[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 | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
Comments
On Mon, Oct 02, 2023 at 08:53:48AM -0700, Breno Leitao wrote:
> 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 | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
> index b68456054a0c..6235f56dc652 100644
> --- a/drivers/net/netconsole.c
> +++ b/drivers/net/netconsole.c
> @@ -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 +712,13 @@ static struct config_item *make_netconsole_target(struct config_group *group,
> struct netconsole_target *nt;
> unsigned long flags;
>
> + /* Checking if there is a target created populated at boot time */
Perhaps a little clearer:
```
/* 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, DEFAULT_TARGET_NAME, strlen(DEFAULT_TARGET_NAME))) {
> + nt = find_cmdline_target(name);
> + if (nt)
> + return &nt->item;
> + }
> +
Thanks,
Joel
@@ -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 +712,13 @@ static struct config_item *make_netconsole_target(struct config_group *group,
struct netconsole_target *nt;
unsigned long flags;
+ /* Checking if there is a target created populated at boot time */
+ if (!strncmp(name, DEFAULT_TARGET_NAME, strlen(DEFAULT_TARGET_NAME))) {
+ nt = find_cmdline_target(name);
+ if (nt)
+ return &nt->item;
+ }
+
nt = alloc_and_init();
if (!nt)
return ERR_PTR(-ENOMEM);