[PATCH 1/2] NMI: Update NMI users of RCU to use new API
From: Paul E. McKenney
Date: Mon Jul 11 2005 - 10:32:37 EST
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@xxxxxxxxxx>
---
i386/kernel/traps.c | 4 ++--
x86_64/kernel/nmi.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)
diff -urpN -X dontdiff linux-2.6.12-rc6/arch/i386/kernel/traps.c linux-2.6.12-rc6-NMIRCUfix/arch/i386/kernel/traps.c
--- linux-2.6.12-rc6/arch/i386/kernel/traps.c 2005-06-17 16:34:17.000000000 -0700
+++ linux-2.6.12-rc6-NMIRCUfix/arch/i386/kernel/traps.c 2005-07-01 15:16:24.000000000 -0700
@@ -626,7 +626,7 @@ fastcall void do_nmi(struct pt_regs * re
cpu = smp_processor_id();
++nmi_count(cpu);
- if (!nmi_callback(regs, cpu))
+ if (!rcu_dereference(nmi_callback)(regs, cpu))
default_do_nmi(regs);
nmi_exit();
@@ -634,7 +634,7 @@ fastcall void do_nmi(struct pt_regs * re
void set_nmi_callback(nmi_callback_t callback)
{
- nmi_callback = callback;
+ rcu_assign_pointer(nmi_callback, callback);
}
void unset_nmi_callback(void)
diff -urpN -X dontdiff linux-2.6.12-rc6/arch/x86_64/kernel/nmi.c linux-2.6.12-rc6-NMIRCUfix/arch/x86_64/kernel/nmi.c
--- linux-2.6.12-rc6/arch/x86_64/kernel/nmi.c 2005-06-17 16:34:24.000000000 -0700
+++ linux-2.6.12-rc6-NMIRCUfix/arch/x86_64/kernel/nmi.c 2005-07-01 15:15:21.000000000 -0700
@@ -522,14 +522,14 @@ asmlinkage void do_nmi(struct pt_regs *
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)
-
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