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Subject[PATCH 07/10] function-graph: use int instead of atomic for ftrace_graph_active
From: Steven Rostedt <srostedt@redhat.com>

Impact: cleanup

The variable ftrace_graph_active is only modified under the
ftrace_lock mutex, thus an atomic is not necessary for modification.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/ftrace.c | 14 +++++++-------
1 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6ea5a1a..8e6a0b5 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3092,7 +3092,7 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

-static atomic_t ftrace_graph_active;
+static int ftrace_graph_active;
static struct notifier_block ftrace_suspend_notifier;

int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
@@ -3244,7 +3244,7 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
mutex_lock(&ftrace_lock);

/* we currently allow only one tracer registered at a time */
- if (atomic_read(&ftrace_graph_active)) {
+ if (ftrace_graph_active) {
ret = -EBUSY;
goto out;
}
@@ -3252,10 +3252,10 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
ftrace_suspend_notifier.notifier_call = ftrace_suspend_notifier_call;
register_pm_notifier(&ftrace_suspend_notifier);

- atomic_inc(&ftrace_graph_active);
+ ftrace_graph_active++;
ret = start_graph_tracing();
if (ret) {
- atomic_dec(&ftrace_graph_active);
+ ftrace_graph_active--;
goto out;
}

@@ -3273,10 +3273,10 @@ void unregister_ftrace_graph(void)
{
mutex_lock(&ftrace_lock);

- if (!unlikely(atomic_read(&ftrace_graph_active)))
+ if (unlikely(!ftrace_graph_active))
goto out;

- atomic_dec(&ftrace_graph_active);
+ ftrace_graph_active--;
unregister_trace_sched_switch(ftrace_graph_probe_sched_switch);
ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
ftrace_graph_entry = ftrace_graph_entry_stub;
@@ -3290,7 +3290,7 @@ void unregister_ftrace_graph(void)
/* Allocate a return stack for newly created task */
void ftrace_graph_init_task(struct task_struct *t)
{
- if (atomic_read(&ftrace_graph_active)) {
+ if (ftrace_graph_active) {
t->ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
* sizeof(struct ftrace_ret_stack),
GFP_KERNEL);
--
1.6.2.1
--


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