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. Signed-off-by: Breno Leitao <[email protected]> --- drivers/net/netconsole.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index c1c92413c0a5c5..d4e3ac272e9b4a 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c @@ -958,6 +958,14 @@ 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) { @@ -1353,6 +1361,35 @@ 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]; @@ -1717,6 +1754,7 @@ 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, @@ -1730,6 +1768,7 @@ 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
