[PATCH] NMI: Update NMI users of RCU to use new API
Uses of RCU for dynamically changeable NMI handlers need to use the new
rcu_dereference() and rcu_assign_pointer() facilities. This change makes
it clear that these uses are safe from a memory-barrier viewpoint, but the
main purpose is to document exactly what operations are being protected by
RCU. This has been tested on x86 and x86-64, which are the only
architectures affected by this change.
Signed-off-by: <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/x86_64/kernel/nmi.c b/arch/x86_64/kernel/nmi.c
index 84cae81..caf1649 100644
--- a/arch/x86_64/kernel/nmi.c
+++ b/arch/x86_64/kernel/nmi.c
@@ -524,14 +524,14 @@
nmi_enter();
add_pda(__nmi_count,1);
- if (!nmi_callback(regs, cpu))
+ if (!rcu_dereference(nmi_callback)(regs, cpu))
default_do_nmi(regs);
nmi_exit();
}
void set_nmi_callback(nmi_callback_t callback)
{
- nmi_callback = callback;
+ rcu_assign_pointer(nmi_callback, callback);
}
void unset_nmi_callback(void)