[DISPATCH-2129] shutdown race accessing core->running flag

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 1.16.0
• Fix Version/s: Backlog
• Component/s: Router Node
• Labels: race-condition tsan
• Assignee: Michael Goulish
• Reporter: Ken Giusti
• Created: 18/May/21 15:57
• Updated: 20/Jan/22 13:50

Description

Low priority, but nice to clean up so we can remove the suppression for qdr_core_free.

The core->running flag is set false by the main thread during shutdown.  The flag is checked by the core thread as an indication that the core thread should exit its main loop.

A non-racy approach would be to instead have the main thread queue an action to the core thread to cause it to exit the main loop (by setting the core->running flag to false).

65: WARNING: ThreadSanitizer: data race (pid=613021) 
65: Write of size 1 at 0x7b6400035220 by main thread: 
65: #0 qdr_core_free /home/kgiusti/work/dispatch/qpid-dispatch/src/router_core/router_core.c:140 (libqpid-dispatch.so+0xf0484) 
65: #1 qd_router_free /home/kgiusti/work/dispatch/qpid-dispatch/src/router_node.c:2160 (libqpid-dispatch.so+0x12870e) 
65: #2 qd_dispatch_free /home/kgiusti/work/dispatch/qpid-dispatch/src/dispatch.c:375 (libqpid-dispatch.so+0x81dfd) 
65: #3 main_process /home/kgiusti/work/dispatch/qpid-dispatch/router/src/main.c:119 (qdrouterd+0x402750) 
65: #4 main /home/kgiusti/work/dispatch/qpid-dispatch/router/src/main.c:369 (qdrouterd+0x403557) 
65: 
65: Previous read of size 1 at 0x7b6400035220 by thread T1: 
65: #0 router_core_thread /home/kgiusti/work/dispatch/qpid-dispatch/src/router_core/router_core_thread.c:210 (libqpid-dispatch.so+0xfb416) 
65: #1 _thread_init /home/kgiusti/work/dispatch/qpid-dispatch/src/posix/threading.c:172 (libqpid-dispatch.so+0xad37a) 
65: #2 <null> <null> (libtsan.so.0+0x2d33f)

Issue Links

• is a child of: DISPATCH-2249 Refactor router shutdown to eliminate leaks and races
• relates to: DISPATCH-2109 Shutdown crash: member access within null pointer of type 'struct qdr_node_t'