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[PATCH] Deprecate synchronize_kernel, GPL replacement

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The synchronize_kernel() primitive is used for quite a few different purposes:
waiting for RCU readers, waiting for NMIs, waiting for interrupts, and so on.
This makes RCU code harder to read, since synchronize_kernel() might or might
not have matching rcu_read_lock()s.  This patch creates a new
synchronize_rcu() that is to be used for RCU readers and a new
synchronize_sched() that is used for the rest.  These two new primitives
currently have the same implementation, but this is might well change with
additional real-time support.  Both new primitives are GPL-only, the old
primitive is deprecated.

Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Paul E. McKenney
2005-05-01 08:59:04 -07:00
committed by Linus Torvalds
parent 512345be25
commit 9b06e81898
2 changed files with 34 additions and 5 deletions
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16
kernel/rcupdate.c
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@ -444,15 +444,18 @@ static void wakeme_after_rcu(struct rcu_head *head)
}
/**
* synchronize_kernel - wait until a grace period has elapsed.
* synchronize_rcu - wait until a grace period has elapsed.
*
* Control will return to the caller some time after a full grace
* period has elapsed, in other words after all currently executing RCU
* read-side critical sections have completed. RCU read-side critical
* sections are delimited by rcu_read_lock() and rcu_read_unlock(),
* and may be nested.
*
* If your read-side code is not protected by rcu_read_lock(), do -not-
* use synchronize_rcu().
*/
void synchronize_kernel(void)
void synchronize_rcu(void)
{
struct rcu_synchronize rcu;
@ -464,7 +467,16 @@ void synchronize_kernel(void)
wait_for_completion(&rcu.completion);
}
/*
* Deprecated, use synchronize_rcu() or synchronize_sched() instead.
*/
void synchronize_kernel(void)
{
synchronize_rcu();
}
module_param(maxbatch, int, 0);
EXPORT_SYMBOL(call_rcu); /* WARNING: GPL-only in April 2006. */
EXPORT_SYMBOL(call_rcu_bh); /* WARNING: GPL-only in April 2006. */
EXPORT_SYMBOL_GPL(synchronize_rcu);
EXPORT_SYMBOL(synchronize_kernel); /* WARNING: GPL-only in April 2006. */