netdev - Re: [PATCH] net: renesas: ravb: Fix a stuck issue when a lot of frames are received

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Date:   Sun, 9 May 2021 13:21:35 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...il.com>
To:     Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        davem@...emloft.net, kuba@...nel.org
Cc:     netdev@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH] net: renesas: ravb: Fix a stuck issue when a lot of
 frames are received

On 08.05.2021 23:47, Sergei Shtylyov wrote:

>     Posting a review of the already commited (over my head) patch. It would have
> been appropriate if the patch looked OK but it's not. :-/
> 
>> When a lot of frames were received in the short term, the driver
>> caused a stuck of receiving until a new frame was received. For example,
>> the following command from other device could cause this issue.
>>
>>      $ sudo ping -f -l 1000 -c 1000 <this driver's ipaddress>
> 
>     -l is essential here, right?
>     Have you tried testing sh_eth sriver like that, BTW?

    It's driver! :-)

>> The previous code always cleared the interrupt flag of RX but checks
>> the interrupt flags in ravb_poll(). So, ravb_poll() could not call
>> ravb_rx() in the next time until a new RX frame was received if
>> ravb_rx() returned true. To fix the issue, always calls ravb_rx()
>> regardless the interrupt flags condition.
> 
>     That bacially defeats the purpose of IIUC...
                                           ^ NAPI,

    I was sure I typed NAPI here, yet it got lost in the edits. :-)

>> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
>> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
[...]

MBR, Sergei