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Commit ee6c2c1b authored by Li Zefan's avatar Li Zefan Committed by Steven Rostedt
Browse files

tracing: remove max_tracer_type_len 



Limit the length of a tracer's name within 100 chars, and then we
don't have to play with max_tracer_type_len.

Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4AB32377.9020601@cn.fujitsu.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent a4ec5e0c

kernel/trace/trace.c

+16 −33
Original line number Diff line number Diff line
@@ -125,13 +125,13 @@ int ftrace_dump_on_oops; 


static int tracing_set_tracer(const char *buf);



#define BOOTUP_TRACER_SIZE		100

static char bootup_tracer_buf[BOOTUP_TRACER_SIZE] __initdata;

#define MAX_TRACER_SIZE		100

static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;

static char *default_bootup_tracer;



static int __init set_ftrace(char *str)

{

	strncpy(bootup_tracer_buf, str, BOOTUP_TRACER_SIZE);

	strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);

	default_bootup_tracer = bootup_tracer_buf;

	/* We are using ftrace early, expand it */

	ring_buffer_expanded = 1;
@@ -241,13 +241,6 @@ static struct tracer *trace_types __read_mostly; 
/* current_trace points to the tracer that is currently active */

static struct tracer		*current_trace __read_mostly;



/*

 * max_tracer_type_len is used to simplify the allocating of

 * buffers to read userspace tracer names. We keep track of

 * the longest tracer name registered.

 */

static int			max_tracer_type_len;



/*

 * trace_types_lock is used to protect the trace_types list.

 * This lock is also used to keep user access serialized.
@@ -619,7 +612,6 @@ __releases(kernel_lock) 
__acquires(kernel_lock)

{

	struct tracer *t;

	int len;

	int ret = 0;



	if (!type->name) {
@@ -627,6 +619,11 @@ __acquires(kernel_lock) 
		return -1;

	}



	if (strlen(type->name) > MAX_TRACER_SIZE) {

		pr_info("Tracer has a name longer than %d\n", MAX_TRACER_SIZE);

		return -1;

	}



	/*

	 * When this gets called we hold the BKL which means that

	 * preemption is disabled. Various trace selftests however
@@ -641,7 +638,7 @@ __acquires(kernel_lock) 
	for (t = trace_types; t; t = t->next) {

		if (strcmp(type->name, t->name) == 0) {

			/* already found */

			pr_info("Trace %s already registered\n",

			pr_info("Tracer %s already registered\n",

				type->name);

			ret = -1;

			goto out;
@@ -692,9 +689,6 @@ __acquires(kernel_lock) 


	type->next = trace_types;

	trace_types = type;

	len = strlen(type->name);

	if (len > max_tracer_type_len)

		max_tracer_type_len = len;



 out:

	tracing_selftest_running = false;
@@ -703,7 +697,7 @@ __acquires(kernel_lock) 
	if (ret || !default_bootup_tracer)

		goto out_unlock;



	if (strncmp(default_bootup_tracer, type->name, BOOTUP_TRACER_SIZE))

	if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))

		goto out_unlock;



	printk(KERN_INFO "Starting tracer '%s'\n", type->name);
@@ -725,14 +719,13 @@ __acquires(kernel_lock) 
void unregister_tracer(struct tracer *type)

{

	struct tracer **t;

	int len;



	mutex_lock(&trace_types_lock);

	for (t = &trace_types; *t; t = &(*t)->next) {

		if (*t == type)

			goto found;

	}

	pr_info("Trace %s not registered\n", type->name);

	pr_info("Tracer %s not registered\n", type->name);

	goto out;



 found:
@@ -745,16 +738,6 @@ void unregister_tracer(struct tracer *type) 
			current_trace->stop(&global_trace);

		current_trace = &nop_trace;

	}



	if (strlen(type->name) != max_tracer_type_len)

		goto out;



	max_tracer_type_len = 0;

	for (t = &trace_types; *t; t = &(*t)->next) {

		len = strlen((*t)->name);

		if (len > max_tracer_type_len)

			max_tracer_type_len = len;

	}

out:

	mutex_unlock(&trace_types_lock);

}
@@ -2604,7 +2587,7 @@ static ssize_t 
tracing_set_trace_read(struct file *filp, char __user *ubuf,

		       size_t cnt, loff_t *ppos)

{

	char buf[max_tracer_type_len+2];

	char buf[MAX_TRACER_SIZE+2];

	int r;



	mutex_lock(&trace_types_lock);
@@ -2754,15 +2737,15 @@ static ssize_t 
tracing_set_trace_write(struct file *filp, const char __user *ubuf,

			size_t cnt, loff_t *ppos)

{

	char buf[max_tracer_type_len+1];

	char buf[MAX_TRACER_SIZE+1];

	int i;

	size_t ret;

	int err;



	ret = cnt;



	if (cnt > max_tracer_type_len)

		cnt = max_tracer_type_len;

	if (cnt > MAX_TRACER_SIZE)

		cnt = MAX_TRACER_SIZE;



	if (copy_from_user(&buf, ubuf, cnt))

		return -EFAULT;