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From:   Loic Poulain <loic.poulain@linaro.org>
Date:   Fri, 14 Jan 2022 17:03:39 +0100
Message-ID: <CAMZdPi8g2VxBFzS7Lw=TAN_NPQSuzwLuhEGB2akqn-Tjqer7vQ@mail.gmail.com>
Subject: Re: [PATCH] Fix MRU mismatch issue which may lead to data connection lost
To:     Slark Xiao <slark_xiao@163.com>
Cc:     ryazanov.s.a@gmail.com, johannes@sipsolutions.net,
        davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Shujun Wang <wsj20369@163.com>
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On Fri, 14 Jan 2022 at 11:07, Slark Xiao <slark_xiao@163.com> wrote:
>
> In pci_generic.c there is a 'mru_default' in struct mhi_pci_dev_info.
> This value shall be used for whole mhi if it's given a value for a specific product.
> But in function mhi_net_rx_refill_work(), it's still using hard code value MHI_DEFAULT_MRU.
> 'mru_default' shall have higher priority than MHI_DEFAULT_MRU.
> And after checking, this change could help fix a data connection lost issue.

Interesting, not sure why it fixes data issues, since the device
should comply with any size.Can you add a Fixes tag then? and add the
correct [PATCH net] suffix in the subject:
https://www.kernel.org/doc/html/latest/networking/netdev-FAQ.html

With that:

Reviewed-by: Loic Poulain <loic.poulain@linaro.org>

Thanks,
Loic


>
> Signed-off-by: Shujun Wang <wsj20369@163.com>
> Signed-off-by: Slark Xiao <slark_xiao@163.com>
> ---
>  drivers/net/wwan/mhi_wwan_mbim.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wwan/mhi_wwan_mbim.c b/drivers/net/wwan/mhi_wwan_mbim.c
> index 71bf9b4f769f..6872782e8dd8 100644
> --- a/drivers/net/wwan/mhi_wwan_mbim.c
> +++ b/drivers/net/wwan/mhi_wwan_mbim.c
> @@ -385,13 +385,13 @@ static void mhi_net_rx_refill_work(struct work_struct *work)
>         int err;
>
>         while (!mhi_queue_is_full(mdev, DMA_FROM_DEVICE)) {
> -               struct sk_buff *skb = alloc_skb(MHI_DEFAULT_MRU, GFP_KERNEL);
> +               struct sk_buff *skb = alloc_skb(mbim->mru, GFP_KERNEL);
>
>                 if (unlikely(!skb))
>                         break;
>
>                 err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb,
> -                                   MHI_DEFAULT_MRU, MHI_EOT);
> +                                   mbim->mru, MHI_EOT);
>                 if (unlikely(err)) {
>                         kfree_skb(skb);
>                         break;
> --
> 2.25.1
>