linux-kernel - Re: [PATCH 2/2] tg3: Fix the TX ring stall

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Message-ID: <20231102041045.3103307-1-alexey.pakhunov@spacex.com>
Date:   Wed, 1 Nov 2023 21:10:45 -0700
From:   <alexey.pakhunov@...cex.com>
To:     <michael.chan@...adcom.com>
CC:     <alexey.pakhunov@...cex.com>, <linux-kernel@...r.kernel.org>,
        <mchan@...adcom.com>, <netdev@...r.kernel.org>,
        <prashant@...adcom.com>, <siva.kallam@...adcom.com>,
        <vincent.wong2@...cex.com>
Subject: Re: [PATCH 2/2] tg3: Fix the TX ring stall

Hi,

> Thanks for the patch.  An alternative fix that may be simpler is to
> add a goto after calling tg3_tso_bug().  Something like this:
> 
>         tg3_tso_bug();
>         goto update_tx_mbox;
> ...
> 
> update_tx_mbox:
>         if (!netdev_xmit_more() || netif_xmit_stopped())
>                 tw32_tx_mbox();
> ...

Yes, I considered this approach but in the end it seemed more fragile. All
future updates to tg3_start_xmit() would need to be careful to make sure
all return paths go through "update_tx_mbox". This is much more
straightforward with a separate wrapper function.

The sizes of both patches are roughly the same. The wrapper function
version:

 drivers/net/ethernet/broadcom/tg3.c | 46 +++++++++++++++++++++++++++++++++++-----------
 1 file changed, 35 insertions(+), 11 deletions(-)

The goto version touches four different return paths: three tg3_tso_bug()
calls and the return at the very top of the function:

 drivers/net/ethernet/broadcom/tg3.c | 46 +++++++++++++++++++++++++++++++++-------------
 1 file changed, 33 insertions(+), 13 deletions(-)

Let me re-test the goto version and resubmit it as v2. Please let me know
which version of the patch you prefer more.

Alex.