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ftrace: Add separate function for non recursive callbacks

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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 <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2014-07-22 20:16:57 -04:00 committed by Steven Rostedt
parent 2ce7598c9a
commit f1ff6348b3
1 changed files with 31 additions and 2 deletions
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33
kernel/trace/ftrace.c
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@ -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;