netdev - Re: [PATCH] net: Prevent multiple NAPI instances co-existing in the list

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Date:	Fri, 9 Jan 2015 10:26:48 +0800
From:	Dennis Chen <kernel.org.gnu@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netdev <netdev@...r.kernel.org>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Miller <davem@...emloft.net>
Subject: Re: [PATCH] net: Prevent multiple NAPI instances co-existing in the list

I am very curious about the reason that you're removing the atomic ops
in the stack, what's the benifit?

On Thu, Jan 8, 2015 at 10:51 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Thu, 2015-01-08 at 16:22 +0800, Dennis Chen wrote:
>> Some drivers may clear the NAPI_STATE_SCHED bit upon the state of the
>> NAPI instance after exhaust the budget in the poll function, which
>> will open a window for next device interrupt handler to insert a same
>> instance to the list after calling list_add_tail(&n->poll_list,
>> repoll) if we don't set this bit.
>>
>> Signed-off-by: Dennis Chen <kernel.org.gnu@...il.com>
>> ---
>
>
> Well no.
>
> I am removing some atomic ops in the stack, please do not add new ones,
> especially if no driver is that buggy.
>
> The unlikely() wont help the expensive stuff being done here.
>
>



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