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, 40 insertions, 31 deletions

diff --git a/include/linux/spinlock_api_up.h b/include/linux/spinlock_api_up.h
index 819aeba1c87e..018f5aabc1be 100644
--- a/include/linux/spinlock_api_up.h
+++ b/include/linux/spinlock_api_up.h
@@ -24,68 +24,77 @@
  * flags straight, to suppress compiler warnings of unused lock
  * variables, and to add the proper checker annotations:
  */
-#define ___LOCK(lock) \
-  do { __acquire(lock); (void)(lock); } while (0)
+#define ___LOCK_void(lock) \
+  do { (void)(lock); } while (0)
 
-#define __LOCK(lock) \
-  do { preempt_disable(); ___LOCK(lock); } while (0)
+#define ___LOCK_(lock) \
+  do { __acquire(lock); ___LOCK_void(lock); } while (0)
 
-#define __LOCK_BH(lock) \
-  do { __local_bh_disable_ip(_THIS_IP_, SOFTIRQ_LOCK_OFFSET); ___LOCK(lock); } while (0)
+#define ___LOCK_shared(lock) \
+  do { __acquire_shared(lock); ___LOCK_void(lock); } while (0)
 
-#define __LOCK_IRQ(lock) \
-  do { local_irq_disable(); __LOCK(lock); } while (0)
+#define __LOCK(lock, ...) \
+  do { preempt_disable(); ___LOCK_##__VA_ARGS__(lock); } while (0)
 
-#define __LOCK_IRQSAVE(lock, flags) \
-  do { local_irq_save(flags); __LOCK(lock); } while (0)
+#define __LOCK_BH(lock, ...) \
+  do { __local_bh_disable_ip(_THIS_IP_, SOFTIRQ_LOCK_OFFSET); ___LOCK_##__VA_ARGS__(lock); } while (0)
 
-#define ___UNLOCK(lock) \
+#define __LOCK_IRQ(lock, ...) \
+  do { local_irq_disable(); __LOCK(lock, ##__VA_ARGS__); } while (0)
+
+#define __LOCK_IRQSAVE(lock, flags, ...) \
+  do { local_irq_save(flags); __LOCK(lock, ##__VA_ARGS__); } while (0)
+
+#define ___UNLOCK_(lock) \
   do { __release(lock); (void)(lock); } while (0)
 
-#define __UNLOCK(lock) \
-  do { preempt_enable(); ___UNLOCK(lock); } while (0)
+#define ___UNLOCK_shared(lock) \
+  do { __release_shared(lock); (void)(lock); } while (0)
 
-#define __UNLOCK_BH(lock) \
+#define __UNLOCK(lock, ...) \
+  do { preempt_enable(); ___UNLOCK_##__VA_ARGS__(lock); } while (0)
+
+#define __UNLOCK_BH(lock, ...) \
   do { __local_bh_enable_ip(_THIS_IP_, SOFTIRQ_LOCK_OFFSET); \
-       ___UNLOCK(lock); } while (0)
+       ___UNLOCK_##__VA_ARGS__(lock); } while (0)
 
-#define __UNLOCK_IRQ(lock) \
-  do { local_irq_enable(); __UNLOCK(lock); } while (0)
+#define __UNLOCK_IRQ(lock, ...) \
+  do { local_irq_enable(); __UNLOCK(lock, ##__VA_ARGS__); } while (0)
 
-#define __UNLOCK_IRQRESTORE(lock, flags) \
-  do { local_irq_restore(flags); __UNLOCK(lock); } while (0)
+#define __UNLOCK_IRQRESTORE(lock, flags, ...) \
+  do { local_irq_restore(flags); __UNLOCK(lock, ##__VA_ARGS__); } while (0)
 
 #define _raw_spin_lock(lock)			__LOCK(lock)
 #define _raw_spin_lock_nested(lock, subclass)	__LOCK(lock)
-#define _raw_read_lock(lock)			__LOCK(lock)
+#define _raw_read_lock(lock)			__LOCK(lock, shared)
 #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_read_lock_bh(lock)			__LOCK_BH(lock, shared)
 #define _raw_write_lock_bh(lock)		__LOCK_BH(lock)
 #define _raw_spin_lock_irq(lock)		__LOCK_IRQ(lock)
-#define _raw_read_lock_irq(lock)		__LOCK_IRQ(lock)
+#define _raw_read_lock_irq(lock)		__LOCK_IRQ(lock, shared)
 #define _raw_write_lock_irq(lock)		__LOCK_IRQ(lock)
 #define _raw_spin_lock_irqsave(lock, flags)	__LOCK_IRQSAVE(lock, flags)
-#define _raw_read_lock_irqsave(lock, flags)	__LOCK_IRQSAVE(lock, flags)
+#define _raw_read_lock_irqsave(lock, flags)	__LOCK_IRQSAVE(lock, flags, shared)
 #define _raw_write_lock_irqsave(lock, flags)	__LOCK_IRQSAVE(lock, flags)
-#define _raw_spin_trylock(lock)			({ __LOCK(lock); 1; })
-#define _raw_read_trylock(lock)			({ __LOCK(lock); 1; })
-#define _raw_write_trylock(lock)			({ __LOCK(lock); 1; })
-#define _raw_spin_trylock_bh(lock)		({ __LOCK_BH(lock); 1; })
+#define _raw_spin_trylock(lock)			({ __LOCK(lock, void); 1; })
+#define _raw_read_trylock(lock)			({ __LOCK(lock, void); 1; })
+#define _raw_write_trylock(lock)			({ __LOCK(lock, void); 1; })
+#define _raw_spin_trylock_bh(lock)		({ __LOCK_BH(lock, void); 1; })
 #define _raw_spin_unlock(lock)			__UNLOCK(lock)
-#define _raw_read_unlock(lock)			__UNLOCK(lock)
+#define _raw_read_unlock(lock)			__UNLOCK(lock, shared)
 #define _raw_write_unlock(lock)			__UNLOCK(lock)
 #define _raw_spin_unlock_bh(lock)		__UNLOCK_BH(lock)
 #define _raw_write_unlock_bh(lock)		__UNLOCK_BH(lock)
-#define _raw_read_unlock_bh(lock)		__UNLOCK_BH(lock)
+#define _raw_read_unlock_bh(lock)		__UNLOCK_BH(lock, shared)
 #define _raw_spin_unlock_irq(lock)		__UNLOCK_IRQ(lock)
-#define _raw_read_unlock_irq(lock)		__UNLOCK_IRQ(lock)
+#define _raw_read_unlock_irq(lock)		__UNLOCK_IRQ(lock, shared)
 #define _raw_write_unlock_irq(lock)		__UNLOCK_IRQ(lock)
 #define _raw_spin_unlock_irqrestore(lock, flags) \
 					__UNLOCK_IRQRESTORE(lock, flags)
 #define _raw_read_unlock_irqrestore(lock, flags) \
-					__UNLOCK_IRQRESTORE(lock, flags)
+					__UNLOCK_IRQRESTORE(lock, flags, shared)
 #define _raw_write_unlock_irqrestore(lock, flags) \
 					__UNLOCK_IRQRESTORE(lock, flags)