locking/rwlocks: introduce write_lock_nested
In preparation for converting bit_spin_lock to rwlock in zsmalloc so
that multiple writers of zspages can run at the same time but those
zspages are supposed to be different zspage instance. Thus, it's not
deadlock. This patch adds write_lock_nested to support the case for
LOCKDEP.
[[email protected]: fix write_lock_nested for RT]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: fixup write_lock_nested() implementation]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Minchan Kim <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Sebastian Andrzej Siewior <[email protected]>
Tested-by: Sebastian Andrzej Siewior <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Naresh Kamboju <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/include/linux/rwlock_api_smp.h b/include/linux/rwlock_api_smp.h
index f1db6f1..dceb0a5 100644
--- a/include/linux/rwlock_api_smp.h
+++ b/include/linux/rwlock_api_smp.h
@@ -17,6 +17,7 @@
void __lockfunc _raw_read_lock(rwlock_t *lock) __acquires(lock);
void __lockfunc _raw_write_lock(rwlock_t *lock) __acquires(lock);
+void __lockfunc _raw_write_lock_nested(rwlock_t *lock, int subclass) __acquires(lock);
void __lockfunc _raw_read_lock_bh(rwlock_t *lock) __acquires(lock);
void __lockfunc _raw_write_lock_bh(rwlock_t *lock) __acquires(lock);
void __lockfunc _raw_read_lock_irq(rwlock_t *lock) __acquires(lock);
@@ -209,6 +210,13 @@ static inline void __raw_write_lock(rwlock_t *lock)
LOCK_CONTENDED(lock, do_raw_write_trylock, do_raw_write_lock);
}
+static inline void __raw_write_lock_nested(rwlock_t *lock, int subclass)
+{
+ preempt_disable();
+ rwlock_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
+ LOCK_CONTENDED(lock, do_raw_write_trylock, do_raw_write_lock);
+}
+
#endif /* !CONFIG_GENERIC_LOCKBREAK || CONFIG_DEBUG_LOCK_ALLOC */
static inline void __raw_write_unlock(rwlock_t *lock)
