[compiler-rt] r265659 - [tsan] Fix synchronization in dispatch_sync
Kuba Brecka via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 7 04:33:45 PDT 2016
Author: kuba.brecka
Date: Thu Apr 7 06:33:44 2016
New Revision: 265659
URL: http://llvm.org/viewvc/llvm-project?rev=265659&view=rev
Log:
[tsan] Fix synchronization in dispatch_sync
In the interceptor for dispatch_sync, we're currently missing synchronization between the callback and the code *after* the call to dispatch_sync. This patch fixes this by adding an extra release+acquire pair to dispatch_sync() and similar APIs. Added a testcase.
Differential Revision: http://reviews.llvm.org/D18502
Added:
compiler-rt/trunk/test/tsan/Darwin/gcd-blocks.mm
Modified:
compiler-rt/trunk/lib/tsan/rtl/tsan_libdispatch_mac.cc
Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_libdispatch_mac.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_libdispatch_mac.cc?rev=265659&r1=265658&r2=265659&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_libdispatch_mac.cc (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_libdispatch_mac.cc Thu Apr 7 06:33:44 2016
@@ -33,8 +33,10 @@ typedef struct {
dispatch_queue_t queue;
void *orig_context;
dispatch_function_t orig_work;
- uptr object_to_acquire;
+ uptr sync_object;
dispatch_object_t object_to_release;
+ bool free_context_in_callback;
+ bool release_sync_object_in_callback;
} tsan_block_context_t;
// The offsets of different fields of the dispatch_queue_t structure, exported
@@ -75,15 +77,18 @@ static tsan_block_context_t *AllocContex
new_context->queue = queue;
new_context->orig_context = orig_context;
new_context->orig_work = orig_work;
- new_context->object_to_acquire = (uptr)new_context;
+ new_context->sync_object = (uptr)new_context;
new_context->object_to_release = nullptr;
+ new_context->free_context_in_callback = true;
+ new_context->release_sync_object_in_callback = false;
return new_context;
}
-static void dispatch_callback_wrap_acquire(void *param) {
- SCOPED_INTERCEPTOR_RAW(dispatch_async_f_callback_wrap);
+static void dispatch_callback_wrap(void *param) {
+ SCOPED_INTERCEPTOR_RAW(dispatch_callback_wrap);
tsan_block_context_t *context = (tsan_block_context_t *)param;
- Acquire(thr, pc, context->object_to_acquire);
+
+ Acquire(thr, pc, context->sync_object);
// Extra retain/release is required for dispatch groups. We use the group
// itself to synchronize, but in a notification (dispatch_group_notify
@@ -98,7 +103,11 @@ static void dispatch_callback_wrap_acqui
context->orig_work(context->orig_context);
SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
if (IsQueueSerial(context->queue)) Release(thr, pc, (uptr)context->queue);
- user_free(thr, pc, context);
+
+ if (context->release_sync_object_in_callback)
+ Release(thr, pc, context->sync_object);
+
+ if (context->free_context_in_callback) user_free(thr, pc, context);
}
static void invoke_and_release_block(void *param) {
@@ -110,15 +119,31 @@ static void invoke_and_release_block(voi
#define DISPATCH_INTERCEPT_B(name) \
TSAN_INTERCEPTOR(void, name, dispatch_queue_t q, dispatch_block_t block) { \
SCOPED_TSAN_INTERCEPTOR(name, q, block); \
- SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
dispatch_block_t heap_block = Block_copy(block); \
- SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
tsan_block_context_t *new_context = \
AllocContext(thr, pc, q, heap_block, &invoke_and_release_block); \
Release(thr, pc, (uptr)new_context); \
- SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
- REAL(name##_f)(q, new_context, dispatch_callback_wrap_acquire); \
- SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
+ REAL(name##_f)(q, new_context, dispatch_callback_wrap); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
+ }
+
+#define DISPATCH_INTERCEPT_SYNC_B(name) \
+ TSAN_INTERCEPTOR(void, name, dispatch_queue_t q, dispatch_block_t block) { \
+ SCOPED_TSAN_INTERCEPTOR(name, q, block); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
+ dispatch_block_t heap_block = Block_copy(block); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
+ tsan_block_context_t new_context = { \
+ q, heap_block, &invoke_and_release_block, 0, 0, false, true}; \
+ new_context.sync_object = (uptr)&new_context; \
+ Release(thr, pc, (uptr)&new_context); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
+ REAL(name##_f)(q, &new_context, dispatch_callback_wrap); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
+ Acquire(thr, pc, (uptr)&new_context); \
}
#define DISPATCH_INTERCEPT_F(name) \
@@ -128,9 +153,22 @@ static void invoke_and_release_block(voi
tsan_block_context_t *new_context = \
AllocContext(thr, pc, q, context, work); \
Release(thr, pc, (uptr)new_context); \
- SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
- REAL(name)(q, new_context, dispatch_callback_wrap_acquire); \
- SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
+ REAL(name)(q, new_context, dispatch_callback_wrap); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
+ }
+
+#define DISPATCH_INTERCEPT_SYNC_F(name) \
+ TSAN_INTERCEPTOR(void, name, dispatch_queue_t q, void *context, \
+ dispatch_function_t work) { \
+ SCOPED_TSAN_INTERCEPTOR(name, q, context, work); \
+ tsan_block_context_t new_context = {q, context, work, 0, 0, false, true}; \
+ new_context.sync_object = (uptr)&new_context; \
+ Release(thr, pc, (uptr)&new_context); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START(); \
+ REAL(name)(q, &new_context, dispatch_callback_wrap); \
+ SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END(); \
+ Acquire(thr, pc, (uptr)&new_context); \
}
// We wrap dispatch_async, dispatch_sync and friends where we allocate a new
@@ -141,10 +179,10 @@ DISPATCH_INTERCEPT_B(dispatch_async)
DISPATCH_INTERCEPT_B(dispatch_barrier_async)
DISPATCH_INTERCEPT_F(dispatch_async_f)
DISPATCH_INTERCEPT_F(dispatch_barrier_async_f)
-DISPATCH_INTERCEPT_B(dispatch_sync)
-DISPATCH_INTERCEPT_B(dispatch_barrier_sync)
-DISPATCH_INTERCEPT_F(dispatch_sync_f)
-DISPATCH_INTERCEPT_F(dispatch_barrier_sync_f)
+DISPATCH_INTERCEPT_SYNC_B(dispatch_sync)
+DISPATCH_INTERCEPT_SYNC_B(dispatch_barrier_sync)
+DISPATCH_INTERCEPT_SYNC_F(dispatch_sync_f)
+DISPATCH_INTERCEPT_SYNC_F(dispatch_barrier_sync_f)
// GCD's dispatch_once implementation has a fast path that contains a racy read
// and it's inlined into user's code. Furthermore, this fast path doesn't
@@ -253,30 +291,30 @@ TSAN_INTERCEPTOR(void, dispatch_group_no
SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
tsan_block_context_t *new_context =
AllocContext(thr, pc, q, heap_block, &invoke_and_release_block);
- new_context->object_to_acquire = (uptr)group;
+ new_context->sync_object = (uptr)group;
- // Will be released in dispatch_callback_wrap_acquire.
+ // Will be released in dispatch_callback_wrap.
new_context->object_to_release = group;
dispatch_retain(group);
Release(thr, pc, (uptr)group);
REAL(dispatch_group_notify_f)(group, q, new_context,
- dispatch_callback_wrap_acquire);
+ dispatch_callback_wrap);
}
TSAN_INTERCEPTOR(void, dispatch_group_notify_f, dispatch_group_t group,
dispatch_queue_t q, void *context, dispatch_function_t work) {
SCOPED_TSAN_INTERCEPTOR(dispatch_group_notify_f, group, q, context, work);
tsan_block_context_t *new_context = AllocContext(thr, pc, q, context, work);
- new_context->object_to_acquire = (uptr)group;
+ new_context->sync_object = (uptr)group;
- // Will be released in dispatch_callback_wrap_acquire.
+ // Will be released in dispatch_callback_wrap.
new_context->object_to_release = group;
dispatch_retain(group);
Release(thr, pc, (uptr)group);
REAL(dispatch_group_notify_f)(group, q, new_context,
- dispatch_callback_wrap_acquire);
+ dispatch_callback_wrap);
}
} // namespace __tsan
Added: compiler-rt/trunk/test/tsan/Darwin/gcd-blocks.mm
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/tsan/Darwin/gcd-blocks.mm?rev=265659&view=auto
==============================================================================
--- compiler-rt/trunk/test/tsan/Darwin/gcd-blocks.mm (added)
+++ compiler-rt/trunk/test/tsan/Darwin/gcd-blocks.mm Thu Apr 7 06:33:44 2016
@@ -0,0 +1,34 @@
+// RUN: %clang_tsan %s -o %t -framework Foundation
+// RUN: %env_tsan_opts=ignore_interceptors_accesses=1 %run %t 2>&1 | FileCheck %s
+
+#import <Foundation/Foundation.h>
+
+int main() {
+ fprintf(stderr, "start\n");
+
+ dispatch_queue_t background_q = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
+ dispatch_queue_t main_q = dispatch_get_main_queue();
+
+ dispatch_async(background_q, ^{
+ __block long block_var = 0;
+
+ dispatch_sync(main_q, ^{
+ block_var = 42;
+ });
+
+ fprintf(stderr, "block_var = %ld\n", block_var);
+
+ dispatch_sync(dispatch_get_main_queue(), ^{
+ CFRunLoopStop(CFRunLoopGetCurrent());
+ });
+ });
+
+ CFRunLoopRun();
+ fprintf(stderr, "done\n");
+}
+
+// CHECK: start
+// CHECK: block_var = 42
+// CHECK: done
+// CHECK-NOT: WARNING: ThreadSanitizer
+// CHECK-NOT: CHECK failed
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