Commit cd21067f authored by Petr Mladek's avatar Petr Mladek Committed by Steven Rostedt
Browse files

ftrace: Warn on error when modifying ftrace function 

We should print some warning and kill ftrace functionality when the ftrace
function is not set correctly. Otherwise, ftrace might do crazy things without
an explanation. The error value has been ignored so far.

Note that an error that happens during updating all the traced calls is handled
in ftrace_replace_code(). We print more details about the particular
failing address via ftrace_bug() there.

Link: http://lkml.kernel.org/r/1393258342-29978-3-git-send-email-pmladek@suse.cz



Signed-off-by: default avatarPetr Mladek <pmladek@suse.cz>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent a762782d

kernel/trace/ftrace.c

+12 −5
Original line number Diff line number Diff line
@@ -1994,6 +1994,7 @@ int __weak ftrace_arch_code_modify_post_process(void) 
void ftrace_modify_all_code(int command)

{

	int update = command & FTRACE_UPDATE_TRACE_FUNC;

	int err = 0;



	/*

	 * If the ftrace_caller calls a ftrace_ops func directly,
@@ -2005,8 +2006,11 @@ void ftrace_modify_all_code(int command) 
	 * to make sure the ops are having the right functions

	 * traced.

	 */

	if (update)

		ftrace_update_ftrace_func(ftrace_ops_list_func);

	if (update) {

		err = ftrace_update_ftrace_func(ftrace_ops_list_func);

		if (FTRACE_WARN_ON(err))

			return;

	}



	if (command & FTRACE_UPDATE_CALLS)

		ftrace_replace_code(1);
@@ -2019,13 +2023,16 @@ void ftrace_modify_all_code(int command) 
		/* If irqs are disabled, we are in stop machine */

		if (!irqs_disabled())

			smp_call_function(ftrace_sync_ipi, NULL, 1);

		ftrace_update_ftrace_func(ftrace_trace_function);

		err = ftrace_update_ftrace_func(ftrace_trace_function);

		if (FTRACE_WARN_ON(err))

			return;

	}



	if (command & FTRACE_START_FUNC_RET)

		ftrace_enable_ftrace_graph_caller();

		err = ftrace_enable_ftrace_graph_caller();

	else if (command & FTRACE_STOP_FUNC_RET)

		ftrace_disable_ftrace_graph_caller();

		err = ftrace_disable_ftrace_graph_caller();

	FTRACE_WARN_ON(err);

}



static int __ftrace_modify_code(void *data)

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