Re: [PATCH v3 33/37] mtd: nand: allocate aligned buffers if NAND_OWN_BUFFERS is unset

[Boris Brezillon]

On Thu, 30 Mar 2017 17:15:04 +0900
Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> wrote:

> Some NAND controllers are using DMA engine requiring a specific
> buffer alignment.  The core provides no guarantee on the nand_buffers
> pointers, which forces some drivers to allocate their own buffers
> and pass the NAND_OWN_BUFFERS flag.
> 
> Rework the nand_buffers allocation logic to allocate each buffer
> independently.  This should make most NAND controllers/DMA engine
> happy, and allow us to get rid of these custom buf allocation in
> NAND controller drivers.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> ---
> 
> Changes in v3:
>   - Reword git-log
> 
> Changes in v2:
>   - Newly added
> 
>  drivers/mtd/nand/nand_base.c | 34 +++++++++++++++++++++++++++-------
>  1 file changed, 27 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index f828ad7..e9d3195 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -4613,13 +4613,25 @@ int nand_scan_tail(struct mtd_info *mtd)
>  	}
>  
>  	if (!(chip->options & NAND_OWN_BUFFERS)) {
> -		nbuf = kzalloc(sizeof(*nbuf) + mtd->writesize
> -				+ mtd->oobsize * 3, GFP_KERNEL);
> +		nbuf = kzalloc(sizeof(*nbuf), GFP_KERNEL);
>  		if (!nbuf)
>  			return -ENOMEM;
> -		nbuf->ecccalc = (uint8_t *)(nbuf + 1);
> -		nbuf->ecccode = nbuf->ecccalc + mtd->oobsize;
> -		nbuf->databuf = nbuf->ecccode + mtd->oobsize;
> +		nbuf->ecccalc = kmalloc(mtd->oobsize, GFP_KERNEL);
> +		if (!nbuf->ecccalc) {
> +			ret = -EINVAL;
> +			goto err_free;

You have a memory leak here, because chip->buffers = nbuf is only done
after all allocations have succeeded.

> +		}
> +		nbuf->ecccode = kmalloc(mtd->oobsize, GFP_KERNEL);
> +		if (!nbuf->ecccode) {
> +			ret = -EINVAL;

			ret = -ENOMEM;

I have the following fixup patch, let me know if you're okay with it
and I'll squash it in the original commit.

Thanks,

Boris

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