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Commit be9742e6 authored by Li Zefan's avatar Li Zefan Committed by Ingo Molnar
Browse files

ksym_tracer: Rewrite ksym_trace_filter_read() 



Reading ksym_trace_filter gave me some arbitrary characters,
when it should show nothing. It's because buf is not initialized
when there's no filter.

Also reduce stack usage by about 512 bytes.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A52E2B4.6030706@cn.fujitsu.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent db59504d

kernel/trace/trace_ksym.c

+18 −11
Original line number Diff line number Diff line
@@ -35,7 +35,6 @@ 
#define KSYM_TRACER_MAX HBP_NUM



#define KSYM_TRACER_OP_LEN 3 /* rw- */

#define KSYM_FILTER_ENTRY_LEN (KSYM_NAME_LEN + KSYM_TRACER_OP_LEN + 1)



struct trace_ksym {

	struct hw_breakpoint	*ksym_hbp;
@@ -230,25 +229,33 @@ static ssize_t ksym_trace_filter_read(struct file *filp, char __user *ubuf, 
{

	struct trace_ksym *entry;

	struct hlist_node *node;

	char buf[KSYM_FILTER_ENTRY_LEN * KSYM_TRACER_MAX];

	ssize_t ret, cnt = 0;

	struct trace_seq *s;

	ssize_t cnt = 0;

	int ret;



	s = kmalloc(sizeof(*s), GFP_KERNEL);

	if (!s)

		return -ENOMEM;

	trace_seq_init(s);



	mutex_lock(&ksym_tracer_mutex);



	hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) {

		cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt, "%s:",

				entry->ksym_hbp->info.name);

		ret = trace_seq_printf(s, "%s:", entry->ksym_hbp->info.name);

		if (entry->ksym_hbp->info.type == HW_BREAKPOINT_WRITE)

			cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt,

								"-w-\n");

			ret = trace_seq_puts(s, "-w-\n");

		else if (entry->ksym_hbp->info.type == HW_BREAKPOINT_RW)

			cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt,

								"rw-\n");

			ret = trace_seq_puts(s, "rw-\n");

		WARN_ON_ONCE(!ret);

	}

	ret = simple_read_from_buffer(ubuf, count, ppos, buf, strlen(buf));



	cnt = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);



	mutex_unlock(&ksym_tracer_mutex);



	return ret;

	kfree(s);



	return cnt;

}



static ssize_t ksym_trace_filter_write(struct file *file,