[PATCH] USB: misplaced parenthesis

[PATCH] USB: misplaced parenthesis

[Roel Kluin]

The parenthesis was misplaced

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
---
Is this maybe, as the comment states, why blanking a cdrw at speed 4
was unreliable?

diff --git a/drivers/usb/storage/shuttle_usbat.c b/drivers/usb/storage/shuttle_usbat.c
index b62a288..b958db5 100644
--- a/drivers/usb/storage/shuttle_usbat.c
+++ b/drivers/usb/storage/shuttle_usbat.c
@@ -1645,8 +1645,8 @@ static int usbat_hp8200e_transport(struct scsi_cmnd *srb, struct us_data *us)
 
 	if ((result = usbat_write_block(us,
 			USBAT_ATA, srb->cmnd, 12,
-				(srb->cmnd[0]==GPCMD_BLANK ? 75 : 10), 0) !=
-			     USB_STOR_TRANSPORT_GOOD)) {
+				(srb->cmnd[0]==GPCMD_BLANK ? 75 : 10), 0)) !=
+			     USB_STOR_TRANSPORT_GOOD) {
 		return result;
 	}
 

Re: [PATCH] USB: misplaced parenthesis

[Joe Perches]

On Mon, 2010-02-15 at 23:40 +0100, Roel Kluin wrote:
> The parenthesis was misplaced
> 
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
> ---
> Is this maybe, as the comment states, why blanking a cdrw at speed 4
> was unreliable?
> 
> diff --git a/drivers/usb/storage/shuttle_usbat.c b/drivers/usb/storage/shuttle_usbat.c
> index b62a288..b958db5 100644
> --- a/drivers/usb/storage/shuttle_usbat.c
> +++ b/drivers/usb/storage/shuttle_usbat.c
> @@ -1645,8 +1645,8 @@ static int usbat_hp8200e_transport(struct scsi_cmnd *srb, struct us_data *us)
>  
>  	if ((result = usbat_write_block(us,
>  			USBAT_ATA, srb->cmnd, 12,
> -				(srb->cmnd[0]==GPCMD_BLANK ? 75 : 10), 0) !=
> -			     USB_STOR_TRANSPORT_GOOD)) {
> +				(srb->cmnd[0]==GPCMD_BLANK ? 75 : 10), 0)) !=
> +			     USB_STOR_TRANSPORT_GOOD) {
>  		return result;
>  	}

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

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;

I wonder if it should 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;

Re: [PATCH] USB: misplaced parenthesis

[Roel Kluin]

> 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

Re: [PATCH] USB: misplaced parenthesis

[Alan Stern]

On Tue, 16 Feb 2010, Roel Kluin wrote:

> > 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?

It seems pretty clear that your patch was correct and the parens were 
misplaced.  In usb-storage, transport routines like 
usbat_hp8200e_transport() are supposed to return one of the 
USB_STOR_TRANSPORT_* codes, not a Boolean value.

I do agree with Joe that it would be better form to separate the 
function call and the "if" into two statements, as in your second 
version above.  Compare with the code a few lines higher:

        if ( (result = usbat_multiple_write(us, 
                        registers, data, 7)) != USB_STOR_TRANSPORT_GOOD) {
                return result;
        }

The meaning is clear, even though this also unnecessarily squeezes a 
function call and a test into one statement and includes unneeded {}'s.

Alan Stern

Re: [PATCH] USB: misplaced parenthesis

[Roel Kluin]

Due to a misplaced parenthesis the usbat_write_block() return value was not
stored, but a boolean. USB_STOR_TRANSPORT_NO_SENSE and USB_STOR_TRANSPORT_ERROR
were returned as USB_STOR_TRANSPORT_FAILED.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
---
>> 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) */

> It seems pretty clear that your patch was correct and the parens were 
> misplaced.  In usb-storage, transport routines like 
> usbat_hp8200e_transport() are supposed to return one of the 
> USB_STOR_TRANSPORT_* codes, not a Boolean value.
> 
> I do agree with Joe that it would be better form to separate the 
> function call and the "if" into two statements, as in your second 
> version above.

Ok, thanks for comments, This should fix and separate the assignment as desired.

Roel

diff --git a/drivers/usb/storage/shuttle_usbat.c b/drivers/usb/storage/shuttle_usbat.c
index b62a288..bd3f415 100644
--- a/drivers/usb/storage/shuttle_usbat.c
+++ b/drivers/usb/storage/shuttle_usbat.c
@@ -1628,10 +1628,10 @@ static int usbat_hp8200e_transport(struct scsi_cmnd *srb, struct us_data *us)
 		return USB_STOR_TRANSPORT_ERROR;
 	}
 
-	if ( (result = usbat_multiple_write(us, 
-			registers, data, 7)) != USB_STOR_TRANSPORT_GOOD) {
+	result = usbat_multiple_write(us, registers, data, 7);
+
+	if (result != USB_STOR_TRANSPORT_GOOD)
 		return result;
-	}
 
 	/*
 	 * Write the 12-byte command header.
@@ -1643,12 +1643,11 @@ static int usbat_hp8200e_transport(struct scsi_cmnd *srb, struct us_data *us)
 	 * AT SPEED 4 IS UNRELIABLE!!!
 	 */
 
-	if ((result = usbat_write_block(us,
-			USBAT_ATA, srb->cmnd, 12,
-				(srb->cmnd[0]==GPCMD_BLANK ? 75 : 10), 0) !=
-			     USB_STOR_TRANSPORT_GOOD)) {
+	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;
-	}
 
 	/* If there is response data to be read in then do it here. */