mm/shrinker.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)
Use guard(mutex) to automatically handle shrinker_mutex locking and
unlocking in shrinker_memcg_alloc(). This removes the explicit
mutex_unlock() call, the goto-based error path, and the redundant
ret variable, resulting in cleaner and more concise code.
v2:
- Drop unused 'ret' variable to avoid compiler warning (Muchun Song).
Signed-off-by: wangxuewen <wangxuewen@kylinos.cn>
---
mm/shrinker.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/mm/shrinker.c b/mm/shrinker.c
index 76b3f750cf65..cb03fbecc75d 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -215,29 +215,26 @@ static DEFINE_IDR(shrinker_idr);
static int shrinker_memcg_alloc(struct shrinker *shrinker)
{
- int id, ret = -ENOMEM;
+ int id;
if (mem_cgroup_disabled())
return -ENOSYS;
if (mem_cgroup_kmem_disabled() && !(shrinker->flags & SHRINKER_NONSLAB))
return -ENOSYS;
- mutex_lock(&shrinker_mutex);
+ guard(mutex)(&shrinker_mutex);
id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);
if (id < 0)
- goto unlock;
+ return id;
if (id >= shrinker_nr_max) {
if (expand_shrinker_info(id)) {
idr_remove(&shrinker_idr, id);
- goto unlock;
+ return -ENOMEM;
}
}
shrinker->id = id;
- ret = 0;
-unlock:
- mutex_unlock(&shrinker_mutex);
- return ret;
+ return 0;
}
static void shrinker_memcg_remove(struct shrinker *shrinker)
--
2.25.1On Wed, 13 May 2026 15:52:14 +0800 wangxuewen <18810879172@163.com> wrote:
> Use guard(mutex) to automatically handle shrinker_mutex locking and
> unlocking in shrinker_memcg_alloc(). This removes the explicit
> mutex_unlock() call, the goto-based error path, and the redundant
> ret variable, resulting in cleaner and more concise code.
>
> v2:
> - Drop unused 'ret' variable to avoid compiler warning (Muchun Song).
Patch changelog should go to commentary area [1]. Also adding links to
previous versions would be helpful.
>
> Signed-off-by: wangxuewen <wangxuewen@kylinos.cn>
> ---
> mm/shrinker.c | 13 +++++--------
> 1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/mm/shrinker.c b/mm/shrinker.c
> index 76b3f750cf65..cb03fbecc75d 100644
> --- a/mm/shrinker.c
> +++ b/mm/shrinker.c
> @@ -215,29 +215,26 @@ static DEFINE_IDR(shrinker_idr);
>
> static int shrinker_memcg_alloc(struct shrinker *shrinker)
> {
> - int id, ret = -ENOMEM;
> + int id;
>
> if (mem_cgroup_disabled())
> return -ENOSYS;
> if (mem_cgroup_kmem_disabled() && !(shrinker->flags & SHRINKER_NONSLAB))
> return -ENOSYS;
>
> - mutex_lock(&shrinker_mutex);
> + guard(mutex)(&shrinker_mutex);
> id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);
> if (id < 0)
> - goto unlock;
> + return id;
Could this change the return value? This code was always returning -ENOMEM
before, but seems it can now return -ENOSPC? Seems that doesn't matter,
though.
>
> if (id >= shrinker_nr_max) {
> if (expand_shrinker_info(id)) {
> idr_remove(&shrinker_idr, id);
> - goto unlock;
> + return -ENOMEM;
> }
> }
> shrinker->id = id;
> - ret = 0;
> -unlock:
> - mutex_unlock(&shrinker_mutex);
> - return ret;
> + return 0;
> }
[1] https://docs.kernel.org/process/submitting-patches.html#commentary
Thanks,
SJ
[...]
Hi SeongJae,
Thank you for pointing out the patch changelog convention.
I appreciate the feedback and will make sure to follow the rule of
placing version changelogs after the --- separator in all my future
submissions, as well as adding links to previous versions.
Thanks,
Wang Xuewen
在 2026/5/14 9:12, SeongJae Park 写道:
> On Wed, 13 May 2026 15:52:14 +0800 wangxuewen <18810879172@163.com> wrote:
>
>> Use guard(mutex) to automatically handle shrinker_mutex locking and
>> unlocking in shrinker_memcg_alloc(). This removes the explicit
>> mutex_unlock() call, the goto-based error path, and the redundant
>> ret variable, resulting in cleaner and more concise code.
>>
>> v2:
>> - Drop unused 'ret' variable to avoid compiler warning (Muchun Song).
>
> Patch changelog should go to commentary area [1]. Also adding links to
> previous versions would be helpful.
>
>>
>> Signed-off-by: wangxuewen <wangxuewen@kylinos.cn>
>> ---
>> mm/shrinker.c | 13 +++++--------
>> 1 file changed, 5 insertions(+), 8 deletions(-)
>>
>> diff --git a/mm/shrinker.c b/mm/shrinker.c
>> index 76b3f750cf65..cb03fbecc75d 100644
>> --- a/mm/shrinker.c
>> +++ b/mm/shrinker.c
>> @@ -215,29 +215,26 @@ static DEFINE_IDR(shrinker_idr);
>>
>> static int shrinker_memcg_alloc(struct shrinker *shrinker)
>> {
>> - int id, ret = -ENOMEM;
>> + int id;
>>
>> if (mem_cgroup_disabled())
>> return -ENOSYS;
>> if (mem_cgroup_kmem_disabled() && !(shrinker->flags & SHRINKER_NONSLAB))
>> return -ENOSYS;
>>
>> - mutex_lock(&shrinker_mutex);
>> + guard(mutex)(&shrinker_mutex);
>> id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);
>> if (id < 0)
>> - goto unlock;
>> + return id;
>
> Could this change the return value? This code was always returning -ENOMEM
> before, but seems it can now return -ENOSPC? Seems that doesn't matter,
> though.
>
>>
>> if (id >= shrinker_nr_max) {
>> if (expand_shrinker_info(id)) {
>> idr_remove(&shrinker_idr, id);
>> - goto unlock;
>> + return -ENOMEM;
>> }
>> }
>> shrinker->id = id;
>> - ret = 0;
>> -unlock:
>> - mutex_unlock(&shrinker_mutex);
>> - return ret;
>> + return 0;
>> }
>
> [1] https://docs.kernel.org/process/submitting-patches.html#commentary
>
>
> Thanks,
> SJ
>
> [...]
> On May 13, 2026, at 15:52, wangxuewen <18810879172@163.com> wrote: > > Use guard(mutex) to automatically handle shrinker_mutex locking and > unlocking in shrinker_memcg_alloc(). This removes the explicit > mutex_unlock() call, the goto-based error path, and the redundant > ret variable, resulting in cleaner and more concise code. > > v2: > - Drop unused 'ret' variable to avoid compiler warning (Muchun Song). Changelog should not be placed here. > > Signed-off-by: wangxuewen <wangxuewen@kylinos.cn> > --- The right place. > mm/shrinker.c | 13 +++++-------- > 1 file changed, 5 insertions(+), 8 deletions(-) The change looks good to me. Acked-by: Muchun Song <muchun.song@linux.dev> Thanks.
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