Re: [PATCH] netpoll: Fix carrier detection for drivers that are using phylib

Peter Zijlstra
2009-07-09T14:31:11Z

On Thu, 2009-07-09 at 09:18 -0500, Matt Mackall wrote:
>
> Sorry if I was unclear. I'm suggesting setting the count so the existing
> PREEMPT_ACTIVE test here fires:
>
> int __sched _cond_resched(void)
> {
> if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE) &&
> system_state == SYSTEM_RUNNING) {
> __cond_resched();
> return 1;
> }
> return 0;
> }

Right, /me read preempt and thought a simple preempt inc but didn't read
the code. Shame on me.

So something like (utterly untested and such)

---

arch/x86/include/asm/thread_info.h | 2 +-
kernel/sched.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index b078352..7b5dbce 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -49,7 +49,7 @@ struct thread_info {
.exec_domain = &default_exec_domain, \
.flags = 0, \
.cpu = 0, \
- .preempt_count = 1, \
+ .preempt_count = 1 + PREEMPT_ACTIVE, \
.addr_limit = KERNEL_DS, \
.restart_block = { \
.fn = do_no_restart_syscall, \
diff --git a/kernel/sched.c b/kernel/sched.c
index fd3ac58..8e81162 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6599,8 +6599,7 @@ static void __cond_resched(void)

int __sched _cond_resched(void)
{
- if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE) &&
- system_state == SYSTEM_RUNNING) {
+ if (need_resched() && !(preempt_count() & PREEMPT_ACTIVE)) {
__cond_resched();
return 1;
}
@@ -9422,6 +9421,7 @@ void __init sched_init(void)
perf_counter_init();

scheduler_running = 1;
+ sub_preempt_count(PREEMPT_ACTIVE);
}

#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP