[cfe-dev] [PATCH 2/2] Thread-safety: Add test for -Wthread-safety check for C.
Alex Wang
alexw at nicira.com
Thu Jul 25 18:03:33 PDT 2013
Hey David,
Sorry for the delayed reply and thanks for your explanation,
I did modification below to add this new "c_wthread_safety" so that it can
be checked by "__has_feature()". Is this what you mean?
Hope to hear more comments,
Kind Regards,
Alex Wang,
Index: lib/Lex/PPMacroExpansion.cpp
===================================================================
--- lib/Lex/PPMacroExpansion.cpp (revision 186655)
+++ lib/Lex/PPMacroExpansion.cpp (working copy)
@@ -727,6 +727,7 @@
.Case("attribute_unavailable_with_message", true)
.Case("attribute_unused_on_fields", true)
.Case("blocks", LangOpts.Blocks)
+ .Case("c_wthread_safety", true)
.Case("cxx_exceptions", LangOpts.Exceptions)
.Case("cxx_rtti", LangOpts.RTTI)
.Case("enumerator_attributes", true)
On Thu, Jul 25, 2013 at 2:57 PM, David Chisnall <David.Chisnall at cl.cam.ac.uk
> wrote:
> Hi Alex,
>
> I think you misunderstand. If I want to use these in, for example,
> pthread.h, then I want to make sure that the attributes are only used when
> a compiler that knows about them is being used. Clang provides the
> __has_feature() mechanism in the preprocessor for these checks at a coarse
> granularity, so that library headers can conditionally expose compiler and
> compiler-version specific features.
>
> How do I check, from within a header, that I am using a version of clang
> that supports thread-safety annotations in C?
>
> David
>
> On 25 Jul 2013, at 18:04, Alex Wang <alexw at nicira.com> wrote:
>
> > Hey David,
> >
> > Thanks for your reply, please correct me if my understanding is wrong,
> >
> > Since I only use the thread safety attributes defined in clang, there
> should be no requirement on gcc extension.
> >
> > Actually, I think it does not make very much sense to check for each of
> the attributes individually, since we only use these attributes for
> semantic analysis and your cpp test (warn-thread-safety-analysis.cpp) is
> every detailed.
> >
> > Kind Regards,
> > Alex Wang,
> >
> >
> > On Thu, Jul 25, 2013 at 4:31 AM, David Chisnall <
> David.Chisnall at cl.cam.ac.uk> wrote:
> > Hi,
> >
> > What is the __has_extension() variable to check for support for these?
> Or do we need to check for each of the attributes individually?
> >
> > David
> >
> > On 25 Jul 2013, at 02:16, Alex Wang <alexw at nicira.com> wrote:
> >
> > > This commit adds test to the -Wthread-safety check for C code.
> > >
> > > Co-authored-by: Ethan Jackson <ethan at nicira.com>
> > > Signed-off-by: Alex Wang <alexw at nicira.com>
> > >
> > > Index: warn-thread-safety-analysis.c
> > > ===================================================================
> > > --- warn-thread-safety-analysis.c (revision 0)
> > > +++ warn-thread-safety-analysis.c (revision 0)
> > > @@ -0,0 +1,132 @@
> > > +// RUN: %clang -fsyntax-only -verify -Wthread-safety
> -Wthread-safety-beta -fcxx-exceptions %s
> > > +
> > > +#include <assert.h>
> > > +
> > > +#define LOCKABLE __attribute__ ((lockable))
> > > +#define SCOPED_LOCKABLE __attribute__ ((scoped_lockable))
> > > +#define GUARDED_BY(x) __attribute__ ((guarded_by(x)))
> > > +#define GUARDED_VAR __attribute__ ((guarded_var))
> > > +#define PT_GUARDED_BY(x) __attribute__ ((pt_guarded_by(x)))
> > > +#define PT_GUARDED_VAR __attribute__ ((pt_guarded_var))
> > > +#define ACQUIRED_AFTER(...) __attribute__
> ((acquired_after(__VA_ARGS__)))
> > > +#define ACQUIRED_BEFORE(...) __attribute__
> ((acquired_before(__VA_ARGS__)))
> > > +#define EXCLUSIVE_LOCK_FUNCTION(...) __attribute__
> ((exclusive_lock_function(__VA_ARGS__)))
> > > +#define SHARED_LOCK_FUNCTION(...) __attribute__
> ((shared_lock_function(__VA_ARGS__)))
> > > +#define ASSERT_EXCLUSIVE_LOCK(...) __attribute__
> ((assert_exclusive_lock(__VA_ARGS__)))
> > > +#define ASSERT_SHARED_LOCK(...) __attribute__
> ((assert_shared_lock(__VA_ARGS__)))
> > > +#define EXCLUSIVE_TRYLOCK_FUNCTION(...) __attribute__
> ((exclusive_trylock_function(__VA_ARGS__)))
> > > +#define SHARED_TRYLOCK_FUNCTION(...) __attribute__
> ((shared_trylock_function(__VA_ARGS__)))
> > > +#define UNLOCK_FUNCTION(...) __attribute__
> ((unlock_function(__VA_ARGS__)))
> > > +#define LOCK_RETURNED(x) __attribute__ ((lock_returned(x)))
> > > +#define LOCKS_EXCLUDED(...) __attribute__
> ((locks_excluded(__VA_ARGS__)))
> > > +#define EXCLUSIVE_LOCKS_REQUIRED(...) \
> > > + __attribute__ ((exclusive_locks_required(__VA_ARGS__)))
> > > +#define SHARED_LOCKS_REQUIRED(...) \
> > > + __attribute__ ((shared_locks_required(__VA_ARGS__)))
> > > +#define NO_THREAD_SAFETY_ANALYSIS __attribute__
> ((no_thread_safety_analysis))
> > > +
> > > +// Define the mutex struct.
> > > +// Simplified only for test purpose.
> > > +struct LOCKABLE Mutex {};
> > > +
> > > +struct Foo {
> > > + struct Mutex *mu_;
> > > +};
> > > +
> > > +// Define 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) {
> > > +}
> > > +
> > > +void mutex_unlock(struct Mutex *mu) UNLOCK_FUNCTION(mu) {
> > > +}
> > > +
> > > +// Define global variables.
> > > +struct Mutex mu1;
> > > +struct Mutex mu2 ACQUIRED_AFTER(mu1);
> > > +struct Foo foo_ = {&mu1};
> > > +int a_ GUARDED_BY(foo_.mu_);
> > > +int *b_ PT_GUARDED_BY(foo_.mu_) = &a_;
> > > +int c_ GUARDED_VAR;
> > > +int *d_ PT_GUARDED_VAR = &c_;
> > > +
> > > +// Define test functions.
> > > +int Foo_fun1(int i) SHARED_LOCKS_REQUIRED(mu2)
> EXCLUSIVE_LOCKS_REQUIRED(mu1) {
> > > + return i;
> > > +}
> > > +
> > > +int Foo_fun2(int i) EXCLUSIVE_LOCKS_REQUIRED(mu2)
> SHARED_LOCKS_REQUIRED(mu1) {
> > > + return i;
> > > +}
> > > +
> > > +int Foo_func3(int i) LOCKS_EXCLUDED(mu1, mu2) {
> > > + return i;
> > > +}
> > > +
> > > +static int Bar_fun1(int i) EXCLUSIVE_LOCKS_REQUIRED(mu1) {
> > > + return i;
> > > +}
> > > +
> > > +void set_value(int *a, int value) EXCLUSIVE_LOCKS_REQUIRED(foo_.mu_) {
> > > + *a = value;
> > > +}
> > > +
> > > +int get_value(int *p) SHARED_LOCKS_REQUIRED(foo_.mu_){
> > > + return *p;
> > > +}
> > > +
> > > +int main() {
> > > +
> > > + Foo_fun1(1); // \
> > > + // expected-warning{{calling function 'Foo_fun1' requires
> shared lock on 'mu2'}}
> > > + // expected-warning{{calling function 'Foo_fun1' requires
> exclusive lock on 'mu1'}}
> > > +
> > > + mutex_exclusive_lock(&mu1);
> > > + mutex_shared_lock(&mu2);
> > > + Foo_fun1(1);
> > > +
> > > + mutex_shared_lock(&mu1); // \
> > > + // expected-warning{{locking 'mu1' that is already locked}}
> > > + mutex_unlock(&mu1);
> > > + mutex_unlock(&mu2);
> > > + mutex_shared_lock(&mu1);
> > > + mutex_exclusive_lock(&mu2);
> > > + Foo_fun2(2);
> > > +
> > > + mutex_unlock(&mu2);
> > > + mutex_unlock(&mu1);
> > > + mutex_exclusive_lock(&mu1);
> > > + Bar_fun1(3);
> > > + mutex_unlock(&mu1);
> > > +
> > > + mutex_exclusive_lock(&mu1);
> > > + Foo_func3(4); // \
> > > + // expected-warning{{cannot call function 'Foo_func3' while
> mutex 'mu1' is locked}}
> > > + mutex_unlock(&mu1);
> > > +
> > > + Foo_func3(5);
> > > +
> > > + set_value(&a_, 0); // \
> > > + // expected-warning{{calling function 'setA' requires exclusive
> lock on 'foo_.mu_'}}
> > > + get_value(b_); // \
> > > + // expected-warning{{calling function 'getB' requires shared
> lock on 'foo_.mu_'}}
> > > + mutex_exclusive_lock(foo_.mu_);
> > > + set_value(&a_, 1);
> > > + mutex_unlock(foo_.mu_);
> > > + mutex_shared_lock(foo_.mu_);
> > > + assert(get_value(b_) == 1);
> > > + mutex_unlock(foo_.mu_);
> > > +
> > > + c_ = 0; // \
> > > + // expected-warning{{writing variable 'c_' requires locking any
> mutex exclusively}}
> > > + assert(*d_ == 0); // \
> > > + // expected-warning{{reading the value pointed to by 'd_'
> requires locking any mutex}}
> > > + mutex_exclusive_lock(foo_.mu_);
> > > + c_ = 1;
> > > + assert(*d_ == 1);
> > > + mutex_unlock(foo_.mu_);
> > > +
> > > + return 0;
> > > +}
> > > _______________________________________________
> > > cfe-dev mailing list
> > > cfe-dev at cs.uiuc.edu
> > > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
> >
> >
>
>
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