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ftrace: Add enable/disable ftrace_ops control interface

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Adding a way to temporarily enable/disable ftrace_ops. The change
follows the same way as 'global' ftrace_ops are done.

Introducing 2 global ftrace_ops - control_ops and ftrace_control_list
which take over all ftrace_ops registered with FTRACE_OPS_FL_CONTROL
flag. In addition new per cpu flag called 'disabled' is also added to
ftrace_ops to provide the control information for each cpu.

When ftrace_ops with FTRACE_OPS_FL_CONTROL is registered, it is
set as disabled for all cpus.

The ftrace_control_list contains all the registered 'control' ftrace_ops.
The control_ops provides function which iterates ftrace_control_list
and does the check for 'disabled' flag on current cpu.

Adding 3 inline functions:
  ftrace_function_local_disable/ftrace_function_local_enable
  - enable/disable the ftrace_ops on current cpu
  ftrace_function_local_disabled
  - get disabled ftrace_ops::disabled value for current cpu

Link: http://lkml.kernel.org/r/1329317514-8131-2-git-send-email-jolsa@redhat.com

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Jiri Olsa
2012-02-15 15:51:48 +01:00
committed by Steven Rostedt
parent 5b34926114
commit e248491ac2
3 changed files with 172 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

111
kernel/trace/ftrace.c
View File

@@ -62,6 +62,8 @@
#define FTRACE_HASH_DEFAULT_BITS 10
#define FTRACE_HASH_MAX_BITS 12
#define FL_GLOBAL_CONTROL_MASK (FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_CONTROL)
/* ftrace_enabled is a method to turn ftrace on or off */
int ftrace_enabled __read_mostly;
static int last_ftrace_enabled;
@@ -89,12 +91,14 @@ static struct ftrace_ops ftrace_list_end __read_mostly = {
};
static struct ftrace_ops *ftrace_global_list __read_mostly = &ftrace_list_end;
static struct ftrace_ops *ftrace_control_list __read_mostly = &ftrace_list_end;
static struct ftrace_ops *ftrace_ops_list __read_mostly = &ftrace_list_end;
ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
static ftrace_func_t __ftrace_trace_function_delay __read_mostly = ftrace_stub;
ftrace_func_t __ftrace_trace_function __read_mostly = ftrace_stub;
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_list_func(unsigned long ip, unsigned long parent_ip);
@@ -168,6 +172,32 @@ static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)
}
#endif
static void control_ops_disable_all(struct ftrace_ops *ops)
{
int cpu;
for_each_possible_cpu(cpu)
*per_cpu_ptr(ops->disabled, cpu) = 1;
}
static int control_ops_alloc(struct ftrace_ops *ops)
{
int __percpu *disabled;
disabled = alloc_percpu(int);
if (!disabled)
return -ENOMEM;
ops->disabled = disabled;
control_ops_disable_all(ops);
return 0;
}
static void control_ops_free(struct ftrace_ops *ops)
{
free_percpu(ops->disabled);
}
static void update_global_ops(void)
{
ftrace_func_t func;
@@ -259,6 +289,26 @@ static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
return 0;
}
static void add_ftrace_list_ops(struct ftrace_ops **list,
struct ftrace_ops *main_ops,
struct ftrace_ops *ops)
{
int first = *list == &ftrace_list_end;
add_ftrace_ops(list, ops);
if (first)
add_ftrace_ops(&ftrace_ops_list, main_ops);
}
static int remove_ftrace_list_ops(struct ftrace_ops **list,
struct ftrace_ops *main_ops,
struct ftrace_ops *ops)
{
int ret = remove_ftrace_ops(list, ops);
if (!ret && *list == &ftrace_list_end)
ret = remove_ftrace_ops(&ftrace_ops_list, main_ops);
return ret;
}
static int __register_ftrace_function(struct ftrace_ops *ops)
{
if (ftrace_disabled)
@@ -270,15 +320,20 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
if (WARN_ON(ops->flags & FTRACE_OPS_FL_ENABLED))
return -EBUSY;
/* We don't support both control and global flags set. */
if ((ops->flags & FL_GLOBAL_CONTROL_MASK) == FL_GLOBAL_CONTROL_MASK)
return -EINVAL;
if (!core_kernel_data((unsigned long)ops))
ops->flags |= FTRACE_OPS_FL_DYNAMIC;
if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
int first = ftrace_global_list == &ftrace_list_end;
add_ftrace_ops(&ftrace_global_list, ops);
add_ftrace_list_ops(&ftrace_global_list, &global_ops, ops);
ops->flags |= FTRACE_OPS_FL_ENABLED;
if (first)
add_ftrace_ops(&ftrace_ops_list, &global_ops);
} else if (ops->flags & FTRACE_OPS_FL_CONTROL) {
if (control_ops_alloc(ops))
return -ENOMEM;
add_ftrace_list_ops(&ftrace_control_list, &control_ops, ops);
} else
add_ftrace_ops(&ftrace_ops_list, ops);
@@ -302,11 +357,23 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops)
return -EINVAL;
if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
ret = remove_ftrace_ops(&ftrace_global_list, ops);
if (!ret && ftrace_global_list == &ftrace_list_end)
ret = remove_ftrace_ops(&ftrace_ops_list, &global_ops);
ret = remove_ftrace_list_ops(&ftrace_global_list,
&global_ops, ops);
if (!ret)
ops->flags &= ~FTRACE_OPS_FL_ENABLED;
} else if (ops->flags & FTRACE_OPS_FL_CONTROL) {
ret = remove_ftrace_list_ops(&ftrace_control_list,
&control_ops, ops);
if (!ret) {
/*
* The ftrace_ops is now removed from the list,
* so there'll be no new users. We must ensure
* all current users are done before we free
* the control data.
*/
synchronize_sched();
control_ops_free(ops);
}
} else
ret = remove_ftrace_ops(&ftrace_ops_list, ops);
@@ -3873,6 +3940,36 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
#endif /* CONFIG_DYNAMIC_FTRACE */
static void
ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip)
{
struct ftrace_ops *op;
if (unlikely(trace_recursion_test(TRACE_CONTROL_BIT)))
return;
/*
* Some of the ops may be dynamically allocated,
* they must be freed after a synchronize_sched().
*/
preempt_disable_notrace();
trace_recursion_set(TRACE_CONTROL_BIT);
op = rcu_dereference_raw(ftrace_control_list);
while (op != &ftrace_list_end) {
if (!ftrace_function_local_disabled(op) &&
ftrace_ops_test(op, ip))
op->func(ip, parent_ip);
op = rcu_dereference_raw(op->next);
};
trace_recursion_clear(TRACE_CONTROL_BIT);
preempt_enable_notrace();
}
static struct ftrace_ops control_ops = {
.func = ftrace_ops_control_func,
};
static void
ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
{