From: Steven Rostedt This code adds an in_nmi() macro that uses the current tasks preempt count to track when it is in NMI context. Other parts of the kernel can use this to determine if the context is in NMI context or not. This code was inspired by the -rt patch in_nmi version that was written by Peter Zijlstra, who borrowed that code from Mathieu Desnoyers. Reported-by: Andrew Morton Signed-off-by: Steven Rostedt --- include/linux/hardirq.h | 15 +++++++++++++++ 1 files changed, 15 insertions(+), 0 deletions(-) diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index f832883..f3cf86e 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -61,6 +61,12 @@ #error PREEMPT_ACTIVE is too low! #endif +#define NMI_OFFSET (PREEMPT_ACTIVE << 1) + +#if NMI_OFFSET >= 0x80000000 +#error PREEMPT_ACTIVE too high! +#endif + #define hardirq_count() (preempt_count() & HARDIRQ_MASK) #define softirq_count() (preempt_count() & SOFTIRQ_MASK) #define irq_count() (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK)) @@ -73,6 +79,11 @@ #define in_softirq() (softirq_count()) #define in_interrupt() (irq_count()) +/* + * Are we in NMI context? + */ +#define in_nmi() (preempt_count() & NMI_OFFSET) + #if defined(CONFIG_PREEMPT) # define PREEMPT_INATOMIC_BASE kernel_locked() # define PREEMPT_CHECK_OFFSET 1 @@ -167,6 +178,8 @@ extern void irq_exit(void); #define nmi_enter() \ do { \ ftrace_nmi_enter(); \ + BUG_ON(in_nmi()); \ + add_preempt_count(NMI_OFFSET); \ lockdep_off(); \ rcu_nmi_enter(); \ __irq_enter(); \ @@ -177,6 +190,8 @@ extern void irq_exit(void); __irq_exit(); \ rcu_nmi_exit(); \ lockdep_on(); \ + BUG_ON(!in_nmi()); \ + sub_preempt_count(NMI_OFFSET); \ ftrace_nmi_exit(); \ } while (0) -- 1.5.6.5 -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/