Merge branch 'netconsole-add-support-for-userdata-release'

Breno Leitao says:

====================
netconsole: Add support for userdata release

I am submitting a series of patches that introduce a new feature for the
netconsole subsystem, specifically the addition of the 'release' field
to the sysdata structure. This feature allows the kernel release/version
to be appended to the userdata dictionary in every message sent,
enhancing the information available for debugging and monitoring
purposes.

This complements the already supported release prepend feature, which
was added some time ago. The release prepend appends the release
information at the message header, which is not ideal for two reasons:

 1) It is difficult to determine if a message includes this information,
    making it hard and resource-intensive to parse.

 2) When a message is fragmented, the release information is appended to
    every message fragment, consuming valuable space in the packet.

The "release prepend" feature was created before the concept of userdata
and sysdata. Now that this format has proven successful, we are
implementing the release feature as part of this enhanced structure.

This patch series aims to improve the netconsole subsystem by providing
a more efficient and user-friendly way to include kernel release
information in messages. I believe these changes will significantly aid
in system analysis and troubleshooting.

Suggested-by: Manu Bretelle <chantr4@gmail.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
====================

Link: https://patch.msgid.link/20250314-netcons_release-v1-0-07979c4b86af@debian.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 67 insertions, 4 deletions

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 43757b5c0216..4289ccd3e41b 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -106,6 +106,8 @@ enum sysdata_feature {
 	SYSDATA_CPU_NR = BIT(0),
 	/* Populate the task name (as in current->comm) in sysdata */
 	SYSDATA_TASKNAME = BIT(1),
+	/* Kernel release/version as part of sysdata */
+	SYSDATA_RELEASE = BIT(2),
 };
 
 /**
@@ -440,6 +442,19 @@ static ssize_t sysdata_taskname_enabled_show(struct config_item *item,
 	return sysfs_emit(buf, "%d\n", taskname_enabled);
 }
 
+static ssize_t sysdata_release_enabled_show(struct config_item *item,
+					    char *buf)
+{
+	struct netconsole_target *nt = to_target(item->ci_parent);
+	bool release_enabled;
+
+	mutex_lock(&dynamic_netconsole_mutex);
+	release_enabled = !!(nt->sysdata_fields & SYSDATA_TASKNAME);
+	mutex_unlock(&dynamic_netconsole_mutex);
+
+	return sysfs_emit(buf, "%d\n", release_enabled);
+}
+
 /*
  * This one is special -- targets created through the configfs interface
  * are not enabled (and the corresponding netpoll activated) by default.
@@ -719,6 +734,8 @@ static size_t count_extradata_entries(struct netconsole_target *nt)
 		entries += 1;
 	if (nt->sysdata_fields & SYSDATA_TASKNAME)
 		entries += 1;
+	if (nt->sysdata_fields & SYSDATA_RELEASE)
+		entries += 1;
 
 	return entries;
 }
@@ -855,6 +872,40 @@ static void disable_sysdata_feature(struct netconsole_target *nt,
 	nt->extradata_complete[nt->userdata_length] = 0;
 }
 
+static ssize_t sysdata_release_enabled_store(struct config_item *item,
+					     const char *buf, size_t count)
+{
+	struct netconsole_target *nt = to_target(item->ci_parent);
+	bool release_enabled, curr;
+	ssize_t ret;
+
+	ret = kstrtobool(buf, &release_enabled);
+	if (ret)
+		return ret;
+
+	mutex_lock(&dynamic_netconsole_mutex);
+	curr = !!(nt->sysdata_fields & SYSDATA_RELEASE);
+	if (release_enabled == curr)
+		goto unlock_ok;
+
+	if (release_enabled &&
+	    count_extradata_entries(nt) >= MAX_EXTRADATA_ITEMS) {
+		ret = -ENOSPC;
+		goto unlock;
+	}
+
+	if (release_enabled)
+		nt->sysdata_fields |= SYSDATA_RELEASE;
+	else
+		disable_sysdata_feature(nt, SYSDATA_RELEASE);
+
+unlock_ok:
+	ret = strnlen(buf, count);
+unlock:
+	mutex_unlock(&dynamic_netconsole_mutex);
+	return ret;
+}
+
 static ssize_t sysdata_taskname_enabled_store(struct config_item *item,
 					      const char *buf, size_t count)
 {
@@ -935,6 +986,7 @@ unlock:
 CONFIGFS_ATTR(userdatum_, value);
 CONFIGFS_ATTR(sysdata_, cpu_nr_enabled);
 CONFIGFS_ATTR(sysdata_, taskname_enabled);
+CONFIGFS_ATTR(sysdata_, release_enabled);
 
 static struct configfs_attribute *userdatum_attrs[] = {
 	&userdatum_attr_value,
@@ -996,6 +1048,7 @@ static void userdatum_drop(struct config_group *group, struct config_item *item)
 static struct configfs_attribute *userdata_attrs[] = {
 	&sysdata_attr_cpu_nr_enabled,
 	&sysdata_attr_taskname_enabled,
+	&sysdata_attr_release_enabled,
 	NULL,
 };
 
@@ -1171,7 +1224,7 @@ static void populate_configfs_item(struct netconsole_target *nt,
 	init_target_config_group(nt, target_name);
 }
 
-static int append_cpu_nr(struct netconsole_target *nt, int offset)
+static int sysdata_append_cpu_nr(struct netconsole_target *nt, int offset)
 {
 	/* Append cpu=%d at extradata_complete after userdata str */
 	return scnprintf(&nt->extradata_complete[offset],
@@ -1179,12 +1232,20 @@ static int append_cpu_nr(struct netconsole_target *nt, int offset)
 			 raw_smp_processor_id());
 }
 
-static int append_taskname(struct netconsole_target *nt, int offset)
+static int sysdata_append_taskname(struct netconsole_target *nt, int offset)
 {
 	return scnprintf(&nt->extradata_complete[offset],
 			 MAX_EXTRADATA_ENTRY_LEN, " taskname=%s\n",
 			 current->comm);
 }
+
+static int sysdata_append_release(struct netconsole_target *nt, int offset)
+{
+	return scnprintf(&nt->extradata_complete[offset],
+			 MAX_EXTRADATA_ENTRY_LEN, " release=%s\n",
+			 init_utsname()->release);
+}
+
 /*
  * prepare_extradata - append sysdata at extradata_complete in runtime
  * @nt: target to send message to
@@ -1203,9 +1264,11 @@ static int prepare_extradata(struct netconsole_target *nt)
 		goto out;
 
 	if (nt->sysdata_fields & SYSDATA_CPU_NR)
-		extradata_len += append_cpu_nr(nt, extradata_len);
+		extradata_len += sysdata_append_cpu_nr(nt, extradata_len);
 	if (nt->sysdata_fields & SYSDATA_TASKNAME)
-		extradata_len += append_taskname(nt, extradata_len);
+		extradata_len += sysdata_append_taskname(nt, extradata_len);
+	if (nt->sysdata_fields & SYSDATA_RELEASE)
+		extradata_len += sysdata_append_release(nt, extradata_len);
 
 	WARN_ON_ONCE(extradata_len >
 		     MAX_EXTRADATA_ENTRY_LEN * MAX_EXTRADATA_ITEMS);