linux-kernel - Re: [PATCH 1/3] net: fs_enet: merge NAPI RX and NAPI TX

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Message-ID: <1472044549.14381.73.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Wed, 24 Aug 2016 06:15:49 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Christophe Leroy <christophe.leroy@....fr>
Cc:     Pantelis Antoniou <pantelis.antoniou@...il.com>,
        Vitaly Bordug <vbordug@...mvista.com>, davem@...emloft.net,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH 1/3] net: fs_enet: merge NAPI RX and NAPI TX

On Wed, 2016-08-24 at 06:07 -0700, Eric Dumazet wrote:

> I am afraid you could live lock here on SMP.
> 
> You should make sure you do not loop forever, not assuming cpu is faster
> than NIC.

You are protected by the tx_lock spinlock, but this is fragile as you
could very well remove this spinlock in the future to get lockless
transmit, like many other drivers.