linux-kernel - Re: [PATCH] net: ethernet: ti: cpdma: remove used

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Message-ID: <614baaea-0b60-647b-6000-d4676a94df6b@linaro.org>
Date:	Thu, 4 Aug 2016 18:56:12 +0300
From:	Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
To:	Grygorii Strashko <grygorii.strashko@...com>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	Mugunthan V N <mugunthanvnm@...com>
Cc:	Sekhar Nori <nsekhar@...com>, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org
Subject: Re: [PATCH] net: ethernet: ti: cpdma: remove used_desc counter



On 04.08.16 18:20, Grygorii Strashko wrote:
> The struct cpdma_desc_pool->used_desc field can be safely removed from
> CPDMA driver (and hot patch) because used_descs counter is used just
> for pool consistency check at CPDMA deinitialization and now this
> check can be re-implemnted using gen_pool_size(pool->gen_pool) !=
> gen_pool_avail(pool->gen_pool).
> More over, this will allow to get rid of warnings in
> cpdma_desc_pool_destro()-> WARN_ON(pool->used_desc) which may happen
> because the used_descs is used unprotected, since CPDMA has been
> switched to use genalloc, and may get wrong values on SMP.
>
> Hence, remove used_desc from struct cpdma_desc_pool.
>
> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com

Reviewed-by: Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>

> ---
>  drivers/net/ethernet/ti/davinci_cpdma.c | 18 +++++++-----------
>  1 file changed, 7 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c b/drivers/net/ethernet/ti/davinci_cpdma.c
> index 19e5f32..cf72b33 100644
> --- a/drivers/net/ethernet/ti/davinci_cpdma.c
> +++ b/drivers/net/ethernet/ti/davinci_cpdma.c
> @@ -86,7 +86,7 @@ struct cpdma_desc_pool {
>  	void __iomem		*iomap;		/* ioremap map */
>  	void			*cpumap;	/* dma_alloc map */
>  	int			desc_size, mem_size;
> -	int			num_desc, used_desc;
> +	int			num_desc;
>  	struct device		*dev;
>  	struct gen_pool		*gen_pool;
>  };
> @@ -148,7 +148,10 @@ static void cpdma_desc_pool_destroy(struct cpdma_desc_pool *pool)
>  	if (!pool)
>  		return;
>
> -	WARN_ON(pool->used_desc);
> +	WARN(gen_pool_size(pool->gen_pool) != gen_pool_avail(pool->gen_pool),
> +	     "cpdma_desc_pool size %d != avail %d",
> +	     gen_pool_size(pool->gen_pool),
> +	     gen_pool_avail(pool->gen_pool));
>  	if (pool->cpumap)
>  		dma_free_coherent(pool->dev, pool->mem_size, pool->cpumap,
>  				  pool->phys);
> @@ -232,21 +235,14 @@ desc_from_phys(struct cpdma_desc_pool *pool, dma_addr_t dma)
>  static struct cpdma_desc __iomem *
>  cpdma_desc_alloc(struct cpdma_desc_pool *pool)
>  {
> -	struct cpdma_desc __iomem *desc = NULL;
> -
> -	desc = (struct cpdma_desc __iomem *)gen_pool_alloc(pool->gen_pool,
> -							   pool->desc_size);
> -	if (desc)
> -		pool->used_desc++;
> -
> -	return desc;
> +	return (struct cpdma_desc __iomem *)
> +		gen_pool_alloc(pool->gen_pool, pool->desc_size);
>  }
>
>  static void cpdma_desc_free(struct cpdma_desc_pool *pool,
>  			    struct cpdma_desc __iomem *desc, int num_desc)
>  {
>  	gen_pool_free(pool->gen_pool, (unsigned long)desc, pool->desc_size);
> -	pool->used_desc--;
>  }
>
>  struct cpdma_ctlr *cpdma_ctlr_create(struct cpdma_params *params)
>

-- 
Regards,
Ivan Khoronzhuk