linux/kernel/trace/trace_functions.c
Xiao Guangrong 04aef32d39 tracing/function: Fix the return value of ftrace_trace_onoff_callback()
ftrace_trace_onoff_callback() will return an error even if we do the
right operation, for example:

 # echo _spin_*:traceon:10 > set_ftrace_filter
 -bash: echo: write error: Invalid argument
 # cat set_ftrace_filter
 #### all functions enabled ####
 _spin_trylock_bh:traceon:count=10
 _spin_unlock_irq:traceon:count=10
 _spin_unlock_bh:traceon:count=10
 _spin_lock_irq:traceon:count=10
 _spin_unlock:traceon:count=10
 _spin_trylock:traceon:count=10
 _spin_unlock_irqrestore:traceon:count=10
 _spin_lock_irqsave:traceon:count=10
 _spin_lock_bh:traceon:count=10
 _spin_lock:traceon:count=10

We want to set _spin_*:traceon:10 to set_ftrace_filter, it complains
with "Invalid argument", but the operation is successful.

This is because ftrace_process_regex() returns the number of functions that
matched the pattern. If the number is not 0, this value is returned
by ftrace_regex_write() whereas we want to return the number of bytes
virtually written.
Also the file offset pointer is not updated in this case.

If the number of matched functions is lower than the number of bytes written
by the user, this results to a reprocessing of the string given by the user with
a lower size, leading to a malformed ftrace regex and then a -EINVAL returned.

So, this patch fixes it by returning 0 if no error occured.
The fix also applies on 2.6.30

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: stable@kernel.org
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2009-07-16 23:34:32 -04:00

405 lines
8.2 KiB
C

/*
* ring buffer based function tracer
*
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
*
* Based on code from the latency_tracer, that is:
*
* Copyright (C) 2004-2006 Ingo Molnar
* Copyright (C) 2004 William Lee Irwin III
*/
#include <linux/ring_buffer.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/fs.h>
#include "trace.h"
/* function tracing enabled */
static int ftrace_function_enabled;
static struct trace_array *func_trace;
static void tracing_start_function_trace(void);
static void tracing_stop_function_trace(void);
static int function_trace_init(struct trace_array *tr)
{
func_trace = tr;
tr->cpu = get_cpu();
put_cpu();
tracing_start_cmdline_record();
tracing_start_function_trace();
return 0;
}
static void function_trace_reset(struct trace_array *tr)
{
tracing_stop_function_trace();
tracing_stop_cmdline_record();
}
static void function_trace_start(struct trace_array *tr)
{
tracing_reset_online_cpus(tr);
}
static void
function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
{
struct trace_array *tr = func_trace;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu, resched;
int pc;
if (unlikely(!ftrace_function_enabled))
return;
pc = preempt_count();
resched = ftrace_preempt_disable();
local_save_flags(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
trace_function(tr, ip, parent_ip, flags, pc);
atomic_dec(&data->disabled);
ftrace_preempt_enable(resched);
}
static void
function_trace_call(unsigned long ip, unsigned long parent_ip)
{
struct trace_array *tr = func_trace;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
int pc;
if (unlikely(!ftrace_function_enabled))
return;
/*
* Need to use raw, since this must be called before the
* recursive protection is performed.
*/
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1)) {
pc = preempt_count();
trace_function(tr, ip, parent_ip, flags, pc);
}
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
static void
function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
{
struct trace_array *tr = func_trace;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
int pc;
if (unlikely(!ftrace_function_enabled))
return;
/*
* Need to use raw, since this must be called before the
* recursive protection is performed.
*/
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1)) {
pc = preempt_count();
trace_function(tr, ip, parent_ip, flags, pc);
/*
* skip over 5 funcs:
* __ftrace_trace_stack,
* __trace_stack,
* function_stack_trace_call
* ftrace_list_func
* ftrace_call
*/
__trace_stack(tr, flags, 5, pc);
}
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
static struct ftrace_ops trace_ops __read_mostly =
{
.func = function_trace_call,
};
static struct ftrace_ops trace_stack_ops __read_mostly =
{
.func = function_stack_trace_call,
};
/* Our two options */
enum {
TRACE_FUNC_OPT_STACK = 0x1,
};
static struct tracer_opt func_opts[] = {
#ifdef CONFIG_STACKTRACE
{ TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
#endif
{ } /* Always set a last empty entry */
};
static struct tracer_flags func_flags = {
.val = 0, /* By default: all flags disabled */
.opts = func_opts
};
static void tracing_start_function_trace(void)
{
ftrace_function_enabled = 0;
if (trace_flags & TRACE_ITER_PREEMPTONLY)
trace_ops.func = function_trace_call_preempt_only;
else
trace_ops.func = function_trace_call;
if (func_flags.val & TRACE_FUNC_OPT_STACK)
register_ftrace_function(&trace_stack_ops);
else
register_ftrace_function(&trace_ops);
ftrace_function_enabled = 1;
}
static void tracing_stop_function_trace(void)
{
ftrace_function_enabled = 0;
if (func_flags.val & TRACE_FUNC_OPT_STACK)
unregister_ftrace_function(&trace_stack_ops);
else
unregister_ftrace_function(&trace_ops);
}
static int func_set_flag(u32 old_flags, u32 bit, int set)
{
if (bit == TRACE_FUNC_OPT_STACK) {
/* do nothing if already set */
if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
return 0;
if (set) {
unregister_ftrace_function(&trace_ops);
register_ftrace_function(&trace_stack_ops);
} else {
unregister_ftrace_function(&trace_stack_ops);
register_ftrace_function(&trace_ops);
}
return 0;
}
return -EINVAL;
}
static struct tracer function_trace __read_mostly =
{
.name = "function",
.init = function_trace_init,
.reset = function_trace_reset,
.start = function_trace_start,
.wait_pipe = poll_wait_pipe,
.flags = &func_flags,
.set_flag = func_set_flag,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_function,
#endif
};
#ifdef CONFIG_DYNAMIC_FTRACE
static void
ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
{
long *count = (long *)data;
if (tracing_is_on())
return;
if (!*count)
return;
if (*count != -1)
(*count)--;
tracing_on();
}
static void
ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
{
long *count = (long *)data;
if (!tracing_is_on())
return;
if (!*count)
return;
if (*count != -1)
(*count)--;
tracing_off();
}
static int
ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
struct ftrace_probe_ops *ops, void *data);
static struct ftrace_probe_ops traceon_probe_ops = {
.func = ftrace_traceon,
.print = ftrace_trace_onoff_print,
};
static struct ftrace_probe_ops traceoff_probe_ops = {
.func = ftrace_traceoff,
.print = ftrace_trace_onoff_print,
};
static int
ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
struct ftrace_probe_ops *ops, void *data)
{
char str[KSYM_SYMBOL_LEN];
long count = (long)data;
kallsyms_lookup(ip, NULL, NULL, NULL, str);
seq_printf(m, "%s:", str);
if (ops == &traceon_probe_ops)
seq_printf(m, "traceon");
else
seq_printf(m, "traceoff");
if (count == -1)
seq_printf(m, ":unlimited\n");
else
seq_printf(m, ":count=%ld\n", count);
return 0;
}
static int
ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
{
struct ftrace_probe_ops *ops;
/* we register both traceon and traceoff to this callback */
if (strcmp(cmd, "traceon") == 0)
ops = &traceon_probe_ops;
else
ops = &traceoff_probe_ops;
unregister_ftrace_function_probe_func(glob, ops);
return 0;
}
static int
ftrace_trace_onoff_callback(char *glob, char *cmd, char *param, int enable)
{
struct ftrace_probe_ops *ops;
void *count = (void *)-1;
char *number;
int ret;
/* hash funcs only work with set_ftrace_filter */
if (!enable)
return -EINVAL;
if (glob[0] == '!')
return ftrace_trace_onoff_unreg(glob+1, cmd, param);
/* we register both traceon and traceoff to this callback */
if (strcmp(cmd, "traceon") == 0)
ops = &traceon_probe_ops;
else
ops = &traceoff_probe_ops;
if (!param)
goto out_reg;
number = strsep(&param, ":");
if (!strlen(number))
goto out_reg;
/*
* We use the callback data field (which is a pointer)
* as our counter.
*/
ret = strict_strtoul(number, 0, (unsigned long *)&count);
if (ret)
return ret;
out_reg:
ret = register_ftrace_function_probe(glob, ops, count);
return ret < 0 ? ret : 0;
}
static struct ftrace_func_command ftrace_traceon_cmd = {
.name = "traceon",
.func = ftrace_trace_onoff_callback,
};
static struct ftrace_func_command ftrace_traceoff_cmd = {
.name = "traceoff",
.func = ftrace_trace_onoff_callback,
};
static int __init init_func_cmd_traceon(void)
{
int ret;
ret = register_ftrace_command(&ftrace_traceoff_cmd);
if (ret)
return ret;
ret = register_ftrace_command(&ftrace_traceon_cmd);
if (ret)
unregister_ftrace_command(&ftrace_traceoff_cmd);
return ret;
}
#else
static inline int init_func_cmd_traceon(void)
{
return 0;
}
#endif /* CONFIG_DYNAMIC_FTRACE */
static __init int init_function_trace(void)
{
init_func_cmd_traceon();
return register_tracer(&function_trace);
}
device_initcall(init_function_trace);