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Commit 75e33751 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Steven Rostedt
Browse files

tracing/ksym_tracer: support quick clear for ksym_trace_filter -- v2 



It's rather boring to clear symbol one by one in ksym_trace_filter
file, so, this patch will let ksym_trace_filter file support quickly
clear all break points. We can write "0" to this file and it will clear
all symbols

for example:
 # cat ksym_trace_filter
 ksym_filter_head:rw-
 global_trace:rw-
 # echo 0 > ksym_trace_filter
 # cat ksym_trace_filter
 #

Changelog v1->v2:
Add other ways to clear all breakpoints by writing NULL or "*:---"
to ksym_trace_filter file base on K.Prasad's suggestion

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
LKML-Reference: <4A67E092.3080202@cn.fujitsu.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 8e068542

kernel/trace/trace_ksym.c

+35 −18
Original line number Diff line number Diff line
@@ -163,8 +163,6 @@ static int parse_ksym_trace_str(char *input_string, char **ksymname, 
{

	int ret;



	strstrip(input_string);



	*ksymname = strsep(&input_string, ":");

	*addr = kallsyms_lookup_name(*ksymname);
@@ -262,6 +260,25 @@ static ssize_t ksym_trace_filter_read(struct file *filp, char __user *ubuf, 
	return cnt;

}



static void __ksym_trace_reset(void)

{

	struct trace_ksym *entry;

	struct hlist_node *node, *node1;



	mutex_lock(&ksym_tracer_mutex);

	hlist_for_each_entry_safe(entry, node, node1, &ksym_filter_head,

								ksym_hlist) {

		unregister_kernel_hw_breakpoint(entry->ksym_hbp);

		ksym_filter_entry_count--;

		hlist_del_rcu(&(entry->ksym_hlist));

		synchronize_rcu();

		kfree(entry->ksym_hbp->info.name);

		kfree(entry->ksym_hbp);

		kfree(entry);

	}

	mutex_unlock(&ksym_tracer_mutex);

}



static ssize_t ksym_trace_filter_write(struct file *file,

					const char __user *buffer,

						size_t count, loff_t *ppos)
@@ -282,6 +299,21 @@ static ssize_t ksym_trace_filter_write(struct file *file, 
	}

	input_string[count] = '\0';



	strstrip(input_string);



	/*

	 * Clear all breakpoints if:

	 * 1: echo > ksym_trace_filter

	 * 2: echo 0 > ksym_trace_filter

	 * 3: echo "*:---" > ksym_trace_filter

	 */

	if (!input_string[0] || !strcmp(input_string, "0") ||

	    !strcmp(input_string, "*:---")) {

		__ksym_trace_reset();

		kfree(input_string);

		return count;

	}



	ret = op = parse_ksym_trace_str(input_string, &ksymname, &ksym_addr);

	if (ret < 0) {

		kfree(input_string);
@@ -341,23 +373,8 @@ static const struct file_operations ksym_tracing_fops = { 


static void ksym_trace_reset(struct trace_array *tr)

{

	struct trace_ksym *entry;

	struct hlist_node *node, *node1;



	ksym_tracing_enabled = 0;



	mutex_lock(&ksym_tracer_mutex);

	hlist_for_each_entry_safe(entry, node, node1, &ksym_filter_head,

								ksym_hlist) {

		unregister_kernel_hw_breakpoint(entry->ksym_hbp);

		ksym_filter_entry_count--;

		hlist_del_rcu(&(entry->ksym_hlist));

		synchronize_rcu();

		kfree(entry->ksym_hbp->info.name);

		kfree(entry->ksym_hbp);

		kfree(entry);

	}

	mutex_unlock(&ksym_tracer_mutex);

	__ksym_trace_reset();

}



static int ksym_trace_init(struct trace_array *tr)