---

yaml
---
r: 116603
b: refs/heads/master
c: e5a81b6
h: refs/heads/master
i:
  116601: b6cb9b4
  116599: cbb398e
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b3a320417484a6d6b9d28098944df58341353992
+refs/heads/master: e5a81b629ea8feb9e7530cfac35cfb41c45facf3

trunk/kernel/trace/Kconfig

@@ -106,6 +106,15 @@ config CONTEXT_SWITCH_TRACER
 	  This tracer gets called from the context switch and records
 	  all switching of tasks.
 
+config STACK_TRACER
+	bool "Trace max stack"
+	depends on HAVE_FTRACE
+	select FTRACE
+	select STACKTRACE
+	help
+	  This tracer records the max stack of the kernel, and displays
+	  it in debugfs/tracing/stack_trace
+
 config DYNAMIC_FTRACE
 	bool "enable/disable ftrace tracepoints dynamically"
 	depends on FTRACE

trunk/kernel/trace/Makefile

@@ -19,6 +19,7 @@ obj-$(CONFIG_FTRACE) += trace_functions.o
 obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
 obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
 obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
+obj-$(CONFIG_STACK_TRACER) += trace_stack.o
 obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o
 
 libftrace-y := ftrace.o

trunk/kernel/trace/trace_stack.c

@@ -0,0 +1,254 @@
+/*
+ * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
+ *
+ */
+#include <linux/stacktrace.h>
+#include <linux/kallsyms.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/debugfs.h>
+#include <linux/ftrace.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include "trace.h"
+
+#define STACK_TRACE_ENTRIES 500
+
+static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES] =
+	{ [0 ... (STACK_TRACE_ENTRIES-1)] = ULONG_MAX };
+static struct stack_trace max_stack_trace = {
+	.max_entries		= STACK_TRACE_ENTRIES,
+	.entries		= stack_dump_trace,
+};
+
+static unsigned long max_stack_size;
+static raw_spinlock_t max_stack_lock =
+	(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+
+static int stack_trace_disabled __read_mostly;
+static DEFINE_PER_CPU(int, trace_active);
+
+static inline void check_stack(void)
+{
+	unsigned long this_size;
+	unsigned long flags;
+
+	this_size = ((unsigned long)&this_size) & (THREAD_SIZE-1);
+	this_size = THREAD_SIZE - this_size;
+
+	if (this_size <= max_stack_size)
+		return;
+
+	raw_local_irq_save(flags);
+	__raw_spin_lock(&max_stack_lock);
+
+	/* a race could have already updated it */
+	if (this_size <= max_stack_size)
+		goto out;
+
+	max_stack_size = this_size;
+
+	max_stack_trace.nr_entries	= 0;
+	max_stack_trace.skip		= 1;
+
+	save_stack_trace(&max_stack_trace);
+
+ out:
+	__raw_spin_unlock(&max_stack_lock);
+	raw_local_irq_restore(flags);
+}
+
+static void
+stack_trace_call(unsigned long ip, unsigned long parent_ip)
+{
+	int cpu, resched;
+
+	if (unlikely(!ftrace_enabled || stack_trace_disabled))
+		return;
+
+	resched = need_resched();
+	preempt_disable_notrace();
+
+	cpu = raw_smp_processor_id();
+	/* no atomic needed, we only modify this variable by this cpu */
+	if (per_cpu(trace_active, cpu)++ != 0)
+		goto out;
+
+	check_stack();
+
+ out:
+	per_cpu(trace_active, cpu)--;
+	/* prevent recursion in schedule */
+	if (resched)
+		preempt_enable_no_resched_notrace();
+	else
+		preempt_enable_notrace();
+}
+
+static struct ftrace_ops trace_ops __read_mostly =
+{
+	.func = stack_trace_call,
+};
+
+static ssize_t
+stack_max_size_read(struct file *filp, char __user *ubuf,
+		    size_t count, loff_t *ppos)
+{
+	unsigned long *ptr = filp->private_data;
+	char buf[64];
+	int r;
+
+	r = snprintf(buf, sizeof(buf), "%ld\n", *ptr);
+	if (r > sizeof(buf))
+		r = sizeof(buf);
+	return simple_read_from_buffer(ubuf, count, ppos, buf, r);
+}
+
+static ssize_t
+stack_max_size_write(struct file *filp, const char __user *ubuf,
+		     size_t count, loff_t *ppos)
+{
+	long *ptr = filp->private_data;
+	unsigned long val, flags;
+	char buf[64];
+	int ret;
+
+	if (count >= sizeof(buf))
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, count))
+		return -EFAULT;
+
+	buf[count] = 0;
+
+	ret = strict_strtoul(buf, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	raw_local_irq_save(flags);
+	__raw_spin_lock(&max_stack_lock);
+	*ptr = val;
+	__raw_spin_unlock(&max_stack_lock);
+	raw_local_irq_restore(flags);
+
+	return count;
+}
+
+static struct file_operations stack_max_size_fops = {
+	.open		= tracing_open_generic,
+	.read		= stack_max_size_read,
+	.write		= stack_max_size_write,
+};
+
+static void *
+t_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	unsigned long *t = m->private;
+
+	(*pos)++;
+
+	if (!t || *t == ULONG_MAX)
+		return NULL;
+
+	t++;
+	m->private = t;
+
+	return t;
+}
+
+static void *t_start(struct seq_file *m, loff_t *pos)
+{
+	unsigned long *t = m->private;
+	loff_t l = 0;
+
+	local_irq_disable();
+	__raw_spin_lock(&max_stack_lock);
+
+	for (; t && l < *pos; t = t_next(m, t, &l))
+		;
+
+	return t;
+}
+
+static void t_stop(struct seq_file *m, void *p)
+{
+	__raw_spin_unlock(&max_stack_lock);
+	local_irq_enable();
+}
+
+static int trace_lookup_stack(struct seq_file *m, unsigned long addr)
+{
+#ifdef CONFIG_KALLSYMS
+	char str[KSYM_SYMBOL_LEN];
+
+	sprint_symbol(str, addr);
+
+	return seq_printf(m, "[<%p>] %s\n", (void*)addr, str);
+#else
+	return seq_printf(m, "%p\n", (void*)addr);
+#endif
+}
+
+static int t_show(struct seq_file *m, void *v)
+{
+	unsigned long *t = v;
+
+	if (!t || *t == ULONG_MAX)
+		return 0;
+
+	trace_lookup_stack(m, *t);
+
+	return 0;
+}
+
+static struct seq_operations stack_trace_seq_ops = {
+	.start		= t_start,
+	.next		= t_next,
+	.stop		= t_stop,
+	.show		= t_show,
+};
+
+static int stack_trace_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	ret = seq_open(file, &stack_trace_seq_ops);
+	if (!ret) {
+		struct seq_file *m = file->private_data;
+		m->private = stack_dump_trace;
+	}
+
+	return ret;
+}
+
+static struct file_operations stack_trace_fops = {
+	.open		= stack_trace_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+};
+
+static __init int stack_trace_init(void)
+{
+	struct dentry *d_tracer;
+	struct dentry *entry;
+
+	d_tracer = tracing_init_dentry();
+
+	entry = debugfs_create_file("stack_max_size", 0644, d_tracer,
+				    &max_stack_size, &stack_max_size_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'stack_max_size' entry\n");
+
+	entry = debugfs_create_file("stack_trace", 0444, d_tracer,
+				    NULL, &stack_trace_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'stack_trace' entry\n");
+
+	register_ftrace_function(&trace_ops);
+
+	return 0;
+}
+
+device_initcall(stack_trace_init);