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tracing/ftrace: replace none tracer by nop tracer

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Replace "none" tracer by the recently created "nop" tracer.
Both are pretty similar except that nop accepts TRACE_PRINT
or TRACE_SPECIAL entries.

And as a consequence, changing the size of the ring buffer now
requires that tracing has already been disabled.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Frédéric Weisbecker 2008-09-21 20:16:30 +02:00 committed by Ingo Molnar
parent 2a3a4f669d
commit 43a15386c4
3 changed files with 12 additions and 46 deletions
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49
kernel/trace/trace.c
View file

@ -142,24 +142,6 @@ static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
/* trace_flags holds iter_ctrl options */
unsigned long trace_flags = TRACE_ITER_PRINT_PARENT;
static notrace void no_trace_init(struct trace_array *tr)
{
int cpu;
ftrace_function_enabled = 0;
if(tr->ctrl)
for_each_online_cpu(cpu)
tracing_reset(tr->data[cpu]);
tracer_enabled = 0;
}
/* dummy trace to disable tracing */
static struct tracer no_tracer __read_mostly = {
.name = "none",
.init = no_trace_init
};
/**
* trace_wake_up - wake up tasks waiting for trace input
*
@ -962,7 +944,7 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
long disabled;
int cpu;
if (tracing_disabled || current_trace == &no_tracer || !tr->ctrl)
if (tracing_disabled || !tr->ctrl)
return;
local_irq_save(flags);
@ -2795,6 +2777,7 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
unsigned long val;
char buf[64];
int i, ret;
struct trace_array *tr = filp->private_data;
if (cnt >= sizeof(buf))
return -EINVAL;
@ -2814,9 +2797,9 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
mutex_lock(&trace_types_lock);
if (current_trace != &no_tracer) {
if (tr->ctrl) {
cnt = -EBUSY;
pr_info("ftrace: set current_tracer to none"
pr_info("ftrace: please disable tracing"
" before modifying buffer size\n");
goto out;
}
@ -2879,20 +2862,6 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
return cnt;
}
static int tracing_open_mark(struct inode *inode, struct file *filp)
{
int ret;
ret = tracing_open_generic(inode, filp);
if (ret)
return ret;
if (current_trace == &no_tracer)
return -ENODEV;
return 0;
}
static int mark_printk(const char *fmt, ...)
{
int ret;
@ -2911,7 +2880,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
char *end;
struct trace_array *tr = &global_trace;
if (current_trace == &no_tracer || !tr->ctrl || tracing_disabled)
if (!tr->ctrl || tracing_disabled)
return -EINVAL;
if (cnt > TRACE_BUF_SIZE)
@ -2971,7 +2940,7 @@ static struct file_operations tracing_entries_fops = {
};
static struct file_operations tracing_mark_fops = {
.open = tracing_open_mark,
.open = tracing_open_generic,
.write = tracing_mark_write,
};
@ -3123,7 +3092,7 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
long disabled;
int cpu, len = 0, write, written = 0;
if (current_trace == &no_tracer || !tr->ctrl || tracing_disabled)
if (!tr->ctrl || tracing_disabled)
return 0;
local_irq_save(flags);
@ -3539,8 +3508,8 @@ __init static int tracer_alloc_buffers(void)
trace_init_cmdlines();
register_tracer(&no_tracer);
current_trace = &no_tracer;
register_tracer(&nop_trace);
current_trace = &nop_trace;
/* All seems OK, enable tracing */
global_trace.ctrl = tracer_enabled;

2
kernel/trace/trace.h
View file

@ -369,4 +369,6 @@ enum trace_iterator_flags {
TRACE_ITER_PRINTK = 0x400,
};
extern struct tracer nop_trace;
#endif /* _LINUX_KERNEL_TRACE_H */

7
kernel/trace/trace_nop.c
View file

@ -51,7 +51,7 @@ static void nop_trace_ctrl_update(struct trace_array *tr)
stop_nop_trace(tr);
}
static struct tracer nop_trace __read_mostly =
struct tracer nop_trace __read_mostly =
{
.name = "nop",
.init = nop_trace_init,
@ -62,8 +62,3 @@ static struct tracer nop_trace __read_mostly =
#endif
};
__init static int init_nop_trace(void)
{
return register_tracer(&nop_trace);
}
device_initcall(init_nop_trace);