| Summary: | ASTERISK-11521: Deadlock if feature in use while reload attempted | ||
| Reporter: | Chase Venters (chaseventers) | Labels: | |
| Date Opened: | 2008-02-26 19:29:45.000-0600 | Date Closed: | 2008-02-27 11:08:33.000-0600 |
| Priority: | Critical | Regression? | No |
| Status: | Closed/Complete | Components: | Resources/res_features |
| Versions: | Frequency of Occurrence | ||
| Related Issues: | |||
| Environment: | Attachments: | ( 0) reload-deadlock.txt | |
| Description: | We encountered a deadlock today with Asterisk 1.4.18. I gave Asterisk SIGSEGV so that I could get a crash dump to see what is going on. (We don't build with DEBUG_THREADS right now because we had a crash bug in that code some months prior). The deadlock appears to be this: in thread 10327, ast_module_reload() grabs the module_list lock and then nests into the reload() callback for a module. The res_features.c reload() function calls load_config(), which calls unmap_features() which attempts to acquire features_lock. Meanwhile, another thread (10314 in my dump) has features_lock read-locked inside of ast_feature_interpret(). That calls builtin_blindtransfer() through the .operation function pointer, which is calling finishup, and eventually finds its way to ast_update_use_count(), which wants the module_list lock. So the "reload" thread 10327 has module_list and wants features_lock. 10314 has features_lock but wants module_list. A deadlock results. | ||
| Comments: | By: Digium Subversion (svnbot) 2008-02-27 11:03:56.000-0600 Repository: asterisk Revision: 104596 U branches/1.4/main/loader.c ------------------------------------------------------------------------ r104596 | file | 2008-02-27 11:03:55 -0600 (Wed, 27 Feb 2008) | 4 lines Use the lock (which already existed, it just wasn't used) on the updaters list to protect the contents instead of the overall module list lock. (closes issue ASTERISK-11521) Reported by: ChaseVenters ------------------------------------------------------------------------ http://svn.digium.com/view/asterisk?view=rev&revision=104596 By: Digium Subversion (svnbot) 2008-02-27 11:08:33.000-0600 Repository: asterisk Revision: 104597 _U trunk/ U trunk/main/loader.c ------------------------------------------------------------------------ r104597 | file | 2008-02-27 11:08:31 -0600 (Wed, 27 Feb 2008) | 12 lines Merged revisions 104596 via svnmerge from https://origsvn.digium.com/svn/asterisk/branches/1.4 ........ r104596 | file | 2008-02-27 13:07:33 -0400 (Wed, 27 Feb 2008) | 4 lines Use the lock (which already existed, it just wasn't used) on the updaters list to protect the contents instead of the overall module list lock. (closes issue ASTERISK-11521) Reported by: ChaseVenters ........ ------------------------------------------------------------------------ http://svn.digium.com/view/asterisk?view=rev&revision=104597 | ||