[cfe-dev] ThreadSafetyAnalysis in C code

[Marco Elver via cfe-dev]

Hello,

We are interested in applying ThreadSafetyAnalysis to C code
(specifically the Linux kernel).

However, the very common usecase of declaring a struct member to be
protected by another lockable struct member inside the same struct does
not work (see addition to test below). This results in an error:

	clang/test/Sema/warn-thread-safety-analysis.c:36:24: error: use of undeclared identifier 'mu'
	  int data1 GUARDED_BY(mu);
			       ^
	clang/test/Sema/warn-thread-safety-analysis.c:38:24: error: use of undeclared identifier 'mu'
	  int data2 GUARDED_BY(mu);

AFAIK, this is the main limitation preventing us to use it on the Linux
kernel.

Does anyone know what's going on here?

Thanks,
-- Marco

------ >8 ------

diff --git a/clang/test/Sema/warn-thread-safety-analysis.c b/clang/test/Sema/warn-thread-safety-analysis.c
index a45fb8e0f382..6b75db4c246e 100644
--- a/clang/test/Sema/warn-thread-safety-analysis.c
+++ b/clang/test/Sema/warn-thread-safety-analysis.c
@@ -31,6 +31,13 @@ struct Foo {
   struct Mutex *mu_;
 };
 
+// Struct with mutex protecting data within.
+struct Bar {
+  int data1 GUARDED_BY(mu);
+  struct Mutex mu;
+  int data2 GUARDED_BY(mu);
+};
+
 // Declare mutex lock/unlock functions.
 void mutex_exclusive_lock(struct Mutex *mu) EXCLUSIVE_LOCK_FUNCTION(mu);
 void mutex_shared_lock(struct Mutex *mu) SHARED_LOCK_FUNCTION(mu);
@@ -46,6 +53,7 @@ int a_ GUARDED_BY(foo_.mu_);
 int *b_ PT_GUARDED_BY(foo_.mu_) = &a_;
 int c_ GUARDED_VAR;
 int *d_ PT_GUARDED_VAR = &c_;
+struct Bar bar_;
 
 // Define test functions.
 int Foo_fun1(int i) SHARED_LOCKS_REQUIRED(mu2) EXCLUSIVE_LOCKS_REQUIRED(mu1) {
@@ -117,6 +125,13 @@ int main() {
   (void)(*d_ == 1);
   mutex_unlock(foo_.mu_);
 
+  bar_.data1 = 0; // expected-warning{{writing variable 'data1' requires holding mutex 'bar_.mu' exclusively}}
+  bar_.data2 = 0; // expected-warning{{writing variable 'data2' requires holding mutex 'bar_.mu' exclusively}}
+  mutex_exclusive_lock(&bar_.mu);
+  bar_.data1 = 1;
+  bar_.data2 = 1;
+  mutex_unlock(&bar_.mu);
+
   mutex_exclusive_lock(&mu1);    // expected-note {{mutex acquired here}}
   mutex_shared_unlock(&mu1);     // expected-warning {{releasing mutex 'mu1' using shared access, expected exclusive access}}
                                  // expected-note at -1{{mutex released here}}