Commit 5fbd6cdb authored by Breno Leitao's avatar Breno Leitao Committed by Jakub Kicinski
Browse files

netconsole: Attach cmdline target to dynamic target 

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: default avatarJoel Becker <jlbec@evilplan.org>
Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/20231012111401.333798-4-leitao@debian.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 131eeb45

drivers/net/netconsole.c

+28 −0
Original line number Diff line number Diff line
@@ -629,6 +629,23 @@ 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.

 */
@@ -639,6 +656,17 @@ 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_PREFIX,

		     strlen(NETCONSOLE_PARAM_TARGET_PREFIX))) {

		nt = find_cmdline_target(name);

		if (nt)

			return &nt->item;

	}



	nt = alloc_and_init();

	if (!nt)

		return ERR_PTR(-ENOMEM);