Re: [openib-general] Re: [PATCH][RFC/v1][4/12] Add InfiniBand SA (Subnet Administration) query support

[Roland Dreier <roland@topspin.com>]

    Greg> No.  RCU is covered by a patent that only allows for it to
    Greg> be implemented in GPL licensed code.  If you want to use RCU
    Greg> in non-GPL code, you need to sign a license agreement with
    Greg> the holder of the RCU patent.

Not to stir up the flames any further (and this is really a moot point
since I got rid of our use of RCU)...

But given that I could implement the same API as in rcupdate.h as
below without using IBM's patented technique, how does merely using
this API cause code to require a patent license?

Thanks,
 Roland

/*
 * Copyright (c) 2004 Topspin Communications.  All rights reserved.
 * 
 * Usage of the works is permitted provided that this instrument is
 * retained with the works, so that any entity that uses the works is
 * notified of this instrument.
 *
 * DISCLAIMER: THE WORKS ARE WITHOUT WARRANTY.
 */

#ifndef MYRCU_H
#define MYRCU_H

struct rcu_head { };

#define rcu_read_lock		lock_kernel()
#define rcu_read_unlock		unlock_kernel()

#define rcu_dereference(p)	(p)
#define rcu_assign_pointer(p,v)	do { \
	lock_kernel(); \
	(p) = (v); \
	unlock_kernel(); \
} while (0)

static inline void call_rcu(struct rcu_head *head,
			    void (*func)(struct rcu_head *head))
{
	lock_kernel();
	func(head);
	unlock_kernel();
}

#endif /* MYRCU_H */