Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[linux-2.6-omap-h63xx.git] / kernel / trace / trace_stack.c

diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 0b863f2cbc8e3ff04c9ea8347f4ffb6795dab446..d0871bc0aca5d0f670f9363cf49489fd9e85cf0c 100644 (file)
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -10,6 +10,7 @@
 #include <linux/debugfs.h>
 #include <linux/ftrace.h>
 #include <linux/module.h>
+#include <linux/sysctl.h>
 #include <linux/init.h>
 #include <linux/fs.h>
 #include "trace.h"
@@ -31,6 +32,10 @@ static raw_spinlock_t max_stack_lock =
 
 static int stack_trace_disabled __read_mostly;
 static DEFINE_PER_CPU(int, trace_active);
+static DEFINE_MUTEX(stack_sysctl_mutex);
+
+int stack_tracer_enabled;
+static int last_stack_tracer_enabled;
 
 static inline void check_stack(void)
 {
@@ -174,7 +179,7 @@ stack_max_size_write(struct file *filp, const char __user *ubuf,
        return count;
 }
 
-static struct file_operations stack_max_size_fops = {
+static const struct file_operations stack_max_size_fops = {
        .open           = tracing_open_generic,
        .read           = stack_max_size_read,
        .write          = stack_max_size_write,
@@ -272,7 +277,7 @@ static int t_show(struct seq_file *m, void *v)
        return 0;
 }
 
-static struct seq_operations stack_trace_seq_ops = {
+static const struct seq_operations stack_trace_seq_ops = {
        .start          = t_start,
        .next           = t_next,
        .stop           = t_stop,
@@ -288,12 +293,47 @@ static int stack_trace_open(struct inode *inode, struct file *file)
        return ret;
 }
 
-static struct file_operations stack_trace_fops = {
+static const struct file_operations stack_trace_fops = {
        .open           = stack_trace_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
 };
 
+int
+stack_trace_sysctl(struct ctl_table *table, int write,
+                  struct file *file, void __user *buffer, size_t *lenp,
+                  loff_t *ppos)
+{
+       int ret;
+
+       mutex_lock(&stack_sysctl_mutex);
+
+       ret = proc_dointvec(table, write, file, buffer, lenp, ppos);
+
+       if (ret || !write ||
+           (last_stack_tracer_enabled == stack_tracer_enabled))
+               goto out;
+
+       last_stack_tracer_enabled = stack_tracer_enabled;
+
+       if (stack_tracer_enabled)
+               register_ftrace_function(&trace_ops);
+       else
+               unregister_ftrace_function(&trace_ops);
+
+ out:
+       mutex_unlock(&stack_sysctl_mutex);
+       return ret;
+}
+
+static __init int enable_stacktrace(char *str)
+{
+       stack_tracer_enabled = 1;
+       last_stack_tracer_enabled = 1;
+       return 1;
+}
+__setup("stacktrace", enable_stacktrace);
+
 static __init int stack_trace_init(void)
 {
        struct dentry *d_tracer;
@@ -311,7 +351,8 @@ static __init int stack_trace_init(void)
        if (!entry)
                pr_warning("Could not create debugfs 'stack_trace' entry\n");
 
-       register_ftrace_function(&trace_ops);
+       if (stack_tracer_enabled)
+               register_ftrace_function(&trace_ops);
 
        return 0;
 }