[sanitizer] allow to store the lock context (stack trace id) with all currently held locks in a thread. This will allow the deadlock detector to provide better warnings (more changes to go)

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@204039 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 84 insertions, 12 deletions

diff --git a/lib/sanitizer_common/sanitizer_deadlock_detector.h b/lib/sanitizer_common/sanitizer_deadlock_detector.h
index dfaacb3d2..a37310178 100644
--- a/lib/sanitizer_common/sanitizer_deadlock_detector.h
+++ b/lib/sanitizer_common/sanitizer_deadlock_detector.h
@@ -41,6 +41,7 @@ class DeadlockDetectorTLS {
     bv_.clear();
     epoch_ = 0;
     n_recursive_locks = 0;
+    n_all_locks_ = 0;
   }
 
   bool empty() const { return bv_.empty(); }
@@ -54,7 +55,7 @@ class DeadlockDetectorTLS {
   uptr getEpoch() const { return epoch_; }
 
   // Returns true if this is the first (non-recursive) acquisition of this lock.
-  bool addLock(uptr lock_id, uptr current_epoch) {
+  bool addLock(uptr lock_id, uptr current_epoch, u32 stk) {
     // Printf("addLock: %zx %zx\n", lock_id, current_epoch);
     CHECK_EQ(epoch_, current_epoch);
     if (!bv_.setBit(lock_id)) {
@@ -63,6 +64,12 @@ class DeadlockDetectorTLS {
       recursive_locks[n_recursive_locks++] = lock_id;
       return false;
     }
+    if (stk) {
+      CHECK_LT(n_all_locks_, ARRAY_SIZE(all_locks_with_contexts_));
+      LockWithContext &l = all_locks_with_contexts_[n_all_locks_++];
+      l.lock = static_cast<u32>(lock_id);  // lock_id is small index into bv_.
+      l.stk = stk;
+    }
     return true;
   }
 
@@ -78,6 +85,23 @@ class DeadlockDetectorTLS {
     }
     // Printf("remLock: %zx %zx\n", lock_id, epoch_);
     CHECK(bv_.clearBit(lock_id));
+    if (n_all_locks_) {
+      for (sptr i = n_all_locks_ - 1; i >= 0; i--) {
+        if (all_locks_with_contexts_[i].lock == static_cast<u32>(lock_id)) {
+          Swap(all_locks_with_contexts_[i],
+               all_locks_with_contexts_[n_all_locks_ - 1]);
+          n_all_locks_--;
+          break;
+        }
+      }
+    }
+  }
+
+  u32 findLockContext(uptr lock_id) {
+    for (uptr i = 0; i < n_all_locks_; i++)
+      if (all_locks_with_contexts_[i].lock == static_cast<u32>(lock_id))
+        return all_locks_with_contexts_[i].stk;
+    return 0;
   }
 
   const BV &getLocks(uptr current_epoch) const {
@@ -90,6 +114,12 @@ class DeadlockDetectorTLS {
   uptr epoch_;
   uptr recursive_locks[64];
   uptr n_recursive_locks;
+  struct LockWithContext {
+    u32 lock;
+    u32 stk;
+  };
+  LockWithContext all_locks_with_contexts_[64];
+  uptr n_all_locks_;
 };
 
 // DeadlockDetector.
@@ -165,11 +195,15 @@ class DeadlockDetector {
     return g_.isReachable(cur_idx, dtls->getLocks(current_epoch_));
   }
 
+  u32 findLockContext(DeadlockDetectorTLS<BV> *dtls, uptr node) {
+    return dtls->findLockContext(nodeToIndex(node));
+  }
+
   // Add cur_node to the set of locks held currently by dtls.
-  void onLockAfter(DeadlockDetectorTLS<BV> *dtls, uptr cur_node) {
+  void onLockAfter(DeadlockDetectorTLS<BV> *dtls, uptr cur_node, u32 stk = 0) {
     ensureCurrentEpoch(dtls);
     uptr cur_idx = nodeToIndex(cur_node);
-    dtls->addLock(cur_idx, current_epoch_);
+    dtls->addLock(cur_idx, current_epoch_, stk);
   }
 
   // Experimental *racy* fast path function.
@@ -189,7 +223,7 @@ class DeadlockDetector {
   // returns the number of added edges, and puts the sources of added edges
   // into added_edges[].
   // Should be called before onLockAfter.
-  uptr addEdges(DeadlockDetectorTLS<BV> *dtls, uptr cur_node, u32 stk) {
+  uptr addEdges(DeadlockDetectorTLS<BV> *dtls, uptr cur_node, u32 stk = 0) {
     ensureCurrentEpoch(dtls);
     uptr cur_idx = nodeToIndex(cur_node);
     uptr added_edges[40];
@@ -215,11 +249,11 @@ class DeadlockDetector {
 
   // Test-only function. Handles the before/after lock events,
   // returns true if there is a cycle.
-  bool onLock(DeadlockDetectorTLS<BV> *dtls, uptr cur_node) {
+  bool onLock(DeadlockDetectorTLS<BV> *dtls, uptr cur_node, u32 stk = 0) {
     ensureCurrentEpoch(dtls);
     bool is_reachable = !isHeld(dtls, cur_node) && onLockBefore(dtls, cur_node);
     addEdges(dtls, cur_node, 0);
-    onLockAfter(dtls, cur_node);
+    onLockAfter(dtls, cur_node, stk);
     return is_reachable;
   }
 
@@ -228,20 +262,20 @@ class DeadlockDetector {
   // to add this lock to the currently held locks, but we should not try to
   // change the lock graph or to detect a cycle.  We may want to investigate
   // whether a more aggressive strategy is possible for try_lock.
-  bool onTryLock(DeadlockDetectorTLS<BV> *dtls, uptr cur_node) {
+  bool onTryLock(DeadlockDetectorTLS<BV> *dtls, uptr cur_node, u32 stk = 0) {
     ensureCurrentEpoch(dtls);
     uptr cur_idx = nodeToIndex(cur_node);
-    dtls->addLock(cur_idx, current_epoch_);
+    dtls->addLock(cur_idx, current_epoch_, stk);
     return false;
   }
 
   // Returns true iff dtls is empty (no locks are currently held) and we can
   // add the node to the currently held locks w/o chanding the global state.
   // This operation is thread-safe as it only touches the dtls.
-  bool onFirstLock(DeadlockDetectorTLS<BV> *dtls, uptr node) {
+  bool onFirstLock(DeadlockDetectorTLS<BV> *dtls, uptr node, u32 stk = 0) {
     if (!dtls->empty()) return false;
     if (dtls->getEpoch() && dtls->getEpoch() == nodeToEpoch(node)) {
-      dtls->addLock(nodeToIndexUnchecked(node), nodeToEpoch(node));
+      dtls->addLock(nodeToIndexUnchecked(node), nodeToEpoch(node), stk);
       return true;
     }
     return false;
@@ -274,9 +308,9 @@ class DeadlockDetector {
   // Returns true on success.
   // This operation is thread-safe as it only touches the dtls
   // (modulo racy nature of hasAllEdges).
-  bool onLockFast(DeadlockDetectorTLS<BV> *dtls, uptr node) {
+  bool onLockFast(DeadlockDetectorTLS<BV> *dtls, uptr node, u32 stk = 0) {
     if (hasAllEdges(dtls, node)) {
-      dtls->addLock(nodeToIndexUnchecked(node), nodeToEpoch(node));
+      dtls->addLock(nodeToIndexUnchecked(node), nodeToEpoch(node), 0);
       return true;
     }
     return false;
diff --git a/lib/sanitizer_common/tests/sanitizer_deadlock_detector_test.cc b/lib/sanitizer_common/tests/sanitizer_deadlock_detector_test.cc
index 36d384531..a11b5a514 100644
--- a/lib/sanitizer_common/tests/sanitizer_deadlock_detector_test.cc
+++ b/lib/sanitizer_common/tests/sanitizer_deadlock_detector_test.cc
@@ -406,3 +406,41 @@ void RunRecusriveLockTest() {
 TEST(DeadlockDetector, RecusriveLockTest) {
   RunRecusriveLockTest<BV2>();
 }
+
+template <class BV>
+void RunLockContextTest() {
+  ScopedDD<BV> sdd;
+  DeadlockDetector<BV> &d = *sdd.dp;
+  DeadlockDetectorTLS<BV> &dtls = sdd.dtls;
+
+  uptr l0 = d.newNode(0);
+  uptr l1 = d.newNode(0);
+  uptr l2 = d.newNode(0);
+  uptr l3 = d.newNode(0);
+  uptr l4 = d.newNode(0);
+  EXPECT_FALSE(d.onLock(&dtls, l0, 10));
+  EXPECT_FALSE(d.onLock(&dtls, l1, 11));
+  EXPECT_FALSE(d.onLock(&dtls, l2, 12));
+  EXPECT_FALSE(d.onLock(&dtls, l3, 13));
+  EXPECT_EQ(10U, d.findLockContext(&dtls, l0));
+  EXPECT_EQ(11U, d.findLockContext(&dtls, l1));
+  EXPECT_EQ(12U, d.findLockContext(&dtls, l2));
+  EXPECT_EQ(13U, d.findLockContext(&dtls, l3));
+  d.onUnlock(&dtls, l0);
+  EXPECT_EQ(0U, d.findLockContext(&dtls, l0));
+  EXPECT_EQ(11U, d.findLockContext(&dtls, l1));
+  EXPECT_EQ(12U, d.findLockContext(&dtls, l2));
+  EXPECT_EQ(13U, d.findLockContext(&dtls, l3));
+  d.onUnlock(&dtls, l2);
+  EXPECT_EQ(0U, d.findLockContext(&dtls, l0));
+  EXPECT_EQ(11U, d.findLockContext(&dtls, l1));
+  EXPECT_EQ(0U, d.findLockContext(&dtls, l2));
+  EXPECT_EQ(13U, d.findLockContext(&dtls, l3));
+
+  EXPECT_FALSE(d.onLock(&dtls, l4, 14));
+  EXPECT_EQ(14U, d.findLockContext(&dtls, l4));
+}
+
+TEST(DeadlockDetector, LockContextTest) {
+  RunLockContextTest<BV2>();
+}