Re: [PATCH] mtd: rawnand: atmel: Unmap streaming DMA mappings

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: <Tudor.Ambarus@microchip.com>
Cc: <richard@nod.at>, <vigneshr@ti.com>, <peda@axentia.se>,
	<Nicolas.Ferre@microchip.com>, <alexandre.belloni@bootlin.com>,
	<Claudiu.Beznea@microchip.com>, <bbrezillon@kernel.org>,
	<linux-mtd@lists.infradead.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, <stable@vger.kernel.org>
Subject: Re: [PATCH] mtd: rawnand: atmel: Unmap streaming DMA mappings
Date: Mon, 19 Sep 2022 17:29:28 +0200	[thread overview]
Message-ID: <20220919172928.6f918ab2@xps-13> (raw)
In-Reply-To: <86158844-b314-bee8-c5b8-0b757c6b6ab0@microchip.com>

Hello Tudor,

Tudor.Ambarus@microchip.com wrote on Wed, 7 Sep 2022 09:06:39 +0000:

> On 7/28/22 10:40, Tudor Ambarus wrote:
> > Every dma_map_single() call should have its dma_unmap_single() counterpart,
> > because the DMA address space is a shared resource and one could render the
> > machine unusable by consuming all DMA addresses.
> > 
> > Cc: stable@vger.kernel.org
> > Fixes: f88fc122cc34 ("mtd: nand: Cleanup/rework the atmel_nand driver")
> > Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
> > ---
> >  drivers/mtd/nand/raw/atmel/nand-controller.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/mtd/nand/raw/atmel/nand-controller.c b/drivers/mtd/nand/raw/atmel/nand-controller.c
> > index 6ef14442c71a..330d2dafdd2d 100644
> > --- a/drivers/mtd/nand/raw/atmel/nand-controller.c
> > +++ b/drivers/mtd/nand/raw/atmel/nand-controller.c
> > @@ -405,6 +405,7 @@ static int atmel_nand_dma_transfer(struct atmel_nand_controller *nc,
> >  
> >  	dma_async_issue_pending(nc->dmac);
> >  	wait_for_completion(&finished);
> > +	dma_unmap_single(nc->dev, buf_dma, len, dir);
> >  
> >  	return 0;
> >    
> 
> Hi, Richard, Miquel,
> 
> Would you please consider to include this patch in your queue?

I'm catching up only now so as we're at -rc6 and I want things to lay a
bit in -next I don't plan to send a Fixes PR, all the fixes
exceptionally will go through the usual PR as anyway they won't be
ready before the merge window opens.

> If yes, please add the following tag, it solves a regression:
> 
> Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se/

Ok.

Thanks,
Miquèl

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