Commit 2a7b8df0 authored Feb 12, 2009 by Steven Rostedt

sched: do not account for NMIs



Impact: avoid corruption in system time accounting

Martin Schwidefsky told me that there was an issue with NMIs and
system accounting. The problem is that the accounting code is
not reentrant, and if an NMI goes off after an interrupt it can
corrupt the accounting.

For now, the best we can do is to treat NMIs like SMIs and they
are not accounted for.

This patch changes nmi_enter to not call __irq_enter and to do
the preempt-count and tracing calls directly.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

parent 5a5fb7db

include/linux/hardirq.h

+16 −16

Original line number	Diff line number	Diff line
		@@ -179,19 +179,19 @@ extern void irq_exit(void);
		do { \
		ftrace_nmi_enter(); \
		BUG_ON(in_nmi()); \
		add_preempt_count(NMI_OFFSET); \
		add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
		lockdep_off(); \
		rcu_nmi_enter(); \
		__irq_enter(); \
		trace_hardirq_enter(); \
		} while (0)

		#define nmi_exit() \
		do { \
		__irq_exit(); \
		trace_hardirq_exit(); \
		rcu_nmi_exit(); \
		lockdep_on(); \
		BUG_ON(!in_nmi()); \
		sub_preempt_count(NMI_OFFSET); \
		sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET); \
		ftrace_nmi_exit(); \
		} while (0)

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