Messages in this thread |  | | From | "Rakesh Pillai" <> | Subject | RE: [RFC 1/7] mac80211: Add check for napi handle before WARN_ON | Date | Fri, 24 Jul 2020 11:51:12 +0530 |
| |
> -----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.
> > johannes
|  |