2023-04-17 19:21:17

by SeongJae Park

Subject: [PATCH v4 0/2] mm/slab: trivial fixup for SLAB_TYPESAFE_BY_RCU example code snippet

Changes from v3
(https://lore.kernel.org/linux-mm/[email protected]/)
- Yet more wordsmith of the second patch's commit message
(Matthew Wilcox)

Changes from v2
(https://lore.kernel.org/linux-mm/[email protected]/)
- Wordsmith commit message of the second patch (Valstimil Babka)

Changes from v1
(https://lore.kernel.org/linux-mm/[email protected]/)
- Update label (s/again/begin/) correctly (Matthew Wilcox)
- Add missed rcu_read_unlock()

This patchset is for trivial fixup for SLAB_TYPESAFE_BY_RCU example code
snippet, namely adding missed semicolon and breaking RCU read-side
critical section into smaller ones.

SeongJae Park (2):
mm/slab: add a missing semicolon on SLAB_TYPESAFE_BY_RCU example code
mm/slab: break up RCU readers on SLAB_TYPESAFE_BY_RCU example code

include/linux/slab.h | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--
2.25.1

2023-04-17 19:26:47

by SeongJae Park

Subject: [PATCH v4 2/2] mm/slab: break up RCU readers on SLAB_TYPESAFE_BY_RCU example code

The SLAB_TYPESAFE_BY_RCU example code snippet uses a single RCU
read-side critical section for retries.
'Documentation/RCU/rculist_nulls.rst' has similar example code snippet,
and commit da82af04352b ("doc: Update and wordsmith rculist_nulls.rst")
broke it up. Apply the change to SLAB_TYPESAFE_BY_RCU example code
snippet, too.

Signed-off-by: SeongJae Park <[email protected]>
---
include/linux/slab.h | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index b18e56c6f06c..6acf1b7c6551 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -53,16 +53,18 @@
* stays valid, the trick to using this is relying on an independent
* object validation pass. Something like:
*
+ * begin:
* rcu_read_lock();
- * again:
* obj = lockless_lookup(key);
* if (obj) {
* if (!try_get_ref(obj)) // might fail for free objects
- * goto again;
+ * rcu_read_unlock();
+ * goto begin;
*
* if (obj->key != key) { // not the object we expected
* put_ref(obj);
- * goto again;
+ * rcu_read_unlock();
+ * goto begin;
* }
* }
* rcu_read_unlock();
--
2.25.1

2023-04-24 18:41:28

by Paul E. McKenney

Subject: Re: [PATCH v4 2/2] mm/slab: break up RCU readers on SLAB_TYPESAFE_BY_RCU example code

On Mon, Apr 17, 2023 at 07:04:50PM +0000, SeongJae Park wrote:
> The SLAB_TYPESAFE_BY_RCU example code snippet uses a single RCU
> read-side critical section for retries.
> 'Documentation/RCU/rculist_nulls.rst' has similar example code snippet,
> and commit da82af04352b ("doc: Update and wordsmith rculist_nulls.rst")
> broke it up. Apply the change to SLAB_TYPESAFE_BY_RCU example code
> snippet, too.
>
> Signed-off-by: SeongJae Park <[email protected]>

Reviewed-by: Paul E. McKenney <[email protected]>

> ---
> include/linux/slab.h | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index b18e56c6f06c..6acf1b7c6551 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -53,16 +53,18 @@
> * stays valid, the trick to using this is relying on an independent
> * object validation pass. Something like:
> *
> + * begin:
> * rcu_read_lock();
> - * again:
> * obj = lockless_lookup(key);
> * if (obj) {
> * if (!try_get_ref(obj)) // might fail for free objects
> - * goto again;
> + * rcu_read_unlock();
> + * goto begin;
> *
> * if (obj->key != key) { // not the object we expected
> * put_ref(obj);
> - * goto again;
> + * rcu_read_unlock();
> + * goto begin;
> * }
> * }
> * rcu_read_unlock();
> --
> 2.25.1
>

2023-06-07 12:09:21

by Vlastimil Babka

Subject: Re: [PATCH v4 0/2] mm/slab: trivial fixup for SLAB_TYPESAFE_BY_RCU example code snippet

On 4/17/23 21:04, SeongJae Park wrote:
> Changes from v3
> (https://lore.kernel.org/linux-mm/[email protected]/)
> - Yet more wordsmith of the second patch's commit message
> (Matthew Wilcox)
>
> Changes from v2
> (https://lore.kernel.org/linux-mm/[email protected]/)
> - Wordsmith commit message of the second patch (Valstimil Babka)
>
> Changes from v1
> (https://lore.kernel.org/linux-mm/[email protected]/)
> - Update label (s/again/begin/) correctly (Matthew Wilcox)
> - Add missed rcu_read_unlock()
>
> This patchset is for trivial fixup for SLAB_TYPESAFE_BY_RCU example code
> snippet, namely adding missed semicolon and breaking RCU read-side
> critical section into smaller ones.

Oops, almost forgot to merge this, now done, with Paul's R-b's, in
slab/for-6.5/cleanup. Thanks!

> SeongJae Park (2):
> mm/slab: add a missing semicolon on SLAB_TYPESAFE_BY_RCU example code
> mm/slab: break up RCU readers on SLAB_TYPESAFE_BY_RCU example code
>
> include/linux/slab.h | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>