locking/rwsem: Support Clang's context analysis

Add support for Clang's context analysis for rw_semaphore.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251219154418.3592607-18-elver@google.com

1 files changed, 64 insertions, 0 deletions

diff --git a/lib/test_context-analysis.c b/lib/test_context-analysis.c
index 39e03790c0f6..1c96c56cf873 100644
--- a/lib/test_context-analysis.c
+++ b/lib/test_context-analysis.c
@@ -8,6 +8,7 @@
 #include <linux/build_bug.h>
 #include <linux/mutex.h>
 #include <linux/rcupdate.h>
+#include <linux/rwsem.h>
 #include <linux/seqlock.h>
 #include <linux/spinlock.h>
 #include <linux/srcu.h>
@@ -262,6 +263,69 @@ static void __used test_seqlock_scoped(struct test_seqlock_data *d)
 	}
 }
 
+struct test_rwsem_data {
+	struct rw_semaphore sem;
+	int counter __guarded_by(&sem);
+};
+
+static void __used test_rwsem_init(struct test_rwsem_data *d)
+{
+	init_rwsem(&d->sem);
+	d->counter = 0;
+}
+
+static void __used test_rwsem_reader(struct test_rwsem_data *d)
+{
+	down_read(&d->sem);
+	(void)d->counter;
+	up_read(&d->sem);
+
+	if (down_read_trylock(&d->sem)) {
+		(void)d->counter;
+		up_read(&d->sem);
+	}
+}
+
+static void __used test_rwsem_writer(struct test_rwsem_data *d)
+{
+	down_write(&d->sem);
+	d->counter++;
+	up_write(&d->sem);
+
+	down_write(&d->sem);
+	d->counter++;
+	downgrade_write(&d->sem);
+	(void)d->counter;
+	up_read(&d->sem);
+
+	if (down_write_trylock(&d->sem)) {
+		d->counter++;
+		up_write(&d->sem);
+	}
+}
+
+static void __used test_rwsem_assert(struct test_rwsem_data *d)
+{
+	rwsem_assert_held_nolockdep(&d->sem);
+	d->counter++;
+}
+
+static void __used test_rwsem_guard(struct test_rwsem_data *d)
+{
+	{ guard(rwsem_read)(&d->sem); (void)d->counter; }
+	{ guard(rwsem_write)(&d->sem); d->counter++; }
+}
+
+static void __used test_rwsem_cond_guard(struct test_rwsem_data *d)
+{
+	scoped_cond_guard(rwsem_read_try, return, &d->sem) {
+		(void)d->counter;
+	}
+	scoped_cond_guard(rwsem_write_try, return, &d->sem) {
+		d->counter++;
+	}
+}
+
 struct test_bit_spinlock_data {
 	unsigned long bits;
 	int counter __guarded_by(__bitlock(3, &bits));