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SubjectRe: mmotm 2013-06-27-16-36 uploaded (wait event common)
Hi Guys,

On Thu, 27 Jun 2013 23:06:43 -0700 Randy Dunlap <rdunlap@infradead.org> wrote:
>
> On 06/27/13 22:51, Andrew Morton wrote:
> > On Thu, 27 Jun 2013 22:30:41 -0700 Randy Dunlap <rdunlap@infradead.org> wrote:
> >
> >> On 06/27/13 16:37, akpm@linux-foundation.org wrote:
> >>> The mm-of-the-moment snapshot 2013-06-27-16-36 has been uploaded to
> >>>
> >>> http://www.ozlabs.org/~akpm/mmotm/
> >>>
> >>> mmotm-readme.txt says
> >>>
> >>> README for mm-of-the-moment:
> >>>
> >>> http://www.ozlabs.org/~akpm/mmotm/
> >>>
> >>
> >> My builds are littered with hundreds of warnings like this one:
> >>
> >> drivers/tty/tty_ioctl.c:220:6: warning: the omitted middle operand in ?: will always be 'true', suggest explicit middle operand [-Wparentheses]
> >>
> >> I guess due to this line from wait_event_common():
> >>
> >> + __ret = __wait_no_timeout(tout) ?: (tout) ?: 1;
> >>
> >
> > Ah, sorry, I missed that. Had I noticed it, I would have spat it back
> > on taste grounds alone, it being unfit for human consumption.
> >
> > Something like this?
> >
> > --- a/include/linux/wait.h~wait-introduce-wait_event_commonwq-condition-state-timeout-fix
> > +++ a/include/linux/wait.h
> > @@ -196,7 +196,11 @@ wait_queue_head_t *bit_waitqueue(void *,
> > for (;;) { \
> > prepare_to_wait(&wq, &__wait, state); \
> > if (condition) { \
> > - __ret = __wait_no_timeout(tout) ?: __tout ?: 1; \
> > + __ret = __wait_no_timeout(tout); \
> > + if (!__ret) \
> > + __ret = __tout; \
> > + if (!__ret) \
> > + __ret = 1; \
> > break; \
> > } \
> > \
> >
> >
>
> That does reduce the number of warnings, but the wait_event_common() macro
> needs similar treatment. I.e., I am still getting those warnings, just not
> quite as many. (down from 2 per source code line to 1 per source code line
> which contains some kind of wait...)

I added the following to linux-next today:
(sorry Randy, I forgot the Reported-by:, Andrew please add)

From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Fri, 28 Jun 2013 16:52:58 +1000
Subject: [PATCH] fix warnings from ?: operator in wait.h

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
include/linux/wait.h | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/include/linux/wait.h b/include/linux/wait.h
index 1c08a6c..f3b793d 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -197,7 +197,12 @@ wait_queue_head_t *bit_waitqueue(void *, int);
for (;;) { \
__ret = prepare_to_wait_event(&wq, &__wait, state); \
if (condition) { \
- __ret = __wait_no_timeout(tout) ?: __tout ?: 1; \
+ __ret = __wait_no_timeout(tout); \
+ if (!__ret) { \
+ __ret = __tout; \
+ if (!__ret) \
+ __ret = 1; \
+ } \
break; \
} \
\
@@ -218,9 +223,14 @@ wait_queue_head_t *bit_waitqueue(void *, int);
#define wait_event_common(wq, condition, state, tout) \
({ \
long __ret; \
- if (condition) \
- __ret = __wait_no_timeout(tout) ?: (tout) ?: 1; \
- else \
+ if (condition) { \
+ __ret = __wait_no_timeout(tout); \
+ if (!__ret) { \
+ __ret = (tout); \
+ if (!__ret) \
+ __ret = 1; \
+ } \
+ } else \
__ret = __wait_event_common(wq, condition, state, tout);\
__ret; \
})
--
1.8.3.1
--
Cheers,
Stephen Rothwell sfr@canb.auug.org.au
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