[PATCH] most: configfs: ignore repeated create_link requests

[Avi Weiss <thnkslprpt@gmail.com>]

mdev_link_create_link_store() adds a link to mdev_link_list even when
create_link is already set. Two writes of 1 for a device that is not
yet present insert the same list node twice, triggering a warning
with CONFIG_DEBUG_LIST or corrupting the list without it.

Skip repeated requests until destroy_link has succeeded, allowing a
later create_link request to create the link again.

Fixes: acdbb8975373 ("staging: most: allow speculative configuration")
Signed-off-by: Avi Weiss <thnkslprpt@gmail.com>
---
 drivers/most/configfs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/most/configfs.c b/drivers/most/configfs.c
index 8f5158d95bc38..73794d2200125 100644
--- a/drivers/most/configfs.c
+++ b/drivers/most/configfs.c
@@ -122,6 +122,8 @@ static ssize_t mdev_link_create_link_store(struct config_item *item,
 		return ret;
 	if (!tmp)
 		return count;
+	if (mdev_link->create_link && !mdev_link->destroy_link)
+		return count;
 	ret = set_config_and_add_link(mdev_link);
 	if (ret && ret != -ENODEV)
 		return ret;

base-commit: 65ba8f34ec886ec72b2c07ddc8cf3d815c32869d
-- 
2.43.0