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Message-Id: <20251202-configfs_netcon-v1-2-b4738ead8ee8@debian.org>
Date: Tue, 02 Dec 2025 07:29:02 -0800
From: Breno Leitao <leitao@...ian.org>
To: Andreas Hindborg <a.hindborg@...nel.org>,
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>
Cc: Breno Leitao <leitao@...ian.org>, linux-kernel@...r.kernel.org,
hch@...radead.org, jlbec@...lplan.org, linux-fsdevel@...r.kernel.org,
netdev@...r.kernel.org, gustavold@...il.com, asantostc@...il.com,
calvin@...nvd.org, kernel-team@...a.com
Subject: [PATCH RFC 2/2] netconsole: Plug to dynamic configfs item
Convert netconsole to use the new configfs kernel-space item
registration API for command-line configured targets.
Previously, netconsole created boot-time targets by searching for them
when userspace tried to create an item with the a special name. This
approach was fragile and hard for users to deal with.
This change refactors netconsole to:
- Call configfs_register_item() directly from populate_configfs_item()
to properly register boot/module parameter targets.
- Remove the find_cmdline_target() logic and the special handling in
make_netconsole_target() that intercepted userspace operations (aka
the ugly workaround)
This makes the management of netconsole easier, simplifies the code
(removing ~40 lines) and properly separates kernel-created items from
userspace-created items, making the code more maintainable and robust.
Signed-off-by: Breno Leitao <leitao@...ian.org>
---
drivers/net/netconsole.c | 63 +++++++++++++++++++++------------------------------------------
1 file changed, 21 insertions(+), 42 deletions(-)
diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index bb6e03a92956..d3c720a2f9ef 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -225,8 +225,8 @@ static void netconsole_target_put(struct netconsole_target *nt)
{
}
-static void populate_configfs_item(struct netconsole_target *nt,
- int cmdline_count)
+static int populate_configfs_item(struct netconsole_target *nt,
+ int cmdline_count)
{
}
#endif /* CONFIG_NETCONSOLE_DYNAMIC */
@@ -1256,23 +1256,6 @@ static void init_target_config_group(struct netconsole_target *nt,
configfs_add_default_group(&nt->userdata_group, &nt->group);
}
-static struct netconsole_target *find_cmdline_target(const char *name)
-{
- struct netconsole_target *nt, *ret = NULL;
- unsigned long flags;
-
- spin_lock_irqsave(&target_list_lock, flags);
- list_for_each_entry(nt, &target_list, list) {
- if (!strcmp(nt->group.cg_item.ci_name, name)) {
- ret = nt;
- break;
- }
- }
- spin_unlock_irqrestore(&target_list_lock, flags);
-
- return ret;
-}
-
/*
* Group operations and type for netconsole_subsys.
*/
@@ -1283,19 +1266,6 @@ static struct config_group *make_netconsole_target(struct config_group *group,
struct netconsole_target *nt;
unsigned long flags;
- /* Checking if a target by this name was created at boot time. If so,
- * attach a configfs entry to that target. This enables dynamic
- * control.
- */
- if (!strncmp(name, NETCONSOLE_PARAM_TARGET_PREFIX,
- strlen(NETCONSOLE_PARAM_TARGET_PREFIX))) {
- nt = find_cmdline_target(name);
- if (nt) {
- init_target_config_group(nt, name);
- return &nt->group;
- }
- }
-
nt = alloc_and_init();
if (!nt)
return ERR_PTR(-ENOMEM);
@@ -1351,14 +1321,20 @@ static struct configfs_subsystem netconsole_subsys = {
},
};
-static void populate_configfs_item(struct netconsole_target *nt,
- int cmdline_count)
+static int populate_configfs_item(struct netconsole_target *nt,
+ int cmdline_count)
{
char target_name[16];
+ int ret;
snprintf(target_name, sizeof(target_name), "%s%d",
NETCONSOLE_PARAM_TARGET_PREFIX, cmdline_count);
+
init_target_config_group(nt, target_name);
+
+ ret = configfs_register_item(&netconsole_subsys.su_group,
+ &nt->group.cg_item);
+ return ret;
}
static int sysdata_append_cpu_nr(struct netconsole_target *nt, int offset)
@@ -1899,7 +1875,9 @@ static struct netconsole_target *alloc_param_target(char *target_config,
} else {
nt->enabled = true;
}
- populate_configfs_item(nt, cmdline_count);
+ err = populate_configfs_item(nt, cmdline_count);
+ if (err)
+ goto fail;
return nt;
@@ -1911,6 +1889,8 @@ static struct netconsole_target *alloc_param_target(char *target_config,
/* Cleanup netpoll for given target (from boot/module param) and free it */
static void free_param_target(struct netconsole_target *nt)
{
+ if (nt->group.cg_item.ci_dentry)
+ configfs_unregister_item(&nt->group.cg_item);
netpoll_cleanup(&nt->np);
kfree(nt);
}
@@ -1937,6 +1917,10 @@ static int __init init_netconsole(void)
char *target_config;
char *input = config;
+ err = dynamic_netconsole_init();
+ if (err)
+ goto exit;
+
if (strnlen(input, MAX_PARAM_LENGTH)) {
while ((target_config = strsep(&input, ";"))) {
nt = alloc_param_target(target_config, count);
@@ -1966,10 +1950,6 @@ static int __init init_netconsole(void)
if (err)
goto fail;
- err = dynamic_netconsole_init();
- if (err)
- goto undonotifier;
-
if (console_type_needed & CONS_EXTENDED)
register_console(&netconsole_ext);
if (console_type_needed & CONS_BASIC)
@@ -1978,10 +1958,8 @@ static int __init init_netconsole(void)
return err;
-undonotifier:
- unregister_netdevice_notifier(&netconsole_netdev_notifier);
-
fail:
+ dynamic_netconsole_exit();
pr_err("cleaning up\n");
/*
@@ -1993,6 +1971,7 @@ static int __init init_netconsole(void)
list_del(&nt->list);
free_param_target(nt);
}
+exit:
return err;
}
--
2.47.3
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