS_LOCKING_H

#include <linux/list.h>

struct litmus_lock_ops;

/* Generic base struct for LITMUS^RT userspace semaphores.
 * This structure should be embedded in protocol-specific semaphores.
 */
struct litmus_lock {
	struct litmus_lock_ops *ops;
	int type;
    
#ifdef CONFIG_LITMUS_NESTED_LOCKING
    struct list_head lock_chain;
#endif
};

struct litmus_lock_ops {
	/* Current task tries to obtain / drop a reference to a lock.
	 * Optional methods, allowed by default. */
	int (*open)(struct litmus_lock*, void* __user);
	int (*close)(struct litmus_lock*);

	/* Current tries to lock/unlock this lock (mandatory methods). */
	int (*lock)(struct litmus_lock*);
	int (*unlock)(struct litmus_lock*);

	/* The lock is no longer being referenced (mandatory method). */
	void (*deallocate)(struct litmus_lock*);
};

#endif