From: "Rakesh Pillai" <pillair@codeaurora.org>
To: "'Johannes Berg'" <johannes@sipsolutions.net>,
<ath10k@lists.infradead.org>
Cc: <linux-wireless@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<kvalo@codeaurora.org>, <davem@davemloft.net>, <kuba@kernel.org>,
<netdev@vger.kernel.org>, <dianders@chromium.org>,
<evgreen@chromium.org>
Subject: RE: [RFC 1/7] mac80211: Add check for napi handle before WARN_ON
Date: Sun, 26 Jul 2020 21:49:51 +0530 [thread overview]
Message-ID: <000e01d66368$9a6ece70$cf4c6b50$@codeaurora.org> (raw)
In-Reply-To:
> -----Original Message-----
> From: Rakesh Pillai <pillair@codeaurora.org>
> Sent: Friday, July 24, 2020 11:51 AM
> To: 'Johannes Berg' <johannes@sipsolutions.net>;
> 'ath10k@lists.infradead.org' <ath10k@lists.infradead.org>
> Cc: 'linux-wireless@vger.kernel.org' <linux-wireless@vger.kernel.org>;
> 'linux-kernel@vger.kernel.org' <linux-kernel@vger.kernel.org>;
> 'kvalo@codeaurora.org' <kvalo@codeaurora.org>; 'davem@davemloft.net'
> <davem@davemloft.net>; 'kuba@kernel.org' <kuba@kernel.org>;
> 'netdev@vger.kernel.org' <netdev@vger.kernel.org>;
> 'dianders@chromium.org' <dianders@chromium.org>;
> 'evgreen@chromium.org' <evgreen@chromium.org>
> Subject: RE: [RFC 1/7] mac80211: Add check for napi handle before
> WARN_ON
>
>
>
> > -----Original Message-----
> > From: Johannes Berg <johannes@sipsolutions.net>
> > Sent: Friday, July 24, 2020 1:37 AM
> > To: Rakesh Pillai <pillair@codeaurora.org>; ath10k@lists.infradead.org
> > Cc: linux-wireless@vger.kernel.org; linux-kernel@vger.kernel.org;
> > kvalo@codeaurora.org; davem@davemloft.net; kuba@kernel.org;
> > netdev@vger.kernel.org; dianders@chromium.org;
> evgreen@chromium.org
> > Subject: Re: [RFC 1/7] mac80211: Add check for napi handle before
> > WARN_ON
> >
> > On Thu, 2020-07-23 at 23:56 +0530, Rakesh Pillai wrote:
> >
> > > > > - WARN_ON_ONCE(softirq_count() == 0);
> > > > > + WARN_ON_ONCE(napi && softirq_count() == 0);
> > > >
> > > > FWIW, I'm pretty sure this is incorrect - we make assumptions on
> > > > softirqs being disabled in mac80211 for serialization and in place of
> > > > some locking, I believe.
> > > >
> > >
> > > I checked this, but let me double confirm.
> > > But after this change, no packet is submitted from driver in a softirq
> > context.
> > > So ideally this should take care of serialization.
> >
> > I'd guess that we have some reliance on BHs already being disabled, for
> > things like u64 sync updates, or whatnot. I mean, we did "rx_ni()" for a
> > reason ... Maybe lockdep can help catch some of the issues.
> >
> > But couldn't you be in a thread and have BHs disabled too?
>
> This would ideally beat the purpose and possibly hurt the other subsystems
> running on the same core.
>
Hi Johannes,
We do have the usage of napi_gro_receive and netif_receive_skb in mac80211.
/* deliver to local stack */
if (rx->napi)
napi_gro_receive(rx->napi, skb);
else
netif_receive_skb(skb);
Also all the rx_handlers are called under the " rx->local->rx_path_lock" lock.
Is the BH disable still required ?
> >
> > johannes
next prev parent reply other threads:[~2020-07-26 16:23 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-21 17:14 [RFC 0/7] Add support to process rx packets in thread Rakesh Pillai
2020-07-21 17:14 ` [RFC 1/7] mac80211: Add check for napi handle before WARN_ON Rakesh Pillai
2020-07-22 12:56 ` Johannes Berg
2020-07-23 18:26 ` Rakesh Pillai
2020-07-23 20:06 ` Johannes Berg
2020-07-24 6:21 ` Rakesh Pillai
2020-07-26 16:19 ` Rakesh Pillai [this message]
2020-07-30 12:40 ` Johannes Berg
2020-07-21 17:14 ` [RFC 2/7] ath10k: Add support to process rx packet in thread Rakesh Pillai
2020-07-21 21:53 ` Rajkumar Manoharan
2020-07-22 12:27 ` Felix Fietkau
2020-07-22 12:55 ` Johannes Berg
2020-07-22 13:00 ` Felix Fietkau
2020-07-23 6:09 ` Rajkumar Manoharan
2021-03-22 23:57 ` Ben Greear
2021-03-23 1:20 ` Brian Norris
2021-03-23 3:01 ` Ben Greear
2021-03-23 7:45 ` Felix Fietkau
2021-03-25 9:45 ` Rakesh Pillai
2021-03-25 10:33 ` Felix Fietkau
2020-07-23 18:25 ` Rakesh Pillai
2020-07-24 23:11 ` Jacob Keller
2020-07-21 17:14 ` [RFC 3/7] ath10k: Add module param to enable rx thread Rakesh Pillai
2020-07-21 17:14 ` [RFC 4/7] ath10k: Do not exhaust budget on process tx completion Rakesh Pillai
2020-07-21 17:14 ` [RFC 5/7] ath10k: Handle the rx packet processing in thread Rakesh Pillai
2020-07-21 17:14 ` [RFC 6/7] ath10k: Add deliver to stack from thread context Rakesh Pillai
2020-07-21 17:14 ` [RFC 7/7] ath10k: Handle rx thread suspend and resume Rakesh Pillai
2020-07-23 23:06 ` Sebastian Gottschall
2020-07-24 6:19 ` Rakesh Pillai
2020-07-21 17:25 ` [RFC 0/7] Add support to process rx packets in thread Andrew Lunn
2020-07-21 18:05 ` Florian Fainelli
2020-07-23 18:21 ` Rakesh Pillai
2020-07-23 19:02 ` Florian Fainelli
2020-07-24 6:20 ` Rakesh Pillai
2020-07-24 22:28 ` Florian Fainelli
2020-07-22 9:12 ` David Laight
2020-07-22 16:20 ` Jakub Kicinski
[not found] ` <20200725081633.7432-1-hdanton@sina.com>
2020-07-25 10:38 ` Sebastian Gottschall
2020-07-25 14:08 ` Sebastian Gottschall
[not found] ` <20200725145728.10556-1-hdanton@sina.com>
2020-07-25 15:41 ` Sebastian Gottschall
2020-07-26 11:16 ` David Laight
2020-07-28 16:59 ` Rakesh Pillai
2020-07-25 17:57 ` Felix Fietkau
[not found] ` <20200726012244.15264-1-hdanton@sina.com>
2020-07-26 8:10 ` Felix Fietkau
[not found] ` <20200726083239.5060-1-hdanton@sina.com>
2020-07-26 8:59 ` Felix Fietkau
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