Commit 0b9b12c1 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Steven Rostedt
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tracing: Move ftrace_max_lock into trace_array 



In preparation for having tracers enabled in instances, the max_lock
should be unique as updating the max for one tracer is a separate
operation than updating it for another tracer using a different max.

Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 6d9b3fa5

kernel/trace/trace.c

+14 −26
Original line number Diff line number Diff line
@@ -963,22 +963,6 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt) 
	return cnt;

}



/*

 * ftrace_max_lock is used to protect the swapping of buffers

 * when taking a max snapshot. The buffers themselves are

 * protected by per_cpu spinlocks. But the action of the swap

 * needs its own lock.

 *

 * This is defined as a arch_spinlock_t in order to help

 * with performance when lockdep debugging is enabled.

 *

 * It is also used in other places outside the update_max_tr

 * so it needs to be defined outside of the

 * CONFIG_TRACER_MAX_TRACE.

 */

static arch_spinlock_t ftrace_max_lock =

	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;



unsigned long __read_mostly	tracing_thresh;



#ifdef CONFIG_TRACER_MAX_TRACE
@@ -1046,14 +1030,14 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) 
		return;

	}



	arch_spin_lock(&ftrace_max_lock);

	arch_spin_lock(&tr->max_lock);



	buf = tr->trace_buffer.buffer;

	tr->trace_buffer.buffer = tr->max_buffer.buffer;

	tr->max_buffer.buffer = buf;



	__update_max_tr(tr, tsk, cpu);

	arch_spin_unlock(&ftrace_max_lock);

	arch_spin_unlock(&tr->max_lock);

}



/**
@@ -1079,7 +1063,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu) 
		return;

	}



	arch_spin_lock(&ftrace_max_lock);

	arch_spin_lock(&tr->max_lock);



	ret = ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->trace_buffer.buffer, cpu);
@@ -1097,7 +1081,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu) 
	WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY);



	__update_max_tr(tr, tsk, cpu);

	arch_spin_unlock(&ftrace_max_lock);

	arch_spin_unlock(&tr->max_lock);

}

#endif /* CONFIG_TRACER_MAX_TRACE */
@@ -1351,7 +1335,7 @@ void tracing_start(void) 
	}



	/* Prevent the buffers from switching */

	arch_spin_lock(&ftrace_max_lock);

	arch_spin_lock(&global_trace.max_lock);



	buffer = global_trace.trace_buffer.buffer;

	if (buffer)
@@ -1363,7 +1347,7 @@ void tracing_start(void) 
		ring_buffer_record_enable(buffer);

#endif



	arch_spin_unlock(&ftrace_max_lock);

	arch_spin_unlock(&global_trace.max_lock);



	ftrace_start();

 out:
@@ -1418,7 +1402,7 @@ void tracing_stop(void) 
		goto out;



	/* Prevent the buffers from switching */

	arch_spin_lock(&ftrace_max_lock);

	arch_spin_lock(&global_trace.max_lock);



	buffer = global_trace.trace_buffer.buffer;

	if (buffer)
@@ -1430,7 +1414,7 @@ void tracing_stop(void) 
		ring_buffer_record_disable(buffer);

#endif



	arch_spin_unlock(&ftrace_max_lock);

	arch_spin_unlock(&global_trace.max_lock);



 out:

	raw_spin_unlock_irqrestore(&global_trace.start_lock, flags);
@@ -3331,7 +3315,7 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf, 
	mutex_lock(&tracing_cpumask_update_lock);



	local_irq_disable();

	arch_spin_lock(&ftrace_max_lock);

	arch_spin_lock(&tr->max_lock);

	for_each_tracing_cpu(cpu) {

		/*

		 * Increase/decrease the disabled counter if we are
@@ -3348,7 +3332,7 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf, 
			ring_buffer_record_enable_cpu(tr->trace_buffer.buffer, cpu);

		}

	}

	arch_spin_unlock(&ftrace_max_lock);

	arch_spin_unlock(&tr->max_lock);

	local_irq_enable();



	cpumask_copy(tr->tracing_cpumask, tracing_cpumask_new);
@@ -6129,6 +6113,8 @@ static int new_instance_create(const char *name) 


	raw_spin_lock_init(&tr->start_lock);



	tr->max_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;



	tr->current_trace = &nop_trace;



	INIT_LIST_HEAD(&tr->systems);
@@ -6627,6 +6613,8 @@ __init static int tracer_alloc_buffers(void) 
	 */

	global_trace.current_trace = &nop_trace;



	global_trace.max_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;



	ftrace_init_global_array_ops(&global_trace);



	register_tracer(&nop_trace);

kernel/trace/trace.h

+14 −0
Original line number Diff line number Diff line
@@ -192,6 +192,20 @@ struct trace_array { 
	bool			allocated_snapshot;

	unsigned long		max_latency;

#endif

	/*

	 * max_lock is used to protect the swapping of buffers

	 * when taking a max snapshot. The buffers themselves are

	 * protected by per_cpu spinlocks. But the action of the swap

	 * needs its own lock.

	 *

	 * This is defined as a arch_spinlock_t in order to help

	 * with performance when lockdep debugging is enabled.

	 *

	 * It is also used in other places outside the update_max_tr

	 * so it needs to be defined outside of the

	 * CONFIG_TRACER_MAX_TRACE.

	 */

	arch_spinlock_t		max_lock;

	int			buffer_disabled;

#ifdef CONFIG_FTRACE_SYSCALLS

	int			sys_refcount_enter;

kernel/trace/trace_selftest.c

+2 −2
Original line number Diff line number Diff line
@@ -65,7 +65,7 @@ static int trace_test_buffer(struct trace_buffer *buf, unsigned long *count) 


	/* Don't allow flipping of max traces now */

	local_irq_save(flags);

	arch_spin_lock(&ftrace_max_lock);

	arch_spin_lock(&buf->tr->max_lock);



	cnt = ring_buffer_entries(buf->buffer);
@@ -83,7 +83,7 @@ static int trace_test_buffer(struct trace_buffer *buf, unsigned long *count) 
			break;

	}

	tracing_on();

	arch_spin_unlock(&ftrace_max_lock);

	arch_spin_unlock(&buf->tr->max_lock);

	local_irq_restore(flags);



	if (count)

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