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, 128 insertions, 0 deletions

diff --git a/lib/test_context-analysis.c b/lib/test_context-analysis.c
index 68f075dec0e0..273fa9d34657 100644
--- a/lib/test_context-analysis.c
+++ b/lib/test_context-analysis.c
@@ -5,6 +5,7 @@
  */
 
 #include <linux/build_bug.h>
+#include <linux/spinlock.h>
 
 /*
  * Test that helper macros work as expected.
@@ -16,3 +17,130 @@ static void __used test_common_helpers(void)
 	BUILD_BUG_ON(context_unsafe((void)2, 3) != 3); /* does not swallow commas */
 	context_unsafe(do { } while (0)); /* works with void statements */
 }
+
+#define TEST_SPINLOCK_COMMON(class, type, type_init, type_lock, type_unlock, type_trylock, op)	\
+	struct test_##class##_data {								\
+		type lock;									\
+		int counter __guarded_by(&lock);						\
+		int *pointer __pt_guarded_by(&lock);						\
+	};											\
+	static void __used test_##class##_init(struct test_##class##_data *d)			\
+	{											\
+		type_init(&d->lock);								\
+		d->counter = 0;									\
+	}											\
+	static void __used test_##class(struct test_##class##_data *d)				\
+	{											\
+		unsigned long flags;								\
+		d->pointer++;									\
+		type_lock(&d->lock);								\
+		op(d->counter);									\
+		op(*d->pointer);								\
+		type_unlock(&d->lock);								\
+		type_lock##_irq(&d->lock);							\
+		op(d->counter);									\
+		op(*d->pointer);								\
+		type_unlock##_irq(&d->lock);							\
+		type_lock##_bh(&d->lock);							\
+		op(d->counter);									\
+		op(*d->pointer);								\
+		type_unlock##_bh(&d->lock);							\
+		type_lock##_irqsave(&d->lock, flags);						\
+		op(d->counter);									\
+		op(*d->pointer);								\
+		type_unlock##_irqrestore(&d->lock, flags);					\
+	}											\
+	static void __used test_##class##_trylock(struct test_##class##_data *d)		\
+	{											\
+		if (type_trylock(&d->lock)) {							\
+			op(d->counter);								\
+			type_unlock(&d->lock);							\
+		}										\
+	}											\
+	static void __used test_##class##_assert(struct test_##class##_data *d)			\
+	{											\
+		lockdep_assert_held(&d->lock);							\
+		op(d->counter);									\
+	}											\
+	static void __used test_##class##_guard(struct test_##class##_data *d)			\
+	{											\
+		{ guard(class)(&d->lock);		op(d->counter); }			\
+		{ guard(class##_irq)(&d->lock);		op(d->counter); }			\
+		{ guard(class##_irqsave)(&d->lock);	op(d->counter); }			\
+	}
+
+#define TEST_OP_RW(x) (x)++
+#define TEST_OP_RO(x) ((void)(x))
+
+TEST_SPINLOCK_COMMON(raw_spinlock,
+		     raw_spinlock_t,
+		     raw_spin_lock_init,
+		     raw_spin_lock,
+		     raw_spin_unlock,
+		     raw_spin_trylock,
+		     TEST_OP_RW);
+static void __used test_raw_spinlock_trylock_extra(struct test_raw_spinlock_data *d)
+{
+	unsigned long flags;
+
+	if (raw_spin_trylock_irq(&d->lock)) {
+		d->counter++;
+		raw_spin_unlock_irq(&d->lock);
+	}
+	if (raw_spin_trylock_irqsave(&d->lock, flags)) {
+		d->counter++;
+		raw_spin_unlock_irqrestore(&d->lock, flags);
+	}
+	scoped_cond_guard(raw_spinlock_try, return, &d->lock) {
+		d->counter++;
+	}
+}
+
+TEST_SPINLOCK_COMMON(spinlock,
+		     spinlock_t,
+		     spin_lock_init,
+		     spin_lock,
+		     spin_unlock,
+		     spin_trylock,
+		     TEST_OP_RW);
+static void __used test_spinlock_trylock_extra(struct test_spinlock_data *d)
+{
+	unsigned long flags;
+
+	if (spin_trylock_irq(&d->lock)) {
+		d->counter++;
+		spin_unlock_irq(&d->lock);
+	}
+	if (spin_trylock_irqsave(&d->lock, flags)) {
+		d->counter++;
+		spin_unlock_irqrestore(&d->lock, flags);
+	}
+	scoped_cond_guard(spinlock_try, return, &d->lock) {
+		d->counter++;
+	}
+}
+
+TEST_SPINLOCK_COMMON(write_lock,
+		     rwlock_t,
+		     rwlock_init,
+		     write_lock,
+		     write_unlock,
+		     write_trylock,
+		     TEST_OP_RW);
+static void __used test_write_trylock_extra(struct test_write_lock_data *d)
+{
+	unsigned long flags;
+
+	if (write_trylock_irqsave(&d->lock, flags)) {
+		d->counter++;
+		write_unlock_irqrestore(&d->lock, flags);
+	}
+}
+
+TEST_SPINLOCK_COMMON(read_lock,
+		     rwlock_t,
+		     rwlock_init,
+		     read_lock,
+		     read_unlock,
+		     read_trylock,
+		     TEST_OP_RO);