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 <minchan@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/rwlock.h b/include/linux/rwlock.h
index 2c0ad41..8f416c5 100644 (file)
--- a/include/linux/rwlock.h
+++ b/include/linux/rwlock.h
@@ -55,6 +55,12 @@ do {                                                         \
 #define write_lock(lock)       _raw_write_lock(lock)
 #define read_lock(lock)                _raw_read_lock(lock)
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#define write_lock_nested(lock, subclass)      _raw_write_lock_nested(lock, subclass)
+#else
+#define write_lock_nested(lock, subclass)      _raw_write_lock(lock)
+#endif
+
 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
 
 #define read_lock_irqsave(lock, flags)                 \

diff --git a/include/linux/rwlock_api_smp.h b/include/linux/rwlock_api_smp.h
index f1db6f1..dceb0a5 100644 (file)
--- 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)

diff --git a/include/linux/rwlock_rt.h b/include/linux/rwlock_rt.h
index 49c1f38..8544ff0 100644 (file)
--- 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();

diff --git a/include/linux/spinlock_api_up.h b/include/linux/spinlock_api_up.h
index d0d1888..b8ba00c 100644 (file)
--- a/include/linux/spinlock_api_up.h
+++ b/include/linux/spinlock_api_up.h
@@ -59,6 +59,7 @@
 #define _raw_spin_lock_nested(lock, subclass)  __LOCK(lock)
 #define _raw_read_lock(lock)                   __LOCK(lock)
 #define _raw_write_lock(lock)                  __LOCK(lock)
+#define _raw_write_lock_nested(lock, subclass) __LOCK(lock)
 #define _raw_spin_lock_bh(lock)                        __LOCK_BH(lock)
 #define _raw_read_lock_bh(lock)                        __LOCK_BH(lock)
 #define _raw_write_lock_bh(lock)               __LOCK_BH(lock)

diff --git a/kernel/locking/spinlock.c b/kernel/locking/spinlock.c
index b562f92..7f49baa 100644 (file)
--- a/kernel/locking/spinlock.c
+++ b/kernel/locking/spinlock.c
@@ -300,6 +300,16 @@ void __lockfunc _raw_write_lock(rwlock_t *lock)
        __raw_write_lock(lock);
 }
 EXPORT_SYMBOL(_raw_write_lock);
+
+#ifndef CONFIG_DEBUG_LOCK_ALLOC
+#define __raw_write_lock_nested(lock, subclass)        __raw_write_lock(((void)(subclass), (lock)))
+#endif
+
+void __lockfunc _raw_write_lock_nested(rwlock_t *lock, int subclass)
+{
+       __raw_write_lock_nested(lock, subclass);
+}
+EXPORT_SYMBOL(_raw_write_lock_nested);
 #endif
 
 #ifndef CONFIG_INLINE_WRITE_LOCK_IRQSAVE

diff --git a/kernel/locking/spinlock_rt.c b/kernel/locking/spinlock_rt.c
index 9e396a0..48a19ed 100644 (file)
--- a/kernel/locking/spinlock_rt.c
+++ b/kernel/locking/spinlock_rt.c
@@ -239,6 +239,18 @@ void __sched rt_write_lock(rwlock_t *rwlock)
 }
 EXPORT_SYMBOL(rt_write_lock);
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+void __sched rt_write_lock_nested(rwlock_t *rwlock, int subclass)
+{
+       rtlock_might_resched();
+       rwlock_acquire(&rwlock->dep_map, subclass, 0, _RET_IP_);
+       rwbase_write_lock(&rwlock->rwbase, TASK_RTLOCK_WAIT);
+       rcu_read_lock();
+       migrate_disable();
+}
+EXPORT_SYMBOL(rt_write_lock_nested);
+#endif
+
 void __sched rt_read_unlock(rwlock_t *rwlock)
 {
        rwlock_release(&rwlock->dep_map, _RET_IP_);