[patch 3/8] kernel/sched.c: fix subtle TASK_RUNNING compare

[patch 3/8] kernel/sched.c: fix subtle TASK_RUNNING compare

[janitor]

Hi.

This test was depending on TASK_RUNNING being defined as 0.

Signed-off-by: Domen Puncer <domen@coderock.org>

Signed-off-by: Maximilian Attems <janitor@sternwelten.at>
---

 linux-2.6.10-rc2-bk4-max/kernel/sched.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletion(-)

diff -puN kernel/sched.c~fix-test-kernel_sched kernel/sched.c
--- linux-2.6.10-rc2-bk4/kernel/sched.c~fix-test-kernel_sched	2004-11-20 03:04:46.000000000 +0100
+++ linux-2.6.10-rc2-bk4-max/kernel/sched.c	2004-11-20 03:04:46.000000000 +0100
@@ -2576,7 +2576,8 @@ need_resched_nonpreemptible:
 	 * to picking the next task.
 	 */
 	switch_count = &prev->nivcsw;
-	if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
+	if (prev->state != TASK_RUNNING &&
+			!(preempt_count() & PREEMPT_ACTIVE)) {
 		switch_count = &prev->nvcsw;
 		if (unlikely((prev->state & TASK_INTERRUPTIBLE) &&
 				unlikely(signal_pending(prev))))
_

Re: kernel/sched.c: fix subtle TASK_RUNNING compare

[Domen Puncer]

On 20/11/04 13:53 +0100, Ingo Molnar wrote:
> 
> * janitor@sternwelten.at <janitor@sternwelten.at> wrote:
> 
> >  	switch_count = &prev->nivcsw;
> > -	if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
> > +	if (prev->state != TASK_RUNNING &&
> > +			!(preempt_count() & PREEMPT_ACTIVE)) {
> >  		switch_count = &prev->nvcsw;
> 
> nack. We inherently rely on the process state mask being a bitmask and
> TASK_RUNNING thus being zero.

Hmm... but other compares in sched.c are ok? ;-)
1211:   BUG_ON(p->state != TASK_RUNNING);
2550:   if (unlikely(current == rq->idle) && current->state != TASK_RUNNING) {
3609:   if (state == TASK_RUNNING)
3640:   if (state != TASK_RUNNING)

Well, it just looks more readable to me. But i don't have too strong
feelings about this. :-)


	Domen

Re: [patch 3/8] kernel/sched.c: fix subtle TASK_RUNNING compare

[Ingo Molnar]

* janitor@sternwelten.at <janitor@sternwelten.at> wrote:

>  	switch_count = &prev->nivcsw;
> -	if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
> +	if (prev->state != TASK_RUNNING &&
> +			!(preempt_count() & PREEMPT_ACTIVE)) {
>  		switch_count = &prev->nvcsw;

nack. We inherently rely on the process state mask being a bitmask and
TASK_RUNNING thus being zero.

	Ingo

Re: kernel/sched.c: fix subtle TASK_RUNNING compare

[Ingo Molnar]

* Domen Puncer <domen@coderock.org> wrote:

> On 20/11/04 13:53 +0100, Ingo Molnar wrote:
> > 
> > * janitor@sternwelten.at <janitor@sternwelten.at> wrote:
> > 
> > >  	switch_count = &prev->nivcsw;
> > > -	if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
> > > +	if (prev->state != TASK_RUNNING &&
> > > +			!(preempt_count() & PREEMPT_ACTIVE)) {
> > >  		switch_count = &prev->nvcsw;
> > 
> > nack. We inherently rely on the process state mask being a bitmask and
> > TASK_RUNNING thus being zero.
> 
> Hmm... but other compares in sched.c are ok? ;-)
> 1211:   BUG_ON(p->state != TASK_RUNNING);
> 2550:   if (unlikely(current == rq->idle) && current->state != TASK_RUNNING) {
> 3609:   if (state == TASK_RUNNING)
> 3640:   if (state != TASK_RUNNING)

hm ... ok.

	Ingo