[PATCH 2/2] drivers/s390/cio/chsc_sch.c: Correct use of ! and &

[PATCH 2/2] drivers/s390/cio/chsc_sch.c: Correct use of ! and &

[Julia Lawall]

From: Julia Lawall <julia@diku.dk>

In commit e6bafba5b4765a5a252f1b8d31cbf6d2459da337, a bug was fixed that
involved converting !x & y to !(x & y).  The code below shows the same
pattern, and thus should perhaps be fixed in the same way.  In particular,
the result of !scsw_stctl(&request->irb.scsw) & SCSW_STCTL_STATUS_PEND is
always just !scsw_stctl(&request->irb.scsw).

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@ expression E; constant C; @@
(
  !E & !C
|
- !E & C
+ !(E & C)
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
 drivers/s390/cio/chsc_sch.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -u -p a/drivers/s390/cio/chsc_sch.c b/drivers/s390/cio/chsc_sch.c
--- a/drivers/s390/cio/chsc_sch.c
+++ b/drivers/s390/cio/chsc_sch.c
@@ -261,7 +261,7 @@ static int chsc_examine_irb(struct chsc_
 {
 	int backed_up;
 
-	if (!scsw_stctl(&request->irb.scsw) & SCSW_STCTL_STATUS_PEND)
+	if (!(scsw_stctl(&request->irb.scsw) & SCSW_STCTL_STATUS_PEND))
 		return -EIO;
 	backed_up = scsw_cstat(&request->irb.scsw) & SCHN_STAT_CHAIN_CHECK;
 	request->irb.scsw.cmd.cstat &= ~SCHN_STAT_CHAIN_CHECK;

Re: [PATCH 2/2] drivers/s390/cio/chsc_sch.c: Correct use of ! and &

[M. Asselstine]

On Sat, Oct 4, 2008 at 4:05 PM, Julia Lawall <julia@diku.dk> wrote:
> From: Julia Lawall <julia@diku.dk>
>
> In commit e6bafba5b4765a5a252f1b8d31cbf6d2459da337, a bug was fixed that
> involved converting !x & y to !(x & y).  The code below shows the same
> pattern, and thus should perhaps be fixed in the same way.  In particular,
> the result of !scsw_stctl(&request->irb.scsw) & SCSW_STCTL_STATUS_PEND is
> always just !scsw_stctl(&request->irb.scsw).
>
> The semantic patch that makes this change is as follows:
> (http://www.emn.fr/x-info/coccinelle/)
>
> // <smpl>
> @@ expression E; constant C; @@
> (
>  !E & !C
> |
> - !E & C
> + !(E & C)
> )
> // </smpl>
>
> Signed-off-by: Julia Lawall <julia@diku.dk>
Reviewed-by: Mark Asselstine <mark.asselstine@windriver.com>

>
> ---
>  drivers/s390/cio/chsc_sch.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff -u -p a/drivers/s390/cio/chsc_sch.c b/drivers/s390/cio/chsc_sch.c
> --- a/drivers/s390/cio/chsc_sch.c
> +++ b/drivers/s390/cio/chsc_sch.c
> @@ -261,7 +261,7 @@ static int chsc_examine_irb(struct chsc_
>  {
>        int backed_up;
>
> -       if (!scsw_stctl(&request->irb.scsw) & SCSW_STCTL_STATUS_PEND)
> +       if (!(scsw_stctl(&request->irb.scsw) & SCSW_STCTL_STATUS_PEND))
>                return -EIO;
>        backed_up = scsw_cstat(&request->irb.scsw) & SCHN_STAT_CHAIN_CHECK;
>        request->irb.scsw.cmd.cstat &= ~SCHN_STAT_CHAIN_CHECK;
> --
> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
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>

Re: [PATCH 2/2] drivers/s390/cio/chsc_sch.c: Correct use of ! and &

[Heiko Carstens]

On Sat, Oct 04, 2008 at 10:05:47PM +0200, Julia Lawall wrote:
> From: Julia Lawall <julia@diku.dk>
> 
> In commit e6bafba5b4765a5a252f1b8d31cbf6d2459da337, a bug was fixed that
> involved converting !x & y to !(x & y).  The code below shows the same
> pattern, and thus should perhaps be fixed in the same way.  In particular,
> the result of !scsw_stctl(&request->irb.scsw) & SCSW_STCTL_STATUS_PEND is
> always just !scsw_stctl(&request->irb.scsw).
> [...]
> -	if (!scsw_stctl(&request->irb.scsw) & SCSW_STCTL_STATUS_PEND)
> +	if (!(scsw_stctl(&request->irb.scsw) & SCSW_STCTL_STATUS_PEND))
>  		return -EIO;
>  	backed_up = scsw_cstat(&request->irb.scsw) & SCHN_STAT_CHAIN_CHECK;
>  	request->irb.scsw.cmd.cstat &= ~SCHN_STAT_CHAIN_CHECK;

Nice finding. Thank you!