From 4a57d6bbaecd28c8175dc5da013009e4158018c2 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Fri, 21 Jan 2022 22:14:10 -0800 Subject: 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. [minchan@kernel.org: fix write_lock_nested for RT] Link: https://lkml.kernel.org/r/YZfrMTAXV56HFWJY@google.com [bigeasy@linutronix.de: fixup write_lock_nested() implementation] Link: https://lkml.kernel.org/r/20211123170134.y6xb7pmpgdn4m3bn@linutronix.de Link: https://lkml.kernel.org/r/20211115185909.3949505-8-minchan@kernel.org Signed-off-by: Minchan Kim Signed-off-by: Sebastian Andrzej Siewior Acked-by: Peter Zijlstra (Intel) Acked-by: Sebastian Andrzej Siewior Tested-by: Sebastian Andrzej Siewior Cc: Mike Galbraith Cc: Sergey Senozhatsky Cc: Thomas Gleixner Cc: Naresh Kamboju Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/rwlock_rt.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include/linux/rwlock_rt.h') diff --git a/include/linux/rwlock_rt.h b/include/linux/rwlock_rt.h index 49c1f3842ed5..8544ff05e594 100644 --- a/include/linux/rwlock_rt.h +++ b/include/linux/rwlock_rt.h @@ -28,6 +28,7 @@ extern void rt_read_lock(rwlock_t *rwlock); extern int rt_read_trylock(rwlock_t *rwlock); extern void rt_read_unlock(rwlock_t *rwlock); extern void rt_write_lock(rwlock_t *rwlock); +extern void rt_write_lock_nested(rwlock_t *rwlock, int subclass); extern int rt_write_trylock(rwlock_t *rwlock); extern void rt_write_unlock(rwlock_t *rwlock); @@ -83,6 +84,15 @@ static __always_inline void write_lock(rwlock_t *rwlock) rt_write_lock(rwlock); } +#ifdef CONFIG_DEBUG_LOCK_ALLOC +static __always_inline void write_lock_nested(rwlock_t *rwlock, int subclass) +{ + rt_write_lock_nested(rwlock, subclass); +} +#else +#define write_lock_nested(lock, subclass) rt_write_lock(((void)(subclass), (lock))) +#endif + static __always_inline void write_lock_bh(rwlock_t *rwlock) { local_bh_disable(); -- cgit v1.2.3