From 2002c258faaa8f89543df284fdbaa9e4b171547f Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 5 Mar 2009 10:35:56 -0500 Subject: tracing: add tracing_on/tracing_off to kernel.h Impact: cleanup The functions tracing_start/tracing_stop have been moved to kernel.h. These are not the functions a developer most likely wants to use when they want to insert a place to stop tracing and restart it from user space. tracing_start/tracing_stop was created to work with things like suspend to ram, where even calling smp_processor_id() can crash the system. The tracing_start/tracing_stop was used to stop the tracer from doing anything. These are still light weight functions, but add a bit more overhead to be able to stop the tracers. They also have no interface back to userland. That is, if the kernel calls tracing_stop, userland can not start tracing. What a developer most likely wants to use is tracing_on/tracing_off. These are very light weight functions (simply sets or clears a bit). These functions just stop recording into the ring buffer. The tracers don't even know that this happens except that they would receive NULL from the ring_buffer_lock_reserve function. Also, there's a way for the user land to enable or disable this bit. In debugfs/tracing/tracing_on, a user may echo "0" (same as tracing_off()) or echo "1" (same as tracing_on()) into this file. This becomes handy when a kernel developer is debugging and wants tracing to turn off when it hits an anomaly. Then the developer can examine the trace, and restart tracing if they want to try again (echo 1 > tracing_on). This patch moves the prototypes for tracing_on/tracing_off to kernel.h and comments their use, so that a kernel developer will know how to use them. Signed-off-by: Steven Rostedt --- include/linux/ring_buffer.h | 15 --------------- 1 file changed, 15 deletions(-) (limited to 'include/linux/ring_buffer.h') diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 79fcbc4b09d..b1a0068a555 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -124,21 +124,6 @@ void ring_buffer_normalize_time_stamp(int cpu, u64 *ts); size_t ring_buffer_page_len(void *page); -/* - * The below functions are fine to use outside the tracing facility. - */ -#ifdef CONFIG_RING_BUFFER -void tracing_on(void); -void tracing_off(void); -void tracing_off_permanent(void); -int tracing_is_on(void); -#else -static inline void tracing_on(void) { } -static inline void tracing_off(void) { } -static inline void tracing_off_permanent(void) { } -static inline int tracing_is_on(void) { return 0; } -#endif - void *ring_buffer_alloc_read_page(struct ring_buffer *buffer); void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data); int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page, -- cgit v1.2.3-70-g09d2