Add support for suppressing corner cases of recursive locking that TSAN
normally doesn't allow.

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector1.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector1.cpp
index ccb7065b07ae..58cfc5e1a1fb 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector1.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector1.cpp
@@ -15,6 +15,7 @@
 #include "sanitizer_allocator_internal.h"
 #include "sanitizer_placement_new.h"
 #include "sanitizer_mutex.h"
+#include "sanitizer_stackdepot.h"
 
 #if SANITIZER_DEADLOCK_DETECTOR_VERSION == 1
 
@@ -162,8 +163,19 @@ void DD::MutexAfterLock(DDCallback *cb, DDMutex *m, bool wlock, bool trylock) {
 
   SpinMutexLock lk(&mtx);
   MutexEnsureID(lt, m);
-  if (wlock)  // Only a recursive rlock may be held.
-    CHECK(!dd.isHeld(&lt->dd, m->id));
+  // Only a recursive rlock may be held.
+  if (wlock && dd.isHeld(&lt->dd, m->id)) {
+    // Get stack traces from where the lock is already held.
+    u32 held_stk = dd.findLockContext(&lt->dd, m->id);
+    if (!cb->IsDeadlockSuppressed(held_stk)) {
+      stk = stk ? stk : cb->Unwind();
+      if (!cb->IsDeadlockSuppressed(stk)) {
+        // We could avoid calling this twice, by storing the result above, but
+        // we do want the error message to be unchanged.
+        CHECK(!dd.isHeld(&lt->dd, m->id));
+      }
+    }
+  }
   if (!trylock)
     dd.addEdges(&lt->dd, m->id, stk ? stk : cb->Unwind(), cb->UniqueTid());
   dd.onLockAfter(&lt->dd, m->id, stk);
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector_interface.h b/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector_interface.h
index 7f461c98bade..252e62e05622 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector_interface.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector_interface.h
@@ -66,6 +66,7 @@ struct DDCallback {
 
   virtual u32 Unwind() { return 0; }
   virtual int UniqueTid() { return 0; }
+  virtual bool IsDeadlockSuppressed(u32 stk) { return false; }
 
  protected:
   ~DDCallback() {}
diff --git a/compiler-rt/lib/tsan/rtl/tsan_rtl_mutex.cpp b/compiler-rt/lib/tsan/rtl/tsan_rtl_mutex.cpp
index 30f5e964939d..2b254e323330 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_rtl_mutex.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_rtl_mutex.cpp
@@ -15,9 +15,11 @@
 #include <sanitizer_common/sanitizer_stackdepot.h>
 
 #include "tsan_flags.h"
+#include "tsan_mman.h"
 #include "tsan_platform.h"
 #include "tsan_report.h"
 #include "tsan_rtl.h"
+#include "tsan_suppressions.h"
 #include "tsan_symbolize.h"
 #include "tsan_sync.h"
 
@@ -40,6 +42,21 @@ struct Callback final : public DDCallback {
 
   StackID Unwind() override { return CurrentStackId(thr, pc); }
   int UniqueTid() override { return thr->tid; }
+
+  bool IsDeadlockSuppressed(u32 stk) override {
+    bool result = false;
+    if (stk) {
+      Suppression *supp = nullptr;
+      ReportStack *rs = SymbolizeStackId(stk);
+      rs->suppressable = true;
+      result = IsSuppressed(ReportTypeDeadlock, rs, &supp);
+      if (rs->frames) {
+        rs->frames->ClearAll();
+      }
+      DestroyAndFree(rs);
+    }
+    return result;
+  }
 };
 
 void DDMutexInit(ThreadState *thr, uptr pc, SyncVar *s) {