path: root/kernel/rcupdate.c
diff options
authorPaul E. McKenney <paulmck@us.ibm.com>2005-05-01 08:59:04 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-05-01 08:59:04 -0700
commit9b06e818985d139fd9e82c28297f7744e1b484e1 (patch)
tree3cd2ba33b22fc2812f714f86ea52c68704f8e2c3 /kernel/rcupdate.c
parent512345be2549308b8ae8e85a3ff7f6d56a38e5f6 (diff)
[PATCH] Deprecate synchronize_kernel, GPL replacement
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>
Diffstat (limited to 'kernel/rcupdate.c')
1 files changed, 14 insertions, 2 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index ad497722f04f..f436993bd590 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -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)
+ * 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(synchronize_kernel); /* WARNING: GPL-only in April 2006. */

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