From: "Steven Rostedt (Red Hat)" Instead of using the generic list function for callbacks that are not recursive, call a new helper function from the mcount trampoline called ftrace_ops_recur_func() that will do the recursion checking for the callback. This eliminates an indirection as well as will help in future code that will use dynamically allocated trampolines. Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 5916a8e59e87..17b606362ab4 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -113,6 +113,9 @@ ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub; static struct ftrace_ops global_ops; static struct ftrace_ops control_ops; +static void ftrace_ops_recurs_func(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, struct pt_regs *regs); + #if ARCH_SUPPORTS_FTRACE_OPS static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct pt_regs *regs); @@ -258,11 +261,18 @@ static void update_ftrace_function(void) if (ftrace_ops_list == &ftrace_list_end || (ftrace_ops_list->next == &ftrace_list_end && !(ftrace_ops_list->flags & FTRACE_OPS_FL_DYNAMIC) && - (ftrace_ops_list->flags & FTRACE_OPS_FL_RECURSION_SAFE) && !FTRACE_FORCE_LIST_FUNC)) { /* Set the ftrace_ops that the arch callback uses */ set_function_trace_op = ftrace_ops_list; - func = ftrace_ops_list->func; + /* + * If the func handles its own recursion, call it directly. + * Otherwise call the recursion protected function that + * will call the ftrace ops function. + */ + if (ftrace_ops_list->flags & FTRACE_OPS_FL_RECURSION_SAFE) + func = ftrace_ops_list->func; + else + func = ftrace_ops_recurs_func; } else { /* Just use the default ftrace_ops */ set_function_trace_op = &ftrace_list_end; @@ -4827,6 +4837,25 @@ static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip) } #endif +/* + * If there's only one function registered but it does not support + * recursion, this function will be called by the mcount trampoline. + * This function will handle recursion protection. + */ +static void ftrace_ops_recurs_func(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, struct pt_regs *regs) +{ + int bit; + + bit = trace_test_and_set_recursion(TRACE_LIST_START, TRACE_LIST_MAX); + if (bit < 0) + return; + + op->func(ip, parent_ip, op, regs); + + trace_clear_recursion(bit); +} + static void clear_ftrace_swapper(void) { struct task_struct *p; -- 2.0.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/