locking/rwlock, spinlock: Support Clang's context analysis

Add support for Clang's context analysis for raw_spinlock_t,
spinlock_t, and rwlock. This wholesale conversion is required because
all three of them are interdependent.

To avoid warnings in constructors, the initialization functions mark a
lock as acquired when initialized before guarded variables.

The test verifies that common patterns do not generate false positives.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251219154418.3592607-9-elver@google.com

1 files changed, 23 insertions, 6 deletions

diff --git a/include/linux/rwlock_api_smp.h b/include/linux/rwlock_api_smp.h
index 31d3d1116323..6d5cc0b7be1f 100644
--- a/include/linux/rwlock_api_smp.h
+++ b/include/linux/rwlock_api_smp.h
@@ -15,12 +15,12 @@
  * Released under the General Public License (GPL).
  */
 
-void __lockfunc _raw_read_lock(rwlock_t *lock)		__acquires(lock);
+void __lockfunc _raw_read_lock(rwlock_t *lock)		__acquires_shared(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_read_lock_bh(rwlock_t *lock)	__acquires_shared(lock);
 void __lockfunc _raw_write_lock_bh(rwlock_t *lock)	__acquires(lock);
-void __lockfunc _raw_read_lock_irq(rwlock_t *lock)	__acquires(lock);
+void __lockfunc _raw_read_lock_irq(rwlock_t *lock)	__acquires_shared(lock);
 void __lockfunc _raw_write_lock_irq(rwlock_t *lock)	__acquires(lock);
 unsigned long __lockfunc _raw_read_lock_irqsave(rwlock_t *lock)
 							__acquires(lock);
@@ -28,11 +28,11 @@ unsigned long __lockfunc _raw_write_lock_irqsave(rwlock_t *lock)
 							__acquires(lock);
 int __lockfunc _raw_read_trylock(rwlock_t *lock);
 int __lockfunc _raw_write_trylock(rwlock_t *lock);
-void __lockfunc _raw_read_unlock(rwlock_t *lock)	__releases(lock);
+void __lockfunc _raw_read_unlock(rwlock_t *lock)	__releases_shared(lock);
 void __lockfunc _raw_write_unlock(rwlock_t *lock)	__releases(lock);
-void __lockfunc _raw_read_unlock_bh(rwlock_t *lock)	__releases(lock);
+void __lockfunc _raw_read_unlock_bh(rwlock_t *lock)	__releases_shared(lock);
 void __lockfunc _raw_write_unlock_bh(rwlock_t *lock)	__releases(lock);
-void __lockfunc _raw_read_unlock_irq(rwlock_t *lock)	__releases(lock);
+void __lockfunc _raw_read_unlock_irq(rwlock_t *lock)	__releases_shared(lock);
 void __lockfunc _raw_write_unlock_irq(rwlock_t *lock)	__releases(lock);
 void __lockfunc
 _raw_read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
@@ -145,6 +145,7 @@ static inline int __raw_write_trylock(rwlock_t *lock)
 #if !defined(CONFIG_GENERIC_LOCKBREAK) || defined(CONFIG_DEBUG_LOCK_ALLOC)
 
 static inline void __raw_read_lock(rwlock_t *lock)
+	__acquires_shared(lock) __no_context_analysis
 {
 	preempt_disable();
 	rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
@@ -152,6 +153,7 @@ static inline void __raw_read_lock(rwlock_t *lock)
 }
 
 static inline unsigned long __raw_read_lock_irqsave(rwlock_t *lock)
+	__acquires_shared(lock) __no_context_analysis
 {
 	unsigned long flags;
 
@@ -163,6 +165,7 @@ static inline unsigned long __raw_read_lock_irqsave(rwlock_t *lock)
 }
 
 static inline void __raw_read_lock_irq(rwlock_t *lock)
+	__acquires_shared(lock) __no_context_analysis
 {
 	local_irq_disable();
 	preempt_disable();
@@ -171,6 +174,7 @@ static inline void __raw_read_lock_irq(rwlock_t *lock)
 }
 
 static inline void __raw_read_lock_bh(rwlock_t *lock)
+	__acquires_shared(lock) __no_context_analysis
 {
 	__local_bh_disable_ip(_RET_IP_, SOFTIRQ_LOCK_OFFSET);
 	rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
@@ -178,6 +182,7 @@ static inline void __raw_read_lock_bh(rwlock_t *lock)
 }
 
 static inline unsigned long __raw_write_lock_irqsave(rwlock_t *lock)
+	__acquires(lock) __no_context_analysis
 {
 	unsigned long flags;
 
@@ -189,6 +194,7 @@ static inline unsigned long __raw_write_lock_irqsave(rwlock_t *lock)
 }
 
 static inline void __raw_write_lock_irq(rwlock_t *lock)
+	__acquires(lock) __no_context_analysis
 {
 	local_irq_disable();
 	preempt_disable();
@@ -197,6 +203,7 @@ static inline void __raw_write_lock_irq(rwlock_t *lock)
 }
 
 static inline void __raw_write_lock_bh(rwlock_t *lock)
+	__acquires(lock) __no_context_analysis
 {
 	__local_bh_disable_ip(_RET_IP_, SOFTIRQ_LOCK_OFFSET);
 	rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
@@ -204,6 +211,7 @@ static inline void __raw_write_lock_bh(rwlock_t *lock)
 }
 
 static inline void __raw_write_lock(rwlock_t *lock)
+	__acquires(lock) __no_context_analysis
 {
 	preempt_disable();
 	rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
@@ -211,6 +219,7 @@ static inline void __raw_write_lock(rwlock_t *lock)
 }
 
 static inline void __raw_write_lock_nested(rwlock_t *lock, int subclass)
+	__acquires(lock) __no_context_analysis
 {
 	preempt_disable();
 	rwlock_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
@@ -220,6 +229,7 @@ static inline void __raw_write_lock_nested(rwlock_t *lock, int subclass)
 #endif /* !CONFIG_GENERIC_LOCKBREAK || CONFIG_DEBUG_LOCK_ALLOC */
 
 static inline void __raw_write_unlock(rwlock_t *lock)
+	__releases(lock)
 {
 	rwlock_release(&lock->dep_map, _RET_IP_);
 	do_raw_write_unlock(lock);
@@ -227,6 +237,7 @@ static inline void __raw_write_unlock(rwlock_t *lock)
 }
 
 static inline void __raw_read_unlock(rwlock_t *lock)
+	__releases_shared(lock)
 {
 	rwlock_release(&lock->dep_map, _RET_IP_);
 	do_raw_read_unlock(lock);
@@ -235,6 +246,7 @@ static inline void __raw_read_unlock(rwlock_t *lock)
 
 static inline void
 __raw_read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
+	__releases_shared(lock)
 {
 	rwlock_release(&lock->dep_map, _RET_IP_);
 	do_raw_read_unlock(lock);
@@ -243,6 +255,7 @@ __raw_read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 }
 
 static inline void __raw_read_unlock_irq(rwlock_t *lock)
+	__releases_shared(lock)
 {
 	rwlock_release(&lock->dep_map, _RET_IP_);
 	do_raw_read_unlock(lock);
@@ -251,6 +264,7 @@ static inline void __raw_read_unlock_irq(rwlock_t *lock)
 }
 
 static inline void __raw_read_unlock_bh(rwlock_t *lock)
+	__releases_shared(lock)
 {
 	rwlock_release(&lock->dep_map, _RET_IP_);
 	do_raw_read_unlock(lock);
@@ -259,6 +273,7 @@ static inline void __raw_read_unlock_bh(rwlock_t *lock)
 
 static inline void __raw_write_unlock_irqrestore(rwlock_t *lock,
 					     unsigned long flags)
+	__releases(lock)
 {
 	rwlock_release(&lock->dep_map, _RET_IP_);
 	do_raw_write_unlock(lock);
@@ -267,6 +282,7 @@ static inline void __raw_write_unlock_irqrestore(rwlock_t *lock,
 }
 
 static inline void __raw_write_unlock_irq(rwlock_t *lock)
+	__releases(lock)
 {
 	rwlock_release(&lock->dep_map, _RET_IP_);
 	do_raw_write_unlock(lock);
@@ -275,6 +291,7 @@ static inline void __raw_write_unlock_irq(rwlock_t *lock)
 }
 
 static inline void __raw_write_unlock_bh(rwlock_t *lock)
+	__releases(lock)
 {
 	rwlock_release(&lock->dep_map, _RET_IP_);
 	do_raw_write_unlock(lock);