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tracing: Rename trace_active to disable_stack_tracer and inline its modification

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In order to eliminate a function call, make "trace_active" into
"disable_stack_tracer" and convert stack_tracer_disable() and friends into
static inline functions.

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2017-04-06 15:47:32 -04:00
parent 5367278cb7
commit 8aaf1ee70e
2 changed files with 43 additions and 43 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

36
include/linux/ftrace.h
View file

@ -287,8 +287,40 @@ stack_trace_sysctl(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos);
void stack_tracer_disable(void);
void stack_tracer_enable(void);
/* DO NOT MODIFY THIS VARIABLE DIRECTLY! */
DECLARE_PER_CPU(int, disable_stack_tracer);
/**
* stack_tracer_disable - temporarily disable the stack tracer
*
* There's a few locations (namely in RCU) where stack tracing
* cannot be executed. This function is used to disable stack
* tracing during those critical sections.
*
* This function must be called with preemption or interrupts
* disabled and stack_tracer_enable() must be called shortly after
* while preemption or interrupts are still disabled.
*/
static inline void stack_tracer_disable(void)
{
/* Preemption or interupts must be disabled */
if (IS_ENABLED(CONFIG_PREEMPT_DEBUG))
WARN_ON_ONCE(!preempt_count() || !irqs_disabled());
this_cpu_inc(disable_stack_tracer);
}
/**
* stack_tracer_enable - re-enable the stack tracer
*
* After stack_tracer_disable() is called, stack_tracer_enable()
* must be called shortly afterward.
*/
static inline void stack_tracer_enable(void)
{
if (IS_ENABLED(CONFIG_PREEMPT_DEBUG))
WARN_ON_ONCE(!preempt_count() || !irqs_disabled());
this_cpu_dec(disable_stack_tracer);
}
#else
static inline void stack_tracer_disable(void) { }
static inline void stack_tracer_enable(void) { }

50
kernel/trace/trace_stack.c
View file

@ -35,44 +35,12 @@ unsigned long stack_trace_max_size;
arch_spinlock_t stack_trace_max_lock =
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
static DEFINE_PER_CPU(int, trace_active);
DEFINE_PER_CPU(int, disable_stack_tracer);
static DEFINE_MUTEX(stack_sysctl_mutex);
int stack_tracer_enabled;
static int last_stack_tracer_enabled;
/**
* stack_tracer_disable - temporarily disable the stack tracer
*
* There's a few locations (namely in RCU) where stack tracing
* cannot be executed. This function is used to disable stack
* tracing during those critical sections.
*
* This function must be called with preemption or interrupts
* disabled and stack_tracer_enable() must be called shortly after
* while preemption or interrupts are still disabled.
*/
void stack_tracer_disable(void)
{
/* Preemption or interupts must be disabled */
if (IS_ENABLED(CONFIG_PREEMPT_DEBUG))
WARN_ON_ONCE(!preempt_count() || !irqs_disabled());
this_cpu_inc(trace_active);
}
/**
* stack_tracer_enable - re-enable the stack tracer
*
* After stack_tracer_disable() is called, stack_tracer_enable()
* must be called shortly afterward.
*/
void stack_tracer_enable(void)
{
if (IS_ENABLED(CONFIG_PREEMPT_DEBUG))
WARN_ON_ONCE(!preempt_count() || !irqs_disabled());
this_cpu_dec(trace_active);
}
void stack_trace_print(void)
{
long i;
@ -243,8 +211,8 @@ stack_trace_call(unsigned long ip, unsigned long parent_ip,
preempt_disable_notrace();
/* no atomic needed, we only modify this variable by this cpu */
__this_cpu_inc(trace_active);
if (__this_cpu_read(trace_active) != 1)
__this_cpu_inc(disable_stack_tracer);
if (__this_cpu_read(disable_stack_tracer) != 1)
goto out;
ip += MCOUNT_INSN_SIZE;
@ -252,7 +220,7 @@ stack_trace_call(unsigned long ip, unsigned long parent_ip,
check_stack(ip, &stack);
out:
__this_cpu_dec(trace_active);
__this_cpu_dec(disable_stack_tracer);
/* prevent recursion in schedule */
preempt_enable_notrace();
}
@ -294,15 +262,15 @@ stack_max_size_write(struct file *filp, const char __user *ubuf,
/*
* In case we trace inside arch_spin_lock() or after (NMI),
* we will cause circular lock, so we also need to increase
* the percpu trace_active here.
* the percpu disable_stack_tracer here.
*/
__this_cpu_inc(trace_active);
__this_cpu_inc(disable_stack_tracer);
arch_spin_lock(&stack_trace_max_lock);
*ptr = val;
arch_spin_unlock(&stack_trace_max_lock);
__this_cpu_dec(trace_active);
__this_cpu_dec(disable_stack_tracer);
local_irq_restore(flags);
return count;
@ -338,7 +306,7 @@ static void *t_start(struct seq_file *m, loff_t *pos)
{
local_irq_disable();
__this_cpu_inc(trace_active);
__this_cpu_inc(disable_stack_tracer);
arch_spin_lock(&stack_trace_max_lock);
@ -352,7 +320,7 @@ static void t_stop(struct seq_file *m, void *p)
{
arch_spin_unlock(&stack_trace_max_lock);
__this_cpu_dec(trace_active);
__this_cpu_dec(disable_stack_tracer);
local_irq_enable();
}