From 0daa2302968c13b657118d6ac92471f8fd2f3f28 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Fri, 12 Dec 2014 22:27:10 -0500 Subject: tracing: Add tp_printk cmdline to have tracepoints go to printk() Add the kernel command line tp_printk option that will have tracepoints that are active sent to printk() as well as to the trace buffer. Passing "tp_printk" will activate this. To turn it off, the sysctl /proc/sys/kernel/tracepoint_printk can have '0' echoed into it. Note, this only works if the cmdline option is used. Echoing 1 into the sysctl file without the cmdline option will have no affect. Note, this is a dangerous option. Having high frequency tracepoints send their data to printk() can possibly cause a live lock. This is another reason why this is only active if the command line option is used. Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412121539300.16494@nanos Suggested-by: Thomas Gleixner Tested-by: Thomas Gleixner Acked-by: Thomas Gleixner Signed-off-by: Steven Rostedt --- include/linux/ftrace.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/ftrace.h') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index f4bc14b7d444..1da602982cf9 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -879,6 +879,7 @@ static inline int test_tsk_trace_graph(struct task_struct *tsk) enum ftrace_dump_mode; extern enum ftrace_dump_mode ftrace_dump_on_oops; +extern int tracepoint_printk; extern void disable_trace_on_warning(void); extern int __disable_trace_on_warning; -- cgit