Keep the number of messages dropped since the last report on the target and send it to the receiver as soon as a message gets through again:
netconsole: 45 messages dropped by rate limit netconsole formats that record itself rather than calling printk(), which would feed the console it is currently servicing. Nothing here has a printk sequence number, so the extended header carries a zero. The timestamp comes from local_clock(), the same clock printk stamps its records with, but it is taken when the notice goes out rather than when the message was logged. It can therefore read a few microseconds later than the message it precedes. The notice rides on the next message the bucket lets through, so a target that goes quiet right after a burst of drops only reports them once the host logs again, and a target with ratelimit_burst set to zero never reports at all. Signed-off-by: Breno Leitao <[email protected]> --- drivers/net/netconsole.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 52 insertions(+), 1 deletion(-) diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index 6d60a5188bf13..0af2e5b4335c0 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c @@ -50,6 +50,7 @@ #include <linux/workqueue.h> #include <linux/delay.h> #include <linux/ratelimit.h> +#include <linux/sched/clock.h> MODULE_AUTHOR("Matt Mackall <[email protected]>"); MODULE_DESCRIPTION("Console driver for network interfaces"); @@ -177,6 +178,7 @@ struct netcons_userdata { * @sysdata_fields: Sysdata features enabled. * @msgcounter: Message sent counter. * @ratelimit: Opaque structure to ratelimit messages + * @pending_drops: Messages dropped since the last notice was sent. * @stats: Packet send stats for the target. Used for debugging. * @state: State of the target. * Visible from userspace (read-write). @@ -221,6 +223,7 @@ struct netconsole_target { u32 sysdata_fields; /* protected by target_list_lock */ u32 msgcounter; + u32 pending_drops; struct ratelimit_state ratelimit; #endif struct netconsole_target_stats stats; @@ -297,7 +300,20 @@ static bool netconsole_ratelimited(struct netconsole_target *nt) if (oops_in_progress) return false; - return !__ratelimit(&nt->ratelimit); + if (__ratelimit(&nt->ratelimit)) + return false; + + nt->pending_drops++; + + return true; +} + +static u32 netconsole_take_drops(struct netconsole_target *nt) +{ + u32 drops = nt->pending_drops; + + nt->pending_drops = 0; + return drops; } #else /* !CONFIG_NETCONSOLE_DYNAMIC */ @@ -345,6 +361,11 @@ static bool netconsole_ratelimited(struct netconsole_target *nt) return false; } +static u32 netconsole_take_drops(struct netconsole_target *nt) +{ + return 0; +} + #endif /* CONFIG_NETCONSOLE_DYNAMIC */ /* Check if the target was bound by mac address. */ @@ -2554,6 +2575,34 @@ static void send_msg_udp(struct netconsole_target *nt, const char *msg, } } +static void send_ratelimit_notice(struct netconsole_target *nt, bool extended) +{ + int len = 0; + u64 ts_usec; + u32 drops; + + drops = netconsole_take_drops(nt); + if (!drops) + return; + + if (extended) { + /* append the extended headers */ + if (nt->release) + len = scnprintf(nt->buf, sizeof(nt->buf), "%s,", + init_utsname()->release); + + ts_usec = div_u64(local_clock(), NSEC_PER_USEC); + len += scnprintf(nt->buf + len, sizeof(nt->buf) - len, + "%u,0,%llu,-;", LOGLEVEL_WARNING, ts_usec); + } + + len += scnprintf(nt->buf + len, sizeof(nt->buf) - len, + "netconsole: %u messages dropped by rate limit\n", + drops); + + send_udp(nt, nt->buf, len); +} + /** * netconsole_write - Generic function to send a msg to all targets * @wctxt: nbcon write context @@ -2583,6 +2632,8 @@ static void netconsole_write(struct nbcon_write_context *wctxt, bool extended) if (!nbcon_enter_unsafe(wctxt)) return; + send_ratelimit_notice(nt, extended); + if (extended) send_ext_msg_udp(nt, wctxt); else -- 2.53.0-Meta
