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SubjectRe: [PATCH v2 1/1] Driver for Beckhoff CX5020 EtherCAT master module.
From
From: Darek Marcinkiewicz <reksio@newterm.pl>
Date: Mon, 28 Apr 2014 07:36:58 +0200

> +void *ec_bh_alloc_dma_mem(struct bh_priv *priv,
> + int channel,
> + u8 **buf,
> + dma_addr_t *phys,
> + dma_addr_t *phys_buf,
> + size_t *len) {
> + u32 mask;
> + int offset = channel * DMA_CHAN_SIZE + DMA_CHAN_OFFSET;
> +
> + iowrite32(0xffffffff, priv->dma_io + offset);
> +
> + mask = ioread32(priv->dma_io + offset);
> + mask &= 0xfffffffc;
> + dev_info(PRIV_TO_DEV(priv),
> + "Read mask %x for channel %d\n",
> + mask, channel);
> + *len = ~mask + 1;
> +
> + dev_info(PRIV_TO_DEV(priv),
> + "Allocating %d bytes for channel %d",
> + (int)*len, channel);
> + *buf = pci_alloc_consistent(priv->dev,
> + *len * 2,
> + phys_buf);

This is really confusing, the log message says that it allocates
"*len" bytes, but actually you are allocating "*len * 2" bytes as
per the arguments you are passing into pci_alloc_consistent.

Either one or the other is wrong, and if "*len * 2" is the correct
size then it should be explained why you're doubling this value
but providing just plain "*len" to the caller.

All of these *len values seem to be doubled over and over again,
in the memset() calls, in the pci_free_consistent() calls during
resource release on probe error and driver shutdown.

Why not just assign X * 2 to *len and get rid of this doubling all
over the place?


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