linux-kernel - Re: [PATCH] USB: misplaced parenthesis

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Date:	Tue, 16 Feb 2010 12:16:22 +0100
From:	Roel Kluin <roel.kluin@...il.com>
To:	Joe Perches <joe@...ches.com>
CC:	Matthew Dharm <mdharm-usb@...-eyed-alien.net>,
	linux-usb@...r.kernel.org, usb-storage@...ts.one-eyed-alien.net,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] USB: misplaced parenthesis

> I think it'd be better if you hoisted the set'n'test out of the if()

ok, I agree.

> Isn't this the current logic?
> 
> 	result = usbat_write_block(us, USBAT_ATA, srb->cmnd, 12,
> 				   srb->cmnd[0] == GPCMD_BLANK ? 75 : 10, 0);
> 	result = result != USB_STOR_TRANSPORT_GOOD;
> 	if (result)
> 		return result;

Thanks for your comments, Yes that was the current logic, which I thought
was wrong, but now I think it could also be obscurely written but right:

in drivers/usb/storage/transport.h line 100 note the definitions:

#define USB_STOR_TRANSPORT_GOOD    0   /* Transport good, command good     */
#define USB_STOR_TRANSPORT_FAILED  1   /* Transport good, command failed   */
#define USB_STOR_TRANSPORT_NO_SENSE 2  /* Command failed, no auto-sense    */
#define USB_STOR_TRANSPORT_ERROR   3   /* Transport bad (i.e. device dead) */

With the current logic usbat_hp8200e_transport() returns TRANSPORT_FAILED,
even if usbat_write_block() returned TRANSPORT_NO_SENSE or TRANSPORT_ERROR.

This could be intended, but then the author chose a very obscure way to write:

	if (usbat_write_block(us, USBAT_ATA, srb->cmnd, 12,
			      srb->cmnd[0] == GPCMD_BLANK ? 75 : 10, 0) !=
			      USB_STOR_TRANSPORT_GOOD) 
		return USB_STOR_TRANSPORT_FAILED;

Or was the parenthesis misplaced and should it really be:

	result = usbat_write_block(us, USBAT_ATA, srb->cmnd, 12,
				   srb->cmnd[0] == GPCMD_BLANK ? 75 : 10, 0);

	if (result != USB_STOR_TRANSPORT_GOOD)
 		return result;
 
Maybe someone with the specs/more knowledge of this driver could look into
this?

Thanks, Roel
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