netdev - Re: [PATCH v4 6/6] net: sh

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Date:	Fri, 18 May 2012 10:44:43 +0900
From:	"Shimoda, Yoshihiro" <yoshihiro.shimoda.uh@...esas.com>
To:	Francois Romieu <romieu@...zoreil.com>
Cc:	netdev <netdev@...r.kernel.org>,
	SH-Linux <linux-sh@...r.kernel.org>
Subject: Re: [PATCH v4 6/6] net: sh_eth: use NAPI

2012/05/17 19:33, Francois Romieu wrote:
> Shimoda, Yoshihiro <yoshihiro.shimoda.uh@...esas.com> :
> [...]
>> diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
>> index c64a31c..edc7dfe 100644
>> --- a/drivers/net/ethernet/renesas/sh_eth.c
>> +++ b/drivers/net/ethernet/renesas/sh_eth.c
> [...]
< snip >
>> @@ -1678,19 +1710,15 @@ static int sh_eth_start_xmit(struct sk_buff *skb, struct net_device *ndev)
>>  	struct sh_eth_private *mdp = netdev_priv(ndev);
>>  	struct sh_eth_txdesc *txdesc;
>>  	u32 entry;
>> -	unsigned long flags;
>>
>> -	spin_lock_irqsave(&mdp->lock, flags);
>>  	if ((mdp->cur_tx - mdp->dirty_tx) >= (mdp->num_tx_ring - 4)) {
>>  		if (!sh_eth_txfree(ndev)) {
> 
> There are now two racing sh_eth_txfree and there is no [PATCH v4 7/6].
> 
> If I may suggest a slightly different approach, I would apply the patch
> below before anything NAPI related:

Thank you very much for the suggestion. I will modify the NAPI patch to fix
the racing using your suggestion.
(Because the original driver (before NAPI) was already locked by mdp->lock
 in sh_eth_interrupt(), I think that the original driver doesn't have the
 racing issue.)

Best regards,
Yoshihiro Shimoda
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