Commit 486fbcb3 authored by Masami Hiramatsu (Google)'s avatar Masami Hiramatsu (Google) Committed by Steven Rostedt (Google)
Browse files

tracing: Skip update_last_data() if cleared and remove active check for save_mod() 

If the last boot data is already cleared, there is no reason to update it
again. Skip if the TRACE_ARRAY_FL_LAST_BOOT is cleared.
Also, for calling save_mod() when module loading, we don't need to check
the trace is active or not because any module address can be on the
stacktrace.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/174165660328.1173316.15529357882704817499.stgit@devnote2


Signed-off-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 5dbeb56b

kernel/trace/trace.c

+8 −18
Original line number Diff line number Diff line
@@ -6040,6 +6040,12 @@ static void update_last_data(struct trace_array *tr) 
	if (!(tr->flags & TRACE_ARRAY_FL_BOOT))

		return;



	if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))

		return;



	/* Only if the buffer has previous boot data clear and update it. */

	tr->flags &= ~TRACE_ARRAY_FL_LAST_BOOT;



	/* Reset the module list and reload them */

	if (tr->scratch) {

		struct trace_scratch *tscratch = tr->scratch;
@@ -6052,9 +6058,6 @@ static void update_last_data(struct trace_array *tr) 
		module_for_each_mod(save_mod, tr);

	}



	if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))

		return;



	/*

	 * Need to clear all CPU buffers as there cannot be events

	 * from the previous boot mixed with events with this boot
@@ -6077,7 +6080,6 @@ static void update_last_data(struct trace_array *tr) 
#else

	tscratch->kaslr_addr = 0;

#endif

	tr->flags &= ~TRACE_ARRAY_FL_LAST_BOOT;

}



/**
@@ -10103,15 +10105,6 @@ static void trace_module_remove_evals(struct module *mod) 
static inline void trace_module_remove_evals(struct module *mod) { }

#endif /* CONFIG_TRACE_EVAL_MAP_FILE */



static bool trace_array_active(struct trace_array *tr)

{

	if (tr->current_trace != &nop_trace)

		return true;



	/* 0 is no events, 1 is all disabled */

	return trace_events_enabled(tr, NULL) > 1;

}



static void trace_module_record(struct module *mod)

{

	struct trace_array *tr;
@@ -10120,14 +10113,11 @@ static void trace_module_record(struct module *mod) 
		/* Update any persistent trace array that has already been started */

		if ((tr->flags & (TRACE_ARRAY_FL_BOOT | TRACE_ARRAY_FL_LAST_BOOT)) ==

		    TRACE_ARRAY_FL_BOOT) {

			/* Only update if the trace array is active */

			if (trace_array_active(tr)) {

			guard(mutex)(&scratch_mutex);

			save_mod(mod, tr);

		}

	}

}

}



static int trace_module_notify(struct notifier_block *self,

			       unsigned long val, void *data)