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Message-Id: <1323105776-26961-4-git-send-email-jolsa@redhat.com>
Date: Mon, 5 Dec 2011 18:22:49 +0100
From: Jiri Olsa <jolsa@...hat.com>
To: rostedt@...dmis.org, fweisbec@...il.com, mingo@...hat.com,
paulus@...ba.org, acme@...stprotocols.net, a.p.zijlstra@...llo.nl
Cc: linux-kernel@...r.kernel.org, aarapov@...hat.com,
Jiri Olsa <jolsa@...hat.com>
Subject: [PATCHv2 03/10] ftrace: Add enable/disable ftrace_ops control interface
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 2 inline functions enable_ftrace_function/disable_ftrace_function,
which enable/disable the ftrace_ops for current cpu.
Signed-off-by: Jiri Olsa <jolsa@...hat.com>
---
include/linux/ftrace.h | 14 ++++++
kernel/trace/ftrace.c | 115 +++++++++++++++++++++++++++++++++++++++++++-----
kernel/trace/trace.h | 2 +
3 files changed, 120 insertions(+), 11 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 26eafce..b223944 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -35,12 +35,14 @@ enum {
FTRACE_OPS_FL_ENABLED = 1 << 0,
FTRACE_OPS_FL_GLOBAL = 1 << 1,
FTRACE_OPS_FL_DYNAMIC = 1 << 2,
+ FTRACE_OPS_FL_CONTROL = 1 << 3,
};
struct ftrace_ops {
ftrace_func_t func;
struct ftrace_ops *next;
unsigned long flags;
+ void __percpu *disabled;
#ifdef CONFIG_DYNAMIC_FTRACE
struct ftrace_hash *notrace_hash;
struct ftrace_hash *filter_hash;
@@ -97,6 +99,18 @@ int register_ftrace_function(struct ftrace_ops *ops);
int unregister_ftrace_function(struct ftrace_ops *ops);
void clear_ftrace_function(void);
+static inline void enable_ftrace_function(struct ftrace_ops *ops)
+{
+ atomic_t *disabled = this_cpu_ptr(ops->disabled);
+ atomic_dec(disabled);
+}
+
+static inline void disable_ftrace_function(struct ftrace_ops *ops)
+{
+ atomic_t *disabled = this_cpu_ptr(ops->disabled);
+ atomic_inc(disabled);
+}
+
extern void ftrace_stub(unsigned long a0, unsigned long a1);
#else /* !CONFIG_FUNCTION_TRACER */
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index b79ab33..c2fa233 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -87,12 +87,14 @@ 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);
@@ -166,6 +168,38 @@ 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)
+ atomic_set(per_cpu_ptr(ops->disabled, cpu), 1);
+}
+
+static int control_ops_alloc(struct ftrace_ops *ops)
+{
+ atomic_t *disabled;
+
+ disabled = alloc_percpu(atomic_t);
+ 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 int control_ops_is_disabled(struct ftrace_ops *ops)
+{
+ atomic_t *disabled = this_cpu_ptr(ops->disabled);
+ return atomic_read(disabled);
+}
+
static void update_global_ops(void)
{
ftrace_func_t func;
@@ -221,7 +255,7 @@ static void update_ftrace_function(void)
#endif
}
-static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
+static void __add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
{
ops->next = *list;
/*
@@ -233,7 +267,7 @@ static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
rcu_assign_pointer(*list, ops);
}
-static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
+static int __remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
{
struct ftrace_ops **p;
@@ -257,6 +291,26 @@ static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
return 0;
}
+static void add_ftrace_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_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)
@@ -268,17 +322,23 @@ static int __register_ftrace_function(struct ftrace_ops *ops)
if (WARN_ON(ops->flags & FTRACE_OPS_FL_ENABLED))
return -EBUSY;
+#define FL_GLOBAL_CONTROL (FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_CONTROL)
+ if ((ops->flags & FL_GLOBAL_CONTROL) == FL_GLOBAL_CONTROL)
+ return -EINVAL;
+#undef FL_GLOBAL_CONTROL
+
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_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_ops(&ftrace_control_list, &control_ops, ops);
} else
- add_ftrace_ops(&ftrace_ops_list, ops);
+ __add_ftrace_ops(&ftrace_ops_list, ops);
if (ftrace_enabled)
update_ftrace_function();
@@ -300,13 +360,16 @@ 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_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_ops(&ftrace_control_list,
+ &control_ops, ops);
+ if (!ret)
+ control_ops_free(ops);
} else
- ret = remove_ftrace_ops(&ftrace_ops_list, ops);
+ ret = __remove_ftrace_ops(&ftrace_ops_list, ops);
if (ret < 0)
return ret;
@@ -3562,6 +3625,36 @@ 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 (!control_ops_is_disabled(op) &&
+ ftrace_ops_test(op, ip))
+ op->func(ip, parent_ip);
+
+ op = rcu_dereference_raw(op->next);
+ };
+ preempt_enable_notrace();
+ trace_recursion_clear(TRACE_CONTROL_BIT);
+}
+
+static struct ftrace_ops control_ops = {
+ .func = ftrace_ops_control_func,
+};
+
+static void
ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
{
struct ftrace_ops *op;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index f8ec229..da05926 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -288,6 +288,8 @@ struct tracer {
/* for function tracing recursion */
#define TRACE_INTERNAL_BIT (1<<11)
#define TRACE_GLOBAL_BIT (1<<12)
+#define TRACE_CONTROL_BIT (1<<13)
+
/*
* Abuse of the trace_recursion.
* As we need a way to maintain state if we are tracing the function
--
1.7.1
--
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