git commit: TS-2191 we should not simply reschdule the http_sm if the sm_list`s mutex is not acquired, because the client_vc`s timeout events maybe triggered. The race may lead http_sm received a event after it is deleted. Sub task (TS-2192)

[we...@apache.org]

Updated Branches:
  refs/heads/master e8672a893 -> a27b9e73a


TS-2191 we should not simply reschdule the http_sm if the sm_list`s mutex
is not acquired, because the client_vc`s timeout events maybe triggered.
The race may lead http_sm received a event after it is deleted.
Sub task (TS-2192)


Project: http://git-wip-us.apache.org/repos/asf/trafficserver/repo
Commit: http://git-wip-us.apache.org/repos/asf/trafficserver/commit/a27b9e73
Tree: http://git-wip-us.apache.org/repos/asf/trafficserver/tree/a27b9e73
Diff: http://git-wip-us.apache.org/repos/asf/trafficserver/diff/a27b9e73

Branch: refs/heads/master
Commit: a27b9e73a5e113a0231d56817e86fbad27583180
Parents: e8672a8
Author: weijin <ta...@taobao.com>
Authored: Mon Sep 9 23:36:34 2013 +0800
Committer: weijin <ta...@taobao.com>
Committed: Mon Sep 9 23:51:29 2013 +0800

----------------------------------------------------------------------
 CHANGES              |  2 ++
 proxy/http/HttpSM.cc | 12 +++++-------
 2 files changed, 7 insertions(+), 7 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/trafficserver/blob/a27b9e73/CHANGES
----------------------------------------------------------------------
diff --git a/CHANGES b/CHANGES
index 1c7d948..878b55b 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,5 +1,7 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache Traffic Server 4.1.0
+  
+  *) [TS-2191] not reschedule http_sm when the sm_list`s lock is not acquired.
 
   *) [TS-1086] Avoid edge case returning 304 to an unconditional request.
      Diagnosis and patch by Mohamad Khateeb.

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/a27b9e73/proxy/http/HttpSM.cc
----------------------------------------------------------------------
diff --git a/proxy/http/HttpSM.cc b/proxy/http/HttpSM.cc
index 3804c50..113a89b 100644
--- a/proxy/http/HttpSM.cc
+++ b/proxy/http/HttpSM.cc
@@ -520,13 +520,11 @@ HttpSM::state_add_to_list(int event, void * /* data ATS_UNUSED */)
     int bucket = ((unsigned int) sm_id % HTTP_LIST_BUCKETS);
 
     MUTEX_TRY_LOCK(lock, HttpSMList[bucket].mutex, mutex->thread_holding);
-    if (!lock) {
-      HTTP_SM_SET_DEFAULT_HANDLER(&HttpSM::state_add_to_list);
-      mutex->thread_holding->schedule_in(this, HTTP_LIST_RETRY);
-      return EVENT_DONE;
-    }
-
-    HttpSMList[bucket].sm_list.push(this);
+    // the client_vc`s timeout events can be triggered, so we should not
+    // reschedule the http_sm when the lock is not acquired.
+    // FIXME: the sm_list may miss some http_sms when the lock contention
+    if (lock)
+      HttpSMList[bucket].sm_list.push(this);
   }
 
   t_state.api_next_action = HttpTransact::HTTP_API_SM_START;