From: Radoslaw Zarzynski <rzarzyns@redhat.com>
Date: Tue, 13 Nov 2018 23:47:06 +0000 (+0100)
Subject: common: try to skip atomical decrement in buffer::ptr::release().
X-Git-Tag: v14.1.0~172^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=48aaf3cbee045852a382097f19e815638ab20926;p=ceph.git

common: try to skip atomical decrement in buffer::ptr::release().

Signed-off-by: Radoslaw Zarzynski <rzarzyns@redhat.com>
---

diff --git a/src/common/buffer.cc b/src/common/buffer.cc
index f6a33e43b68..45af914f989 100644
--- a/src/common/buffer.cc
+++ b/src/common/buffer.cc
@@ -539,7 +539,8 @@ static ceph::spinlock debug_lock;
   {
     if (_raw) {
       bdout << "ptr " << this << " release " << _raw << bendl;
-      if (--_raw->nref == 0) {
+      const bool last_one = (1 == _raw->nref.load(std::memory_order_acquire));
+      if (likely(last_one) || --_raw->nref == 0) {
         // BE CAREFUL: this is called also for hypercombined ptr_node. After
         // freeing underlying raw, `*this` can become inaccessible as well!
         const auto* delete_raw = _raw;