Re: [PATCH] sg.c to set direction more reliably (was Re: [PATCH] fusion update to current APIs)

[Patrick Mansfield <patmans@us.ibm.com>]

On Tue, Jun 15, 2004 at 02:31:48AM -0700, Jeremy Higdon wrote:
> On Tue, Jun 15, 2004 at 02:10:43AM -0700, Jeremy Higdon wrote:
> > One more comment from hch via IRC.  When we have to guess direction,
> > print a suggestion to use SG v3 interface.

But print only once, so borked applications that continually poll devices
won't generate lots of these messages.

> +	/*
> +	 * If data direction is indeterminate because both input and output size
> +	 * are greater than 0, use command bytes to determine direction.
> +	 */
> +	if (input_size == 0 && mxsize > 0)
> +		hp->dxfer_direction = SG_DXFER_FROM_DEV;
> +	else if (input_size > 0 && old_hdr.reply_len <= SZ_SG_HEADER)
> +		hp->dxfer_direction = SG_DXFER_TO_DEV;
> +	else if (input_size == 0 && mxsize == 0)
> +		hp->dxfer_direction = SG_DXFER_NONE;
> +	else {
> +		hp->dxfer_direction = sg_direction(cmnd);
> +		printk("sg_write: cannot infer direction from count %ld "
> +		       "and reply_len %d; inferring from command 0x%x.  Please "
> +		       "fix the application to use the sg version 3 interface\n",
> +		       count, old_hdr.reply_len, (unsigned int) cmnd[0]);
> +	}
>  	k = sg_common_write(sfp, srp, cmnd, sfp->timeout, blocking);
>  	return (k < 0) ? k : count;
>  }