> -----Original Message----- > From: Johannes Berg <johannes@xxxxxxxxxxxxxxxx> > Sent: Friday, July 24, 2020 1:37 AM > To: Rakesh Pillai <pillair@xxxxxxxxxxxxxx>; ath10k@xxxxxxxxxxxxxxxxxxx > Cc: linux-wireless@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > kvalo@xxxxxxxxxxxxxx; davem@xxxxxxxxxxxxx; kuba@xxxxxxxxxx; > netdev@xxxxxxxxxxxxxxx; dianders@xxxxxxxxxxxx; evgreen@xxxxxxxxxxxx > 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
