[net-next,v2,2/3] netconsole: Attach cmdline target to dynamic target
Commit Message
Enable the attachment of a dynamic target to the target created during
boot time. The boot-time targets are named as "cmdline\d", where "\d" is
a number starting at 0.
If the user creates a dynamic target named "cmdline0", it will attach to
the first target created at boot time (as defined in the
`netconsole=...` command line argument). `cmdline1` will attach to the
second target and so forth.
If there is no netconsole target created at boot time, then, the target
name could be reused.
Relevant design discussion:
https://lore.kernel.org/all/ZRWRal5bW93px4km@gmail.com/
Suggested-by: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
---
drivers/net/netconsole.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
@@ -685,6 +685,23 @@ static const struct config_item_type netconsole_target_type = {
.ct_owner = THIS_MODULE,
};
+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->item.ci_name, name)) {
+ ret = nt;
+ break;
+ }
+ }
+ spin_unlock_irqrestore(&target_list_lock, flags);
+
+ return ret;
+}
+
/*
* Group operations and type for netconsole_subsys.
*/
@@ -695,6 +712,17 @@ static struct config_item *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_NAME,
+ strlen(NETCONSOLE_PARAM_TARGET_NAME))) {
+ nt = find_cmdline_target(name);
+ if (nt)
+ return &nt->item;
+ }
+
nt = alloc_and_init();
if (!nt)
return ERR_PTR(-ENOMEM);