From: Jason Dillaman <dillaman@redhat.com>
Date: Fri, 9 Sep 2016 14:42:50 +0000 (-0400)
Subject: librbd: possible deadlock if cluster connection closed after image
X-Git-Tag: v10.2.4~28^2~1
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=1ca4dc6d1bd6aebece500c6e91f6a9871af0e1f1;p=ceph.git

librbd: possible deadlock if cluster connection closed after image

Fixes: http://tracker.ceph.com/issues/17254
Signed-off-by: Jason Dillaman <dillaman@redhat.com>
(cherry picked from commit 818c2f2abc972f689acb7d783c2a684bcc9e6e51)
---

diff --git a/src/librbd/ImageWatcher.cc b/src/librbd/ImageWatcher.cc
index 7aeb1c93489..c828163b8ad 100644
--- a/src/librbd/ImageWatcher.cc
+++ b/src/librbd/ImageWatcher.cc
@@ -54,13 +54,19 @@ struct C_UnwatchAndFlush : public Context {
       r = rados.aio_watch_flush(aio_comp);
       assert(r == 0);
       aio_comp->release();
-    } else {
-      Context::complete(ret_val);
+      return;
     }
+
+    // ensure our reference to the RadosClient is released prior
+    // to completing the callback to avoid racing an explicit
+    // librados shutdown
+    Context *ctx = on_finish;
+    delete this;
+
+    ctx->complete(ret_val);
   }
 
   virtual void finish(int r) override {
-    on_finish->complete(r);
   }
 };