linux-kernel - [PATCH net-next v2 2/5] netconsole: Helper to count number of used entries

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Message-Id: <20250115-netcon_cpu-v2-2-95971b44dc56@debian.org>
Date: Wed, 15 Jan 2025 05:35:19 -0800
From: Breno Leitao <leitao@...ian.org>
To: Andrew Lunn <andrew+netdev@...n.ch>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>, Jonathan Corbet <corbet@....net>, 
 Shuah Khan <shuah@...nel.org>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 Breno Leitao <leitao@...ian.org>, kernel-team@...a.com, max@...sevol.com, 
 thepacketgeek@...il.com
Subject: [PATCH net-next v2 2/5] netconsole: Helper to count number of used
 entries

Add a helper function nr_extradata_entries() to count the number of used
extradata entries in a netconsole target. This refactors the duplicate
code for counting entries into a single function, which will be reused
by upcoming CPU sysdata changes.

The helper uses list_count_nodes() to count the number of children in
the userdata group configfs hierarchy.

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 drivers/net/netconsole.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 5ef069e8277efa87d6f00d08277dcfe97a858cf9..108ec4f836b62860832c601768546c0ecbdb1153 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -659,6 +659,16 @@ static ssize_t remote_ip_store(struct config_item *item, const char *buf,
 	return ret;
 }

+/* Count number of entries we have in extradata.
+ * This is important because the extradata_complete only supports
+ * MAX_EXTRADATA_ITEMS entries. Before enabling any new {user,sys}data
+ * feature, number of entries needs to checked for available space.
+ */
+static size_t count_extradata_entries(struct netconsole_target *nt)
+{
+	return list_count_nodes(&nt->userdata_group.cg_children);
+}
+
 static ssize_t remote_mac_store(struct config_item *item, const char *buf,
 		size_t count)
 {
@@ -808,15 +818,13 @@ static struct config_item *userdatum_make_item(struct config_group *group,
 	struct netconsole_target *nt;
 	struct userdatum *udm;
 	struct userdata *ud;
-	size_t child_count;

 	if (strlen(name) > MAX_EXTRADATA_NAME_LEN)
 		return ERR_PTR(-ENAMETOOLONG);

 	ud = to_userdata(&group->cg_item);
 	nt = userdata_to_target(ud);
-	child_count = list_count_nodes(&nt->userdata_group.cg_children);
-	if (child_count >= MAX_EXTRADATA_ITEMS)
+	if (count_extradata_entries(nt) >= MAX_EXTRADATA_ITEMS)
 		return ERR_PTR(-ENOSPC);

 	udm = kzalloc(sizeof(*udm), GFP_KERNEL);

-- 
2.43.5