linux-kernel - Re: [EXT] Re: [4.20 PATCH] Revert "mwifiex: restructure rx_reorder_tbl

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Date:   Tue, 4 Jun 2019 13:57:27 -0700
From:   Brian Norris <briannorris@...omium.org>
To:     Ganapathi Bhat <gbhat@...vell.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Amitkumar Karwar <amitkarwar@...il.com>,
        Nishant Sarmukadam <nishants@...vell.com>,
        Xinming Hu <huxinming820@...il.com>,
        "linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [EXT] Re: [4.20 PATCH] Revert "mwifiex: restructure
 rx_reorder_tbl_lock usage"

Hi Ganapathi,

On Mon, Jun 3, 2019 at 8:04 PM Ganapathi Bhat <gbhat@...vell.com> wrote:
> > There are a few possible ways to handle this:
> > (a) prevent processing softirqs in that context; e.g., with
> >     local_bh_disable(). This seems somewhat of a hack.
> >     (Side note: I think most of the locks in this driver really could be
> >     spin_lock_bh(), not spin_lock_irqsave() -- we don't really care
> >     about hardirq context for 99% of these locks.)
> > (b) restructure so that packet processing (e.g., netif_rx_ni()) is done
> >     outside of the spinlock.
> >
> > It's actually not that hard to do (b). You can just queue your skb's up in a
> > temporary sk_buff_head list and process them all at once after you've
> > finished processing the reorder table. I have a local patch to do this, and I
> > might send it your way if I can give it a bit more testing.
>
> OK; That will be good; We will run a complete test after the patch; (OR we can work on this, share for review);

I gave my work another round of testing and submitted it here:

https://patchwork.kernel.org/cover/10976089/
[PATCH 0/2] mwifiex: spinlock usage improvements

Feel free to give it a spin. It doesn't completely resolve everything
you were trying to fix, but I believe it helps nudge things in the
right direction.

Brian