From: David Miller <davem@davemloft.net>
To: yoshihiro.shimoda.uh@renesas.com
Cc: netdev@vger.kernel.org, linux-sh@vger.kernel.org
Subject: Re: [PATCH v3 6/6] net: sh_eth: use NAPI
Date: Tue, 15 May 2012 13:05:52 -0400 (EDT) [thread overview]
Message-ID: <20120515.130552.119728053706080493.davem@davemloft.net> (raw)
In-Reply-To: <4FB225F1.20407@renesas.com>
From: "Shimoda, Yoshihiro" <yoshihiro.shimoda.uh@renesas.com>
Date: Tue, 15 May 2012 18:46:25 +0900
> 2012/05/15 14:07, David Miller wrote:
>> From: "Shimoda, Yoshihiro" <yoshihiro.shimoda.uh@renesas.com>
>> Date: Tue, 15 May 2012 13:47:44 +0900
>>
>>> 2012/05/15 7:50, David Miller wrote:
>>>> You need strict synchronization between your TX queueing and TX
>>>> liberation flows. So that queue stop and wake are only performed
>>>> at the correct moment.
>>>
>>> I will add netif_queue_stopped() in the sh_eth_poll().
>>
>> That doesn't fix the bug. What if someone transmits a packet and
>> fills the TX queue between the netif_queue_stopped() test and the
>> call to netif_wake_queue()?
>>
>> Adding another test doesn't create the necessary synchronization.
>>
>
> Thank you for the reply again.
> I will modify the code as the following. Is it correct?
>
> if (txfree_num) {
> netif_tx_lock(ndev);
> if (netif_queue_stopped(ndev))
> netif_wake_queue(ndev);
> netif_tx_unlock(ndev);
> }
Yes, and then you don't need that private lock in the start_xmit()
method at all, since that method runs with the tx_lock held.
next prev parent reply other threads:[~2012-05-15 17:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-14 6:47 [PATCH v3 6/6] net: sh_eth: use NAPI Shimoda, Yoshihiro
2012-05-14 22:50 ` David Miller
2012-05-15 4:47 ` Shimoda, Yoshihiro
2012-05-15 5:07 ` David Miller
2012-05-15 9:46 ` Shimoda, Yoshihiro
2012-05-15 13:43 ` Francois Romieu
2012-05-15 17:05 ` David Miller [this message]
2012-05-15 18:29 ` Francois Romieu
2012-05-16 2:24 ` Shimoda, Yoshihiro
2012-05-16 2:14 ` Shimoda, Yoshihiro
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