The per-target token bucket has no interface, so every target is still
unlimited.
Expose the interval as ratelimit_interval_ms through configfs. It
defaults to zero, so a target stays unlimited until an administrator
sets one.
The write restarts the interval instead of only publishing the new
value. A target is configured while it floods, by which point the
bucket is empty, and ___ratelimit() only refills it once the interval
it was set with has elapsed.
Reject more than INT_MAX milliseconds. msecs_to_jiffies() saturates at
MAX_JIFFY_OFFSET, which is below INT_MAX on 32-bit, so checking only
the jiffies value would take a write there that a 64-bit kernel turns
down.
Reviewed-by: Gustavo Luiz Duarte <gustavold@gmail.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
---
drivers/net/netconsole.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 3e4495c1cab182..69acf2c5c6b063 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -970,6 +970,14 @@ static ssize_t transmit_errors_show(struct config_item *item, char *buf)
return sysfs_emit(buf, "%llu\n", xmit_drop_count + enomem_count);
}
+static ssize_t ratelimit_interval_ms_show(struct config_item *item, char *buf)
+{
+ struct netconsole_target *nt = to_target(item);
+
+ return sysfs_emit(buf, "%u\n",
+ jiffies_to_msecs(READ_ONCE(nt->ratelimit.interval)));
+}
+
/* configfs helper to display if cpu_nr sysdata feature is enabled */
static ssize_t sysdata_cpu_nr_enabled_show(struct config_item *item, char *buf)
{@@ -1359,6 +1367,35 @@ static ssize_t remote_mac_store(struct config_item *item, const char *buf,
return ret;
}
+static ssize_t ratelimit_interval_ms_store(struct config_item *item,
+ const char *buf, size_t count)
+{
+ struct netconsole_target *nt = to_target(item);
+ unsigned int interval;
+ unsigned long jifs;
+ ssize_t ret;
+
+ ret = kstrtouint(buf, 10, &interval);
+ if (ret)
+ return ret;
+
+ /* msecs_to_jiffies() saturates below INT_MAX on 32-bit, so the
+ * jiffies value alone does not bound what userspace wrote.
+ */
+ jifs = msecs_to_jiffies(interval);
+ if (interval > INT_MAX || jifs > INT_MAX)
+ return -ERANGE;
+
+ /* Restart the interval, so a target that is already flooding picks
+ * the new limit up now rather than at the next refill.
+ */
+ dynamic_netconsole_mutex_lock();
+ ratelimit_state_reset_interval(&nt->ratelimit, jifs);
+ dynamic_netconsole_mutex_unlock();
+
+ return count;
+}
+
struct userdatum {
struct config_item item;
char value[MAX_EXTRADATA_VALUE_LEN];@@ -1723,6 +1760,7 @@ CONFIGFS_ATTR_RO(, local_mac);
CONFIGFS_ATTR(, remote_mac);
CONFIGFS_ATTR(, release);
CONFIGFS_ATTR_RO(, transmit_errors);
+CONFIGFS_ATTR(, ratelimit_interval_ms);
static struct configfs_attribute *netconsole_target_attrs[] = {
&attr_enabled,@@ -1736,6 +1774,7 @@ static struct configfs_attribute *netconsole_target_attrs[] = {
&attr_local_mac,
&attr_remote_mac,
&attr_transmit_errors,
+ &attr_ratelimit_interval_ms,
NULL,
};
--
2.53.0-Meta