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Message-ID: <48D68F7E.5020609@gmail.com>
Date: Sun, 21 Sep 2008 20:16:30 +0200
From: Frédéric Weisbecker <fweisbec@...il.com>
To: Ingo Molnar <mingo@...e.hu>
CC: Linux Kernel <linux-kernel@...r.kernel.org>,
Steven Rostedt <rostedt@...dmis.org>,
Steven Noonan <steven@...inklabs.net>
Subject: [Patch 3/3] Tracing/ftrace: Replace none tracer by nop tracer
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@...il.com>
---
diff -rup linux-2.6-tip (2)/kernel/trace/trace.c linux-2.6-tip/kernel/trace/trace.c
--- linux-2.6-tip (2)/kernel/trace/trace.c 2008-09-18 18:40:00.000000000 +0200
+++ linux-2.6-tip/kernel/trace/trace.c 2008-09-20 17:13:08.000000000 +0200
@@ -142,24 +142,6 @@ static DECLARE_WAIT_QUEUE_HEAD(trace_wai
/* 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, unsig
long disabled;
int cpu;
- if (tracing_disabled || current_trace == &no_tracer || !tr->ctrl)
+ if (tracing_disabled || !tr->ctrl)
return;
local_irq_save(flags);
@@ -2794,7 +2776,8 @@ tracing_entries_write(struct file *filp,
{
unsigned long val;
char buf[64];
- int i, ret;
+ 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,
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,
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, co
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_en
};
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, cons
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(v
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;
diff -rup linux-2.6-tip (2)/kernel/trace/trace.h linux-2.6-tip/kernel/trace/trace.h
--- linux-2.6-tip (2)/kernel/trace/trace.h 2008-09-19 18:01:26.000000000 +0200
+++ linux-2.6-tip/kernel/trace/trace.h 2008-09-20 17:23:36.000000000 +0200
@@ -384,5 +384,7 @@ enum trace_iterator_flags {
TRACE_ITER_SCHED_TREE = 0x200,
TRACE_ITER_PRINTK = 0x400,
};
+
+extern struct tracer nop_trace;
#endif /* _LINUX_KERNEL_TRACE_H */
diff -rup linux-2.6-tip (2)/kernel/trace/trace_nop.c linux-2.6-tip/kernel/trace/trace_nop.c
--- linux-2.6-tip (2)/kernel/trace/trace_nop.c 2008-09-19 18:01:26.000000000 +0200
+++ linux-2.6-tip/kernel/trace/trace_nop.c 2008-09-21 00:44:47.000000000 +0200
@@ -47,7 +51,7 @@ static void nop_trace_ctrl_update(struct
stop_nop_trace(tr);
}
-static struct tracer nop_trace __read_mostly =
+struct tracer nop_trace __read_mostly =
{
.name = "nop",
.init = nop_trace_init,
@@ -57,9 +61,4 @@ static struct tracer nop_trace __read_mo
.selftest = trace_selftest_startup_nop,
#endif
};
-
-__init static int init_nop_trace(void)
-{
- return register_tracer(&nop_trace);
-}
-device_initcall(init_nop_trace);
+
--
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