[PATCH v1 2/3] perf rwsem: Add thread-safety annotations

[Ian Rogers]

Add annotations used by clang's -Wthread-safety. Fix dsos compilation
errors caused by a lock of annotations.

Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
 tools/perf/util/dsos.c  |  3 +++
 tools/perf/util/mutex.h | 11 +++++++++++
 tools/perf/util/rwsem.c |  4 ++++
 tools/perf/util/rwsem.h | 10 +++++-----
 4 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c
index e0998e2a7c4e..4d213017d202 100644
--- a/tools/perf/util/dsos.c
+++ b/tools/perf/util/dsos.c
@@ -157,6 +157,7 @@ static struct dso *__dsos__find_by_longname_id(struct dsos *dsos,
 					       const char *name,
 					       const struct dso_id *id,
 					       bool write_locked)
+	SHARED_LOCKS_REQUIRED(dsos->lock)
 {
 	struct dsos__key key = {
 		.long_name = name,
@@ -262,6 +263,7 @@ static int dsos__find_id_cb(struct dso *dso, void *data)
 
 static struct dso *__dsos__find_id(struct dsos *dsos, const char *name, const struct dso_id *id,
 				   bool cmp_short, bool write_locked)
+	SHARED_LOCKS_REQUIRED(dsos->lock)
 {
 	struct dso *res;
 
@@ -338,6 +340,7 @@ static struct dso *__dsos__addnew_id(struct dsos *dsos, const char *name, const
 }
 
 static struct dso *__dsos__findnew_id(struct dsos *dsos, const char *name, const struct dso_id *id)
+	SHARED_LOCKS_REQUIRED(dsos->lock)
 {
 	struct dso *dso = __dsos__find_id(dsos, name, id, false, /*write_locked=*/true);
 
diff --git a/tools/perf/util/mutex.h b/tools/perf/util/mutex.h
index 62d258c71ded..38458f00846f 100644
--- a/tools/perf/util/mutex.h
+++ b/tools/perf/util/mutex.h
@@ -42,6 +42,12 @@
 /* Documents functions that acquire a lock in the body of a function, and do not release it. */
 #define EXCLUSIVE_LOCK_FUNCTION(...)  __attribute__((exclusive_lock_function(__VA_ARGS__)))
 
+/*
+ * Documents functions that acquire a shared (reader) lock in the body of a
+ * function, and do not release it.
+ */
+#define SHARED_LOCK_FUNCTION(...)  __attribute__((shared_lock_function(__VA_ARGS__)))
+
 /*
  * Documents functions that expect a lock to be held on entry to the function,
  * and release it in the body of the function.
@@ -55,6 +61,9 @@
 /* Documents a function that expects a mutex to be held prior to entry. */
 #define EXCLUSIVE_LOCKS_REQUIRED(...) __attribute__((exclusive_locks_required(__VA_ARGS__)))
 
+/* Documents a function that expects a shared (reader) lock to be held prior to entry. */
+#define SHARED_LOCKS_REQUIRED(...) __attribute__((shared_locks_required(__VA_ARGS__)))
+
 /* Turns off thread safety checking within the body of a particular function. */
 #define NO_THREAD_SAFETY_ANALYSIS __attribute__((no_thread_safety_analysis))
 
@@ -66,9 +75,11 @@
 #define LOCKS_EXCLUDED(...)
 #define LOCK_RETURNED(x)
 #define EXCLUSIVE_LOCK_FUNCTION(...)
+#define SHARED_LOCK_FUNCTION(...)
 #define UNLOCK_FUNCTION(...)
 #define EXCLUSIVE_TRYLOCK_FUNCTION(...)
 #define EXCLUSIVE_LOCKS_REQUIRED(...)
+#define SHARED_LOCKS_REQUIRED(...)
 #define NO_THREAD_SAFETY_ANALYSIS
 
 #endif
diff --git a/tools/perf/util/rwsem.c b/tools/perf/util/rwsem.c
index 5109167f27f7..9d26832398db 100644
--- a/tools/perf/util/rwsem.c
+++ b/tools/perf/util/rwsem.c
@@ -27,6 +27,7 @@ int exit_rwsem(struct rw_semaphore *sem)
 }
 
 int down_read(struct rw_semaphore *sem)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 #if RWS_ERRORCHECK
 	mutex_lock(&sem->mtx);
@@ -37,6 +38,7 @@ int down_read(struct rw_semaphore *sem)
 }
 
 int up_read(struct rw_semaphore *sem)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 #if RWS_ERRORCHECK
 	mutex_unlock(&sem->mtx);
@@ -47,6 +49,7 @@ int up_read(struct rw_semaphore *sem)
 }
 
 int down_write(struct rw_semaphore *sem)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 #if RWS_ERRORCHECK
 	mutex_lock(&sem->mtx);
@@ -57,6 +60,7 @@ int down_write(struct rw_semaphore *sem)
 }
 
 int up_write(struct rw_semaphore *sem)
+	NO_THREAD_SAFETY_ANALYSIS
 {
 #if RWS_ERRORCHECK
 	mutex_unlock(&sem->mtx);
diff --git a/tools/perf/util/rwsem.h b/tools/perf/util/rwsem.h
index ef5cbc31d967..b102d8143181 100644
--- a/tools/perf/util/rwsem.h
+++ b/tools/perf/util/rwsem.h
@@ -10,7 +10,7 @@
  */
 #define RWS_ERRORCHECK 0
 
-struct rw_semaphore {
+struct LOCKABLE rw_semaphore {
 #if RWS_ERRORCHECK
 	struct mutex mtx;
 #else
@@ -21,10 +21,10 @@ struct rw_semaphore {
 int init_rwsem(struct rw_semaphore *sem);
 int exit_rwsem(struct rw_semaphore *sem);
 
-int down_read(struct rw_semaphore *sem);
-int up_read(struct rw_semaphore *sem);
+int down_read(struct rw_semaphore *sem) SHARED_LOCK_FUNCTION(sem);
+int up_read(struct rw_semaphore *sem) UNLOCK_FUNCTION(sem);
 
-int down_write(struct rw_semaphore *sem);
-int up_write(struct rw_semaphore *sem);
+int down_write(struct rw_semaphore *sem) EXCLUSIVE_LOCK_FUNCTION(sem);
+int up_write(struct rw_semaphore *sem) UNLOCK_FUNCTION(sem);
 
 #endif /* _PERF_RWSEM_H */
-- 
2.49.0.1101.gccaa498523-goog