netdev - Re: [PATCH v4 02/17] octeontx2-pf: Mailbox communication with AF

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Message-ID: <20200123061440.171e93f6@cakuba>
Date:   Thu, 23 Jan 2020 06:14:40 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Sunil Kovvuri <sunil.kovvuri@...il.com>
Cc:     Linux Netdev List <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Michal Kubecek <mkubecek@...e.cz>,
        Sunil Goutham <sgoutham@...vell.com>,
        Geetha sowjanya <gakula@...vell.com>,
        Christina Jacob <cjacob@...vell.com>,
        Subbaraya Sundeep <sbhatta@...vell.com>,
        Aleksey Makarov <amakarov@...vell.com>
Subject: Re: [PATCH v4 02/17] octeontx2-pf: Mailbox communication with AF

On Thu, 23 Jan 2020 00:57:22 +0530, Sunil Kovvuri wrote:
> > I'm slightly concerned about the use of non-iomem helpers like memset
> > and memcpy on what I understand to be IOMEM, and the lack of memory
> > barriers. But then again, I don't know much about iomem_wc(), is this
> > code definitely correct from memory ordering perspective?
> > (The memory barrier in otx2_mbox_msg_send() should probably be just
> > wmb(), syncing with HW is unrelated with SMP.)  
> 
> The mailbox region is a normal memory which is exposed to two devices
> via PCI BARs.
> And the writeq() call (to trigger IRQ) inside otx2_mbox_msg_send() has a wmb().

Oka, fine, if it works it works, I guess.