2008-10-04 20:06:00

by Julia Lawall

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

From: Julia Lawall <[email protected]>

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 <[email protected]>

---
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;

2008-10-06 01:25:20

by M. Asselstine

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

On Sat, Oct 4, 2008 at 4:05 PM, Julia Lawall <[email protected]> wrote:
> From: Julia Lawall <[email protected]>
>
> 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 <[email protected]>
Reviewed-by: Mark Asselstine <[email protected]>

>
> ---
> 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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>

2008-10-06 10:53:05

by Heiko Carstens

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

On Sat, Oct 04, 2008 at 10:05:47PM +0200, Julia Lawall wrote:
> From: Julia Lawall <[email protected]>
>
> 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!