Fix worker race condition in gemmlowp.android-cts_7.1_r1android-cts-7.1_r9android-cts-7.1_r8android-cts-7.1_r7android-cts-7.1_r6android-cts-7.1_r5android-cts-7.1_r4android-cts-7.1_r3android-cts-7.1_r29android-cts-7.1_r28android-cts-7.1_r27android-cts-7.1_r26android-cts-7.1_r25android-cts-7.1_r24android-cts-7.1_r23android-cts-7.1_r22android-cts-7.1_r21android-cts-7.1_r20android-cts-7.1_r2android-cts-7.1_r19android-cts-7.1_r18android-cts-7.1_r17android-cts-7.1_r16android-cts-7.1_r15android-cts-7.1_r14android-cts-7.1_r13android-cts-7.1_r12android-cts-7.1_r11android-cts-7.1_r10android-cts-7.1_r1android-7.1.2_r9android-7.1.2_r8android-7.1.2_r6android-7.1.2_r5android-7.1.2_r4android-7.1.2_r39android-7.1.2_r38android-7.1.2_r37android-7.1.2_r36android-7.1.2_r33android-7.1.2_r32android-7.1.2_r30android-7.1.2_r3android-7.1.2_r29android-7.1.2_r28android-7.1.2_r27android-7.1.2_r25android-7.1.2_r24android-7.1.2_r23android-7.1.2_r2android-7.1.2_r19android-7.1.2_r18android-7.1.2_r17android-7.1.2_r16android-7.1.2_r15android-7.1.2_r14android-7.1.2_r13android-7.1.2_r12android-7.1.2_r11android-7.1.2_r10android-7.1.2_r1android-7.1.1_r9android-7.1.1_r8android-7.1.1_r7android-7.1.1_r61android-7.1.1_r60android-7.1.1_r6android-7.1.1_r59android-7.1.1_r58android-7.1.1_r57android-7.1.1_r56android-7.1.1_r55android-7.1.1_r54android-7.1.1_r53android-7.1.1_r52android-7.1.1_r51android-7.1.1_r50android-7.1.1_r49android-7.1.1_r48android-7.1.1_r47android-7.1.1_r46android-7.1.1_r45android-7.1.1_r44android-7.1.1_r43android-7.1.1_r42android-7.1.1_r41android-7.1.1_r40android-7.1.1_r4android-7.1.1_r39android-7.1.1_r38android-7.1.1_r35android-7.1.1_r33android-7.1.1_r32android-7.1.1_r31android-7.1.1_r3android-7.1.1_r28android-7.1.1_r27android-7.1.1_r26android-7.1.1_r25android-7.1.1_r24android-7.1.1_r23android-7.1.1_r22android-7.1.1_r21android-7.1.1_r20android-7.1.1_r2android-7.1.1_r17android-7.1.1_r16android-7.1.1_r15android-7.1.1_r14android-7.1.1_r13android-7.1.1_r12android-7.1.1_r11android-7.1.1_r10android-7.1.1_r1android-7.1.0_r7android-7.1.0_r6android-7.1.0_r5android-7.1.0_r4android-7.1.0_r3android-7.1.0_r2android-7.1.0_r1nougat-mr2.3-releasenougat-mr2.2-releasenougat-mr2.1-releasenougat-mr2-security-releasenougat-mr2-releasenougat-mr2-pixel-releasenougat-mr2-devnougat-mr1.8-releasenougat-mr1.7-releasenougat-mr1.6-releasenougat-mr1.5-releasenougat-mr1.4-releasenougat-mr1.3-releasenougat-mr1.2-releasenougat-mr1.1-releasenougat-mr1-volantis-releasenougat-mr1-security-releasenougat-mr1-releasenougat-mr1-flounder-releasenougat-mr1-devnougat-mr1-cts-releasenougat-dr1-release

Bug: 29993722

  - Merge upstream change 67949d5f0f0e00d44709570d87f5ffa43b81e4f1
  - Fix race condition by adding explicit memory barriers

Change-Id: Ie3e72ac3307e6b205d9f473aac3eb19ea43866f8
(cherry picked from commit d2f96f0c9363004d5bd8d042dbc70c1519875d33)

1 files changed, 30 insertions, 0 deletions

diff --git a/internal/multi_thread_gemm.h b/internal/multi_thread_gemm.h
index be33d5f..0aacddb 100644
--- a/internal/multi_thread_gemm.h
+++ b/internal/multi_thread_gemm.h
@@ -66,6 +66,34 @@ inline int Do256NOPs() { return 0; }
 
 #endif  // not GEMMLOWP_ALLOW_INLINE_ASM
 
+inline void WriteBarrier() {
+#ifdef GEMMLOWP_ARM_32
+  MemoryBarrier();
+#elif defined(GEMMLOWP_ARM_64)
+  asm volatile("dmb ishst" ::: "memory");
+#elif defined(GEMMLOWP_X86)
+  asm volatile("sfence" ::: "memory");
+#elif defined(__mips__)
+  MemoryBarrier();
+#else
+#error "Unsupported architecture for WriteBarrier."
+#endif
+}
+
+inline void ReadBarrier() {
+#ifdef GEMMLOWP_ARM_32
+  MemoryBarrier();
+#elif defined(GEMMLOWP_ARM_64)
+  asm volatile("dmb ishld" ::: "memory");
+#elif defined(GEMMLOWP_X86)
+  asm volatile("lfence" ::: "memory");
+#elif defined(__mips__)
+  MemoryBarrier();
+#else
+#error "Unsupported architecture for ReadBarrier."
+#endif
+}
+
 // Waits until *var != initial_value.
 //
 // Returns the new value of *var. The guarantee here is that
@@ -255,6 +283,7 @@ class Worker {
       switch (state_to_act_upon) {
         case State::HasWork:
           // Got work to do! So do it, and then revert to 'Ready' state.
+          ReadBarrier();
           assert(task_);
           task_->Run();
           delete task_;
@@ -280,6 +309,7 @@ class Worker {
     assert(!task_);
     task->local_allocator = &local_allocator_;
     task_ = task;
+    WriteBarrier();
     assert(state_ == State::Ready);
     ChangeState(State::HasWork);
   }