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Commit 69bb54ec authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

ftrace: add ftrace_off_permanent 



Impact: add new API to disable all of ftrace on anomalies

It case of a serious anomaly being detected (like something caught by
lockdep) it is a good idea to disable all tracing immediately, without
grabing any locks.

This patch adds ftrace_off_permanent that disables the tracers, function
tracing and ring buffers without a way to enable them again. This should
only be used when something serious has been detected.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e58918ab

include/linux/ftrace.h

+2 −0
Original line number Diff line number Diff line
@@ -257,6 +257,7 @@ extern int ftrace_dump_on_oops; 


extern void tracing_start(void);

extern void tracing_stop(void);

extern void ftrace_off_permanent(void);



extern void

ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3);
@@ -290,6 +291,7 @@ ftrace_printk(const char *fmt, ...) __attribute__ ((format (printf, 1, 0))); 


static inline void tracing_start(void) { }

static inline void tracing_stop(void) { }

static inline void ftrace_off_permanent(void) { }

static inline int

ftrace_printk(const char *fmt, ...)

{

kernel/trace/trace.c

+15 −0
Original line number Diff line number Diff line
@@ -660,6 +660,21 @@ static void trace_init_cmdlines(void) 
static int trace_stop_count;

static DEFINE_SPINLOCK(tracing_start_lock);



/**

 * ftrace_off_permanent - disable all ftrace code permanently

 *

 * This should only be called when a serious anomally has

 * been detected.  This will turn off the function tracing,

 * ring buffers, and other tracing utilites. It takes no

 * locks and can be called from any context.

 */

void ftrace_off_permanent(void)

{

	tracing_disabled = 1;

	ftrace_stop();

	tracing_off_permanent();

}



/**

 * tracing_start - quick start of the tracer

 *