Re: [PATCH] mtd: m25p80: consider max message size when use the spi_mem_xx() API

[Boris Brezillon <boris.brezillon@bootlin.com>]

Hi Chuanhua,

On Mon, 20 Aug 2018 17:43:26 +0800
Chuanhua Han <chuanhua.han@nxp.com> wrote:

Subject prefix should be "spi: spi-mem: " not "mtd: m25p80: ", and you
need a commit message explaining what this patch does and why it's
needed.

> Signed-off-by: Chuanhua Han <chuanhua.han@nxp.com>

Fixes: c36ff266dc82 ("spi: Extend the core to ease integration of SPI memory controllers")
Cc: <stable@vger.kernel.org>

> ---
> Changes in v2:
> 	- Place the adjusted transfer bytes code in spi_mem_adjust_op_size()
> 	and  check spi_max_message_size(mem->spi) value before subtracting 
> 	opcode, addr and dummy bytes.
> *fixes:
> 	spi: Extend the core to ease integration of SPI memory controllers
> ---
>  drivers/spi/spi-mem.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> index 990770d..f5e75d1 100644
> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -328,10 +328,21 @@ EXPORT_SYMBOL_GPL(spi_mem_exec_op);
>  int spi_mem_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
>  {
>  	struct spi_controller *ctlr = mem->spi->controller;
> +	unsigned long val =	sizeof(op->cmd.opcode) +
> +							  op->addr.nbytes +
> +							  op->dummy.nbytes;

Not properly aligned, and you should find a better name for this variable.

>  
>  	if (ctlr->mem_ops && ctlr->mem_ops->adjust_op_size)
>  		return ctlr->mem_ops->adjust_op_size(mem, op);
>  
> +	if (spi_max_message_size(mem->spi) < val)
> +		return -EINVAL;

This should be enclosed in the if (!ctlr->mem_ops || !ctlr->mem_ops->exec_op)
block and you should check that spi_max_transfer_size(mem->spi) >= val too.

> +
> +	if (!ctlr->mem_ops || !ctlr->mem_ops->exec_op)
> +		op->data.nbytes = min3((unsigned long)op->data.nbytes,
> +				spi_max_transfer_size(mem->spi),
> +				spi_max_message_size(mem->spi) - val);
> +
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(spi_mem_adjust_op_size);

Regards,

Boris