Re: [PATCH v8 6/9] livepatch: Use kallsyms_on_each_match_symbol() to improve performance

On 2022/11/23 21:28, Petr Mladek wrote:

Hi,

I am sorry for the late review. I have been snowed under another
tasks.

On Wed 2022-11-02 16:49:18, Zhen Lei wrote:

quoted

Based on the test results of kallsyms_on_each_match_symbol() and
kallsyms_on_each_symbol(), the average performance can be improved by
more than 1500 times.

Sounds great.

quoted

--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c

@@ -153,6 +153,24 @@ static int klp_find_callback(void *data, const char *name,
 	return 0;
 }
 
+static int klp_match_callback(void *data, unsigned long addr)
+{
+	struct klp_find_arg *args = data;
+
+	args->addr = addr;
+	args->count++;
+
+	/*
+	 * Finish the search when the symbol is found for the desired position
+	 * or the position is not defined for a non-unique symbol.
+	 */
+	if ((args->pos && (args->count == args->pos)) ||
+	    (!args->pos && (args->count > 1)))
+		return 1;
+
+	return 0;

This duplicates most of the klp_find_callback(). Please, call this
new function in klp_find_callback() instead of the duplicated code.
I mean to do:

static int klp_find_callback(void *data, const char *name, unsigned long addr)
{
	struct klp_find_arg *args = data;

	if (strcmp(args->name, name))
		return 0;

	return klp_match_callback(data, addr);
}

Good idea. But these patches have been merged into linux-next, how about I post
a new cleanup patch after v6.2-rc1?

Otherwise, it looks good.

Best Regards,
Petr
.

-- 
Regards,
  Zhen Lei