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SubjectRe: [PATCH 4/6] rionet: add memory access to simulated Ethernet over rapidio
On Tue, 12 May 2009 16:36:01 +0800
Li Yang <leoli@freescale.com> wrote:

> Through the newly added IO memory access of RapidIO, sender can
> write directly to recipient's rx buffer, either by cpu or DMA engine.
>
> ...
>
> +/* Definitions for rionet memory map driver */
> +#define RIONET_DRVID 0x101
> +#define RIONET_MAX_SK_DATA_SIZE 0x1000
> +#define RIONET_MEM_RIO_BASE 0x10000000
> +#define RIONET_TX_RX_BUFF_SIZE (0x1000 * (128 + 128))
> +#define RIONET_QUEUE_NEXT(x) (((x) < 127) ? ((x) + 1) : 0)

References its arg multiple times, hence is buggy or inefficient when
passed an expression with side-effects.

static inline int rionet_queue_next(int x)

would be better. Assuming that some sane identifier is used instead of
"x".

> +#define RIONET_QUEUE_INC(x) (x = RIONET_QUEUE_NEXT(x))

It's pretty ugly to hide an assignment inside a macro like this. Why
not do

foo = rionet_queue_inc(foo);

at the callsites? It makes it much clearer for the reader.


>
> ...
>
> +#ifdef CONFIG_RIONET_MEMMAP
> +static int rio_send_mem(struct sk_buff *skb,
> + struct net_device *ndev, struct rio_dev *rdev)
> +{
> + struct rionet_private *rnet = netdev_priv(ndev);
> + int enqueue, dequeue;
> +
> + if (!rdev)
> + return -EFAULT;

Is that an appropriate error code?

>
> ...
>


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