From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail2.candelatech.com ([208.74.158.173]:37770 "EHLO mail2.candelatech.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751241AbcIOPWj (ORCPT ); Thu, 15 Sep 2016 11:22:39 -0400 Subject: Re: [PATCH v2 04/21] ath10k: rate-limit packet tx errors To: "Valo, Kalle" References: <1462986153-16318-1-git-send-email-greearb@candelatech.com> <1462986153-16318-5-git-send-email-greearb@candelatech.com> <87wpieefr9.fsf@kamboji.qca.qualcomm.com> <57D96669.20209@candelatech.com> <87sht1b6wc.fsf@kamboji.qca.qualcomm.com> Cc: "linux-wireless@vger.kernel.org" , "ath10k@lists.infradead.org" From: Ben Greear Message-ID: (sfid-20160915_172259_466792_C4A2BC0C) Date: Thu, 15 Sep 2016 08:22:37 -0700 MIME-Version: 1.0 In-Reply-To: <87sht1b6wc.fsf@kamboji.qca.qualcomm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 09/15/2016 06:59 AM, Valo, Kalle wrote: > Ben Greear writes: > >> On 09/14/2016 07:07 AM, Valo, Kalle wrote: >>> greearb@candelatech.com writes: >>> >>>> From: Ben Greear >>>> >>>> When firmware crashes, stack can continue to send packets >>>> for a bit, and existing code was spamming logs. >>>> >>>> So, rate-limit the error message for tx failures. >>>> >>>> Signed-off-by: Ben Greear >>>> --- >>>> drivers/net/wireless/ath/ath10k/mac.c | 5 +++-- >>>> 1 file changed, 3 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c >>>> index cd3016d..42cac32 100644 >>>> --- a/drivers/net/wireless/ath/ath10k/mac.c >>>> +++ b/drivers/net/wireless/ath/ath10k/mac.c >>>> @@ -3432,8 +3432,9 @@ static int ath10k_mac_tx_submit(struct ath10k *ar, >>>> } >>>> >>>> if (ret) { >>>> - ath10k_warn(ar, "failed to transmit packet, dropping: %d\n", >>>> - ret); >>>> + if (net_ratelimit()) >>>> + ath10k_warn(ar, "failed to transmit packet, dropping: %d\n", >>>> + ret); >>>> ieee80211_free_txskb(ar->hw, skb); >>>> } >>> >>> ath10k_warn() is already rate limited. If there's something wrong then >>> that function should be fixed, not the callers. >>> >>> void ath10k_warn(struct ath10k *ar, const char *fmt, ...) >>> { >>> struct va_format vaf = { >>> .fmt = fmt, >>> }; >>> va_list args; >>> >>> va_start(args, fmt); >>> vaf.va = &args; >>> dev_warn_ratelimited(ar->dev, "%pV", &vaf); >>> trace_ath10k_log_warn(ar, &vaf); >>> >>> va_end(args); >>> } >> >> The problem with having the ratelimit here is that you may miss >> rare warnings due to a flood of common warnings. >> >> That is why it is still useful to ratelimit potential floods >> of warnings. > > I think this is a common problem in kernel, not specific to ath10k. For > starters you could configure the limits dev_warn_ratelimited() has, not > trying to workaround it in the driver. I will try to explain this once more. If you have the ratelimit in a centralized place, then all code that calls it is rate-limitted with same counter and each call site gets the same priority. One verbose caller can thus disable logs for the much more rare callers. My patch pre-filters one of the verbose callers, which lets other more rare and interesting callers be more likely to print logging messages that are useful for debugging. >> I would like to remove the ratelimit from ath10k_warn eventually. > > I think that's not a good idea, it might cause unnecessary host reboots > in problem cases. Rate limitting the messages is much better option. Ok, but even so, that would be a later patch and that is not a reason to reject the one I posted. For what it is worth, I and my users have been running such a patch for years in various embedded and other systems and it works fine. Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com