Changes imported from Abseil "staging" branch:

  - fbff677ef850865ea67ed6771a8ed348be181e8e Modify sysinfo.cc to support GetTID on Akaros. by Abseil Team <absl-team@google.com>
  - f1c2929e08a3d4181e08cb5014c4a569306fd922 Two functions that did not refer to their arguments unles... by Abseil Team <absl-team@google.com>
  - ee43cc3bfdb4d84d40eee31fb25ecdc1aa060f47 Support Akaros (https://akaros.org) in the ABSL spinlock_... by Abseil Team <absl-team@google.com>
  - 6869c8c5253126459d6c7f0aa708d8612c8e5963 Make sure vdso_base_ is constant-intialized. by Abseil Team <absl-team@google.com>
  - d54e0366efc8d44cd5da5fd157734da966dc45e8 Add missing include for assert used by ABSL_ASSERT. by Derek Mauro <dmauro@google.com>
  - a5139775f3917bb5201e7fc838135766daa05b8d When building against GLIBC-2.16 or newer, use getauxval(... by Abseil Team <absl-team@google.com>

GitOrigin-RevId: fbff677ef850865ea67ed6771a8ed348be181e8e
Change-Id: Ie3549f6ef054783dd104304d2faf8d9800c16b83

1 files changed, 35 insertions, 0 deletions

diff --git a/absl/base/internal/spinlock_akaros.inc b/absl/base/internal/spinlock_akaros.inc
new file mode 100644
index 000000000000..051c8cf87fb6
--- /dev/null
+++ b/absl/base/internal/spinlock_akaros.inc
@@ -0,0 +1,35 @@
+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// This file is an Akaros-specific part of spinlock_wait.cc
+
+#include <atomic>
+
+#include "absl/base/internal/scheduling_mode.h"
+
+extern "C" {
+
+ABSL_ATTRIBUTE_WEAK void AbslInternalSpinLockDelay(
+    std::atomic<uint32_t>* /* lock_word */, uint32_t /* value */,
+    int /* loop */, absl::base_internal::SchedulingMode /* mode */) {
+  // In Akaros, one must take care not to call anything that could cause a
+  // malloc(), a blocking system call, or a uthread_yield() while holding a
+  // spinlock. Our callers assume will not call into libraries or other
+  // arbitrary code.
+}
+
+ABSL_ATTRIBUTE_WEAK void AbslInternalSpinLockWake(
+    std::atomic<uint32_t>* /* lock_word */, bool /* all */) {}
+
+}  // extern "C"