spinlock: lockbreak cleanup
The break_lock data structure and code for spinlocks is quite nasty.
Not only does it double the size of a spinlock but it changes locking to
a potentially less optimal trylock.
Put all of that under CONFIG_GENERIC_LOCKBREAK, and introduce a
__raw_spin_is_contended that uses the lock data itself to determine whether
there are waiters on the lock, to be used if CONFIG_GENERIC_LOCKBREAK is
not set.
Rename need_lockbreak to spin_needbreak, make it use spin_is_contended to
decouple it from the spinlock implementation, and make it typesafe (rwlocks
do not have any need_lockbreak sites -- why do they even get bloated up
with that break_lock then?).
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/sched.c b/kernel/sched.c
index 524285e..ba4c880 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4945,19 +4945,15 @@
*/
int cond_resched_lock(spinlock_t *lock)
{
+ int resched = need_resched() && system_state == SYSTEM_RUNNING;
int ret = 0;
- if (need_lockbreak(lock)) {
+ if (spin_needbreak(lock) || resched) {
spin_unlock(lock);
- cpu_relax();
- ret = 1;
- spin_lock(lock);
- }
- if (need_resched() && system_state == SYSTEM_RUNNING) {
- spin_release(&lock->dep_map, 1, _THIS_IP_);
- _raw_spin_unlock(lock);
- preempt_enable_no_resched();
- __cond_resched();
+ if (resched && need_resched())
+ __cond_resched();
+ else
+ cpu_relax();
ret = 1;
spin_lock(lock);
}