extern struct lttng_trace_clock *lttng_trace_clock;
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0))
+/*
+ * Upstream Linux commit 27727df240c7 ("Avoid taking lock in NMI path with
+ * CONFIG_DEBUG_TIMEKEEPING") introduces a buggy ktime_get_mono_fast_ns().
+ * This is fixed by patch "timekeeping: Fix __ktime_get_fast_ns() regression".
+ */
+#if (LTTNG_KERNEL_RANGE(4,8,0, 4,8,2) \
+ || LTTNG_KERNEL_RANGE(4,7,4, 4,7,8) \
+ || LTTNG_KERNEL_RANGE(4,4,20, 4,4,25) \
+ || LTTNG_KERNEL_RANGE(4,1,32, 4,1,35))
+#define LTTNG_CLOCK_NMI_SAFE_BROKEN
+#endif
+
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0) \
+ && !defined(LTTNG_CLOCK_NMI_SAFE_BROKEN))
DECLARE_PER_CPU(local_t, lttng_last_tsc);
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0))
static inline int get_trace_clock(void)
{
- printk(KERN_WARNING "LTTng: Using mainline kernel monotonic fast clock, which is NMI-safe.\n");
+ printk_once(KERN_WARNING "LTTng: Using mainline kernel monotonic fast clock, which is NMI-safe.\n");
return 0;
}
#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)) */
static inline int get_trace_clock(void)
{
- printk(KERN_WARNING "LTTng: Using mainline kernel monotonic clock. NMIs will not be traced.\n");
+ printk_once(KERN_WARNING "LTTng: Using mainline kernel monotonic clock. NMIs will not be traced.\n");
return 0;
}
#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)) */