Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 8aaf1ee7 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

tracing: Rename trace_active to disable_stack_tracer and inline its modification 



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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 5367278c

include/linux/ftrace.h

+34 −2
Original line number Diff line number Diff line
@@ -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) { }

kernel/trace/trace_stack.c

+9 −41
Original line number Diff line number Diff line
@@ -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();

}