diff mbox series

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

Message ID 20221102084921.1615-7-thunder.leizhen@huawei.com
State New
Headers
Series kallsyms: Optimizes the performance of lookup symbols |

Commit Message

Zhen Lei Nov. 2, 2022, 8:49 a.m. UTC 
  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.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
---
 kernel/livepatch/core.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

Comments

Petr Mladek Nov. 23, 2022, 1:28 p.m. UTC | #1 
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:
> 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.

> --- 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);
}

Otherwise, it looks good.

Best Regards,
Petr
Zhen Lei Nov. 24, 2022, 2:36 a.m. UTC | #2 
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:
>> 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.
> 
>> --- 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
> .
>
Petr Mladek Nov. 24, 2022, 8:29 a.m. UTC | #3 
On Thu 2022-11-24 10:36:23, Leizhen (ThunderTown) wrote:
> 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:
> >> 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.
> > 
> >> --- 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?

I am fine with it.

Best Regards,
Petr
Luis Chamberlain Dec. 6, 2022, 10:08 p.m. UTC | #4 
On Thu, Nov 24, 2022 at 10:36:23AM +0800, Leizhen (ThunderTown) wrote:
> 
> 
> 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:
> >> 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.
> > 
> >> --- 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?

You can send the cleanup now. The code doesn't change drastically, just
base it on modules-next.

  Luis
Zhen Lei Dec. 7, 2022, 1:30 a.m. UTC | #5 
On 2022/12/7 6:08, Luis Chamberlain wrote:
> On Thu, Nov 24, 2022 at 10:36:23AM +0800, Leizhen (ThunderTown) wrote:
>>
>>
>> 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:
>>>> 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.
>>>
>>>> --- 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?
> 
> You can send the cleanup now. The code doesn't change drastically, just
> base it on modules-next.

OK

> 
>   Luis
> .
>
diff mbox series

Patch

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 9ada0bc5247be5d..50bfc3481a4ee38 100644
--- 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;
+}
+
 static int klp_find_object_symbol(const char *objname, const char *name,
 				  unsigned long sympos, unsigned long *addr)
 {
@@ -167,7 +185,7 @@  static int klp_find_object_symbol(const char *objname, const char *name,
 	if (objname)
 		module_kallsyms_on_each_symbol(klp_find_callback, &args);
 	else
-		kallsyms_on_each_symbol(klp_find_callback, &args);
+		kallsyms_on_each_match_symbol(klp_match_callback, name, &args);
 
 	/*
 	 * Ensure an address was found. If sympos is 0, ensure symbol is unique;