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/include/linux/spinlock.h b/include/linux/spinlock.h
index c376f3b..1244497 100644
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -120,6 +120,12 @@
#define spin_is_locked(lock) __raw_spin_is_locked(&(lock)->raw_lock)
+#ifdef CONFIG_GENERIC_LOCKBREAK
+#define spin_is_contended(lock) ((lock)->break_lock)
+#else
+#define spin_is_contended(lock) __raw_spin_is_contended(&(lock)->raw_lock)
+#endif
+
/**
* spin_unlock_wait - wait until the spinlock gets unlocked
* @lock: the spinlock in question.