From: "Steven Rostedt (VMware)" <[email protected]> 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.
Signed-off-by: Steven Rostedt (VMware) <[email protected]> --- include/linux/ftrace.h | 36 +++++++++++++++++++++++++++++++-- kernel/trace/trace_stack.c | 50 +++++++++------------------------------------- 2 files changed, 43 insertions(+), 43 deletions(-) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 40afee35565a..4bde7ff2621d 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -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_enabe(void) { } diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 7d52504680f9..84fafb6a331c 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -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(); } -- 2.10.2
