[PATCH v2] sched/deadline: Use unsigned type for the state flags

From: Jiri Kosina
Date: Tue Nov 21 2017 - 07:01:06 EST


799ba82de01e ("sched/deadline: Use C bitfields for the state flags")

converted state flags into one-bit signed int. Signed one-bit type can be
either 0 or -1, which is going to cause a problem once 1 is assigned to
it and then the value later tested against 1.

The current code is okay, as all the checks are (non-)zero check, but I believe
that we'd rather be safe than sorry here; remove the fragility by converting
the state flags to unsigned int, where 1 actually really is 1.

This also silences annoying sparse complaints about this very issue when
compiling any code that includes sched.h.

Fixes: 799ba82de01e ("sched/deadline: Use C bitfields for the state flags")
Cc: luca abeni <luca.abeni@xxxxxxxxxxxxxxx>
Cc: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>

v2: switch over to unsisgned int from bool, as asked for by Thomas. Feel
free to pick either of the versions

include/linux/sched.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index a5dc7c98b0a2..b634da8a35a3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -473,10 +473,10 @@ struct sched_dl_entity {
* conditions between the inactive timer handler and the wakeup
* code.
- int dl_throttled : 1;
- int dl_boosted : 1;
- int dl_yielded : 1;
- int dl_non_contending : 1;
+ unsigned int dl_throttled : 1;
+ unsigned int dl_boosted : 1;
+ unsigned int dl_yielded : 1;
+ unsigned int dl_non_contending : 1;

* Bandwidth enforcement timer. Each -deadline task has its
Jiri Kosina