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Message-ID: <20240204232744.91315-7-thepacketgeek@gmail.com>
Date: Sun, 4 Feb 2024 15:27:37 -0800
From: Matthew Wood <thepacketgeek@...il.com>
To: "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>,
netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH net-next v3 6/8] net: netconsole: cache userdata formatted string in netconsole_target
Store a formatted string for userdata that will be appended to netconsole
messages. The string has a capacity of 4KB, as calculated by the userdatum
entry length of 256 bytes and a max of 16 userdata entries.
Update the stored netconsole_target->userdata_complete string with the new
formatted userdata values when a userdatum is created, edited, or
removed. Each userdata entry contains a trailing newline, which will be
formatted as such in netconsole messages::
6.7.0-rc8-virtme,12,500,1646292204,-;test
release=foo
something=bar
6.7.0-rc8-virtme,12,500,1646292204,-;another test
release=foo
something=bar
Enforcement of MAX_USERDATA_ITEMS is done in userdatum_make_item;
update_userdata will not check for this case but will skip any userdata
children over the limit of MAX_USERDATA_ITEMs.
If a userdata entry/dir is created but no value is provided, that entry
will be skipped. This is in part because update_userdata() can't be
called in userdatum_make_item() since the item will not have been added
to the userdata config_group children yet. To preserve the experience of
adding an empty userdata that doesn't show up in the netconsole
messages, purposefully skip empty userdata items even when
update_userdata() can be called.
Co-developed-by: Breno Leitao <leitao@...ian.org>
Signed-off-by: Breno Leitao <leitao@...ian.org>
Signed-off-by: Matthew Wood <thepacketgeek@...il.com>
---
drivers/net/netconsole.c | 61 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 61 insertions(+)
diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 3618b9ebcce4..e4d6ba0b50ef 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -85,6 +85,8 @@ static struct console netconsole_ext;
* @list: Links this target into the target_list.
* @group: Links us into the configfs subsystem hierarchy.
* @userdata_group: Links to the userdata configfs hierarchy
+ * @userdata_complete: Cached, formatted string of append
+ * @userdata_length: String length of userdata_complete
* @enabled: On / off knob to enable / disable target.
* Visible from userspace (read-write).
* We maintain a strict 1:1 correspondence between this and
@@ -109,6 +111,8 @@ struct netconsole_target {
#ifdef CONFIG_NETCONSOLE_DYNAMIC
struct config_group group;
struct config_group userdata_group;
+ char userdata_complete[MAX_USERDATA_ENTRY_LENGTH * MAX_USERDATA_ITEMS];
+ size_t userdata_length;
#endif
bool enabled;
bool extended;
@@ -638,10 +642,48 @@ static ssize_t userdatum_value_show(struct config_item *item, char *buf)
return sysfs_emit(buf, "%s\n", &(to_userdatum(item)->value[0]));
}
+static void update_userdata(struct netconsole_target *nt)
+{
+ int complete_idx = 0, child_count = 0;
+ struct list_head *entry;
+
+ /* Clear the current string in case the last userdatum was deleted */
+ nt->userdata_length = 0;
+ nt->userdata_complete[0] = 0;
+
+ list_for_each(entry, &nt->userdata_group.cg_children) {
+ struct userdatum *udm_item;
+ struct config_item *item;
+
+ if (child_count >= MAX_USERDATA_ITEMS)
+ break;
+ child_count++;
+
+ item = container_of(entry, struct config_item, ci_entry);
+ udm_item = to_userdatum(item);
+
+ /* Skip userdata with no value set */
+ if (strnlen(udm_item->value, MAX_USERDATA_VALUE_LENGTH) == 0)
+ continue;
+
+ /* This doesn't overflow userdata_complete since it will write
+ * one entry length (1/MAX_USERDATA_ITEMS long), entry count is
+ * checked to not exceed MAX items with child_count above
+ */
+ complete_idx += scnprintf(&nt->userdata_complete[complete_idx],
+ MAX_USERDATA_ENTRY_LENGTH, "%s=%s\n",
+ item->ci_name, udm_item->value);
+ }
+ nt->userdata_length = strnlen(nt->userdata_complete,
+ sizeof(nt->userdata_complete));
+}
+
static ssize_t userdatum_value_store(struct config_item *item, const char *buf,
size_t count)
{
struct userdatum *udm = to_userdatum(item);
+ struct netconsole_target *nt;
+ struct userdata *ud;
int ret;
if (count > MAX_USERDATA_VALUE_LENGTH)
@@ -654,6 +696,10 @@ static ssize_t userdatum_value_store(struct config_item *item, const char *buf,
goto out_unlock;
trim_newline(udm->value, sizeof(udm->value));
+ ud = to_userdata(item->ci_parent);
+ nt = userdata_to_target(ud);
+ update_userdata(nt);
+
mutex_unlock(&dynamic_netconsole_mutex);
return count;
out_unlock:
@@ -708,12 +754,27 @@ static struct config_item *userdatum_make_item(struct config_group *group,
return &udm->item;
}
+static void userdatum_drop(struct config_group *group, struct config_item *item)
+{
+ struct netconsole_target *nt;
+ struct userdata *ud;
+
+ ud = to_userdata(&group->cg_item);
+ nt = userdata_to_target(ud);
+
+ mutex_lock(&dynamic_netconsole_mutex);
+ update_userdata(nt);
+ config_item_put(item);
+ mutex_unlock(&dynamic_netconsole_mutex);
+}
+
static struct configfs_attribute *userdata_attrs[] = {
NULL,
};
static struct configfs_group_operations userdata_ops = {
.make_item = userdatum_make_item,
+ .drop_item = userdatum_drop,
};
static struct config_item_type userdata_type = {
--
2.43.0
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