[v5,05/45] xenbus/backend: dynamically allocate the xen-backend shrinker

Commit Message

Qi Zheng Aug. 24, 2023, 3:42 a.m. UTC

Use new APIs to dynamically allocate the xen-backend shrinker.

Signed-off-by: Qi Zheng <[e-mail]>
Reviewed-by: Muchun Song <[e-mail]>
CC: Juergen Gross <[e-mail]>
CC: Stefano Stabellini <[e-mail]>
CC: Oleksandr Tyshchenko <[e-mail]>
CC: [e-mail]
---
 drivers/xen/xenbus/xenbus_probe_backend.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

Comments

Juergen Gross Aug. 24, 2023, 6 a.m. UTC | #1

On 24.08.23 05:42, Qi Zheng wrote:
> Use new APIs to dynamically allocate the xen-backend shrinker.
> 
> Signed-off-by: Qi Zheng <[e-mail]>
> Reviewed-by: Muchun Song <[e-mail]>
> CC: Juergen Gross <[e-mail]>
> CC: Stefano Stabellini <[e-mail]>
> CC: Oleksandr Tyshchenko <[e-mail]>
> CC: [e-mail]

Acked-by: Juergen Gross <[e-mail]>

Just one note: it seems as if most users will set seeks to DEFAULT_SEEKS.
Wouldn't it be better to do this in shrinker_alloc() and let only callers
who want a different value overwrite that?


Juergen

Qi Zheng Aug. 24, 2023, 6:24 a.m. UTC | #2

Hi Juergen,

On 2023/8/24 14:00, Juergen Gross wrote:
> On 24.08.23 05:42, Qi Zheng wrote:
>> Use new APIs to dynamically allocate the xen-backend shrinker.
>>
>> Signed-off-by: Qi Zheng <[e-mail]>
>> Reviewed-by: Muchun Song <[e-mail]>
>> CC: Juergen Gross <[e-mail]>
>> CC: Stefano Stabellini <[e-mail]>
>> CC: Oleksandr Tyshchenko <[e-mail]>
>> CC: [e-mail]
> 
> Acked-by: Juergen Gross <[e-mail]>

Thanks for your review!

> 
> Just one note: it seems as if most users will set seeks to DEFAULT_SEEKS.
> Wouldn't it be better to do this in shrinker_alloc() and let only callers
> who want a different value overwrite that?

I think it makes sense, will do.

Thanks,
Qi

> 
> 
> Juergen

Patch

diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c
index da96c260e26b..929c41a5ccee 100644
--- a/drivers/xen/xenbus/xenbus_probe_backend.c
+++ b/drivers/xen/xenbus/xenbus_probe_backend.c
@@ -284,13 +284,9 @@  static unsigned long backend_shrink_memory_count(struct shrinker *shrinker,
 	return 0;
 }
 
-static struct shrinker backend_memory_shrinker = {
-	.count_objects = backend_shrink_memory_count,
-	.seeks = DEFAULT_SEEKS,
-};
-
 static int __init xenbus_probe_backend_init(void)
 {
+	struct shrinker *backend_memory_shrinker;
 	static struct notifier_block xenstore_notifier = {
 		.notifier_call = backend_probe_and_watch
 	};
@@ -305,8 +301,16 @@  static int __init xenbus_probe_backend_init(void)
 
 	register_xenstore_notifier(&xenstore_notifier);
 
-	if (register_shrinker(&backend_memory_shrinker, "xen-backend"))
-		pr_warn("shrinker registration failed\n");
+	backend_memory_shrinker = shrinker_alloc(0, "xen-backend");
+	if (!backend_memory_shrinker) {
+		pr_warn("shrinker allocation failed\n");
+		return 0;
+	}
+
+	backend_memory_shrinker->count_objects = backend_shrink_memory_count;
+	backend_memory_shrinker->seeks = DEFAULT_SEEKS;
+
+	shrinker_register(backend_memory_shrinker);
 
 	return 0;
 }