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

[Douglas Gilbert <dougg@torque.net>]

Jeremy Higdon wrote:
> I still think that this change should go into the sg1/sg2 command
> issue path, so that a warning is issued when sg has to guess on
> command direction.  This will encourage developers to fix up apps
> that don't set buffer sizes properly.
> 
> Doug, can you comment on this?  If you don't like it, I'll drop
> it  :-)
> 
> This patch is against 2.6.9-rc1.
> 
> thanks,
> 
> jeremy
> 
> ===== drivers/scsi/sg.c 1.95 vs edited =====
> --- 1.95/drivers/scsi/sg.c	2004-08-07 19:11:33 -07:00
> +++ edited/drivers/scsi/sg.c	2004-08-26 00:04:25 -07:00
> @@ -564,6 +564,17 @@
>  	hp->usr_ptr = NULL;
>  	if (__copy_from_user(cmnd, buf, cmd_size))
>  		return -EFAULT;
> +	/*
> +	 * SG_DXFER_TO_FROM_DEV is functionally equivalent to SG_DXFER_FROM_DEV,
> +	 * but is is possible that the app intended SG_DXFER_TO_DEV, because there
> +	 * is a non-zero input_size, so emit a warning.
> +	 */
> +	if (hp->dxfer_direction == SG_DXFER_TO_FROM_DEV)
> +		printk("sg_write: cannot infer direction from count %ld "
> +		       "and reply_len %d.  Command 0x%x will probably fail. "
> +		       "Please fix the application to use proper counts or "
> +		       "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;
>  }
> 
Jeremy,
Perhaps the first argument of printk() could be prefixed with
KERN_WARNING to make it a bit more syslog friendly.
Otherwise ok.

Doug Gilbert