netdev - Re: [PATCH] Improve Atheros ethernet driver not to do order 4 GFP

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Date:	Thu, 3 Dec 2015 16:59:24 +0100
From:	Pavel Machek <pavel@....cz>
To:	David Miller <davem@...emloft.net>
Cc:	eric.dumazet@...il.com, 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] Improve Atheros ethernet driver not to do order 4
 GFP_ATOMIC allocation

On Tue 2015-12-01 15:36:28, David Miller wrote:
> From: Eric Dumazet <eric.dumazet@...il.com>
> Date: Mon, 30 Nov 2015 09:58:23 -0800
> 
> > On Sat, 2015-11-28 at 15:51 +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.
> >>     
> >> 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 memmory for DMA buffer\n");
> >>  		goto err_nomem;
> >>  	}
> >>  	memset(ring_header->desc, 0, ring_header->size);
> >> 
> > 
> > It seems there is a missed opportunity to get rid of the memset() here,
> > by adding __GFP_ZERO to the dma_alloc_coherent() GFP_KERNEL mask,
> > or simply using dma_zalloc_coherent()
> 
> Also, the Subject line needs to be adjusted.  The proper format for
> the Subject line is:
> 
> 	[PATCH $TREE] $subsystem: $description.
> 
> Where "$TREE" is either 'net' or 'net-next', $subsystem is the lowercase
> name of the driver (here 'atl1c') and then a colon, and then a space, and
> then the single-line description.

Done, thanks.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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