linux-kernel - Re: [PATCH net] atl1c: Improve driver not to do order 4 GFP

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Message-Id: <20151203.123249.2158644928982094593.davem@davemloft.net>
Date:	Thu, 03 Dec 2015 12:32:49 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	pavel@....cz, mhocko@...nel.org, akpm@...l.org,
	linux-kernel@...r.kernel.org, jcliburn@...il.com,
	chris.snook@...il.com, netdev@...r.kernel.org, rjw@...ysocki.net,
	linux-mm@...ck.org, nic-devel@...lcomm.com, ronangeles@...il.com,
	ebiederm@...ssion.com
Subject: Re: [PATCH net] atl1c: Improve driver not to do order 4 GFP_ATOMIC
 allocation

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Thu, 03 Dec 2015 09:17:28 -0800

> On Thu, 2015-12-03 at 16:59 +0100, Pavel Machek wrote:
>> atl1c driver is doing order-4 allocation with GFP_ATOMIC
>> priority. That often breaks  networking after resume. Switch to
>> GFP_KERNEL. Still not ideal, but should be significantly better.
>> 
>> atl1c_setup_ring_resources() is called from .open() function, and
>> already uses GFP_KERNEL, so this change is safe.
>>     
>> Signed-off-by: Pavel Machek <pavel@....cz>
>> 
>> diff --git a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c
>> index 2795d6d..afb71e0 100644
>> --- a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c
>> +++ b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c
>> @@ -1016,10 +1016,10 @@ static int atl1c_setup_ring_resources(struct atl1c_adapter *adapter)
>>  		sizeof(struct atl1c_recv_ret_status) * rx_desc_count +
>>  		8 * 4;
>>  
>> -	ring_header->desc = pci_alloc_consistent(pdev, ring_header->size,
>> -				&ring_header->dma);
>> +	ring_header->desc = dma_alloc_coherent(&pdev->dev, ring_header->size,
>> +					       &ring_header->dma, GFP_KERNEL);
>>  	if (unlikely(!ring_header->desc)) {
>> -		dev_err(&pdev->dev, "pci_alloc_consistend failed\n");
>> +		dev_err(&pdev->dev, "could not get memory for DMA buffer\n");
>>  		goto err_nomem;
>>  	}
>>  	memset(ring_header->desc, 0, ring_header->size);
>> 
>> 
> 
> So this memset() will really require a different patch to get removed ?
> 
> Sigh, not sure why I review patches.

Agreed, please use dma_zalloc_coherent() and kill that memset().

Thanks.
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