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From: Johannes Berg <johannes@sipsolutions.net>
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
Date: Thu, 23 Jul 2020 22:06:46 +0200	[thread overview]
Message-ID: <ce380ea1fd1f5db40a92f67673f070a1f88eee50.camel@sipsolutions.net> (raw)
In-Reply-To: <003201d6611e$c54a1c90$4fde55b0$@codeaurora.org>

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?

johannes


  reply	other threads:[~2020-07-23 20:07 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 [this message]
2020-07-24  6:21         ` Rakesh Pillai
2020-07-26 16:19         ` Rakesh Pillai
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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