Re: [PATCH 2/2] netcons: Add udp send fail statistics to netconsole
From: Breno Leitao <leitao@debian.org>
Date: 2024-08-27 12:18:21
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On Sat, Aug 24, 2024 at 02:50:24PM -0700, Maksym Kutsevol wrote:
Enhance observability of netconsole. UDP sends can fail. Start tracking at least two failure possibilities: ENOMEM and NET_XMIT_DROP for every target. Stats are exposed via an additional attribute in CONFIGFS. The exposed statistics allows easier debugging of cases when netconsole messages were not seen by receivers, eliminating the guesswork if the sender thinks that messages in question were sent out. Stats are not reset on enable/disable/change remote ip/etc, they belong to the netcons target itself. Signed-off-by: Maksym Kutsevol <redacted>
Would you mind adding a "Reported-by" me in this case? https://lore.kernel.org/all/ZsWoUzyK5du9Ffl+@gmail.com/ (local)
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diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index 9c09293b5258..45c07ec7842d 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c@@ -82,6 +82,13 @@ static DEFINE_SPINLOCK(target_list_lock); */ static struct console netconsole_ext; +#ifdef CONFIG_NETCONSOLE_DYNAMIC +struct netconsole_target_stats { + size_t xmit_drop_count; + size_t enomem_count;
I am looking at other drivers, and they use a specific type for these counters, u64_stats_sync. if it is possible to use this format, then you can leverage the `__u64_stats_update` helpers, and not worry about locking/overflow!?
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@@ -1015,6 +1035,25 @@ static struct notifier_block netconsole_netdev_notifier = { .notifier_call = netconsole_netdev_event, }; +/** + * count_udp_send_stats - Classify netpoll_send_udp result and count errors. + * @nt: target that was sent to + * @result: result of netpoll_send_udp + * + * Takes the result of netpoll_send_udp and classifies the type of error that + * occurred. Increments statistics in nt->stats accordingly. + */ +static void count_udp_send_stats(struct netconsole_target *nt, int result) +{ +#ifdef CONFIG_NETCONSOLE_DYNAMIC + if (result == NET_XMIT_DROP) { + nt->stats.xmit_drop_count++;
If you change the type, you can use the `u64_stats_inc` helper here.
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@@ -1126,7 +1167,11 @@ static void send_ext_msg_udp(struct netconsole_target *nt, const char *msg, this_offset += this_chunk; } - netpoll_send_udp(&nt->np, buf, this_header + this_offset); + count_udp_send_stats(nt, + netpoll_send_udp(&nt->np, + buf, + this_header + this_offset) + );
as Jakub said, this is not a format that is common in the Linux kenrel.