Bug 217773

Summary: v2: WebKit::XPCServiceEventHandler block should call exit() on the main thread
Product: WebKit Reporter: David Kilzer (:ddkilzer) <ddkilzer>
Component: WebKit2Assignee: David Kilzer (:ddkilzer) <ddkilzer>
Status: RESOLVED FIXED    
Severity: Normal CC: cdumez, ggaren, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: Other   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on: 216594    
Bug Blocks:    
Attachments:
Description Flags
Patch v1 ggaren: review+, ddkilzer: commit-queue-

David Kilzer (:ddkilzer)
Reported 2020-10-15 11:42:30 PDT
WebKit::XPCServiceEventHandler block should call exit() on the main thread. The fix in Bug 216594 / r267206 didn't work because apparently libdispatch thought the main thread was the current thread (maybe since this happened during exit(): Thread 0:: Dispatch queue: com.apple.main-thread 0 libSC.dylib 0x00007fff5df818f5 void std::__1::__tree_remove<std::__1::__tree_node_base<void*>*>(std::__1::__tree_node_base<void*>*, std::__1::__tree_node_base<void*>*) + 565 1 libSC.dylib 0x00007fff5df81296 boost::serialization::typeid_system::extended_type_info_typeid_0::type_unregister() + 598 2 libSC.dylib 0x00007fff5e116a1f boost::serialization::detail::singleton_wrapper<boost::serialization::extended_type_info_typeid<_SC_CI_TRANSFORM_SHADER_DESC> >::~singleton_wrapper() + 47 3 libsystem_c.dylib 0x00007fff20324ca7 __cxa_finalize_ranges + 316 4 libsystem_c.dylib 0x00007fff20324f92 exit + 53 5 com.apple.WebKit 0x00007fff3c627bcc invocation function for block in WebKit::AuxiliaryProcess::stopNSRunLoop() + 11 6 com.apple.CoreFoundation 0x00007fff204f05a2 __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12 7 com.apple.CoreFoundation 0x00007fff204f044c __CFRunLoopDoBlocks + 437 8 com.apple.CoreFoundation 0x00007fff204ef132 __CFRunLoopRun + 907 9 com.apple.CoreFoundation 0x00007fff204ee6ce CFRunLoopRunSpecific + 563 10 com.apple.Foundation 0x00007fff212786d1 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 212 11 com.apple.Foundation 0x00007fff21306ab4 -[NSRunLoop(NSRunLoop) run] + 76 12 libxpc.dylib 0x00007fff201473dd _xpc_objc_main + 825 13 libxpc.dylib 0x00007fff20146e65 xpc_main + 437 14 com.apple.WebKit 0x00007fff3c5dc3d2 WebKit::XPCServiceMain(int, char const**) + 629 15 libdyld.dylib 0x00007fff20413591 start + 1 [...] Thread 3 Crashed:: Dispatch queue: com.apple.root.default-qos 0 libSC.dylib 0x00007fff5df80e65 boost::serialization::typeid_system::extended_type_info_typeid_0::is_less_than(boost::serialization::extended_type_info const&) const + 21 1 libSC.dylib 0x00007fff5df810dc boost::serialization::typeid_system::extended_type_info_typeid_0::type_unregister() + 156 2 libSC.dylib 0x00007fff5e1165bf boost::serialization::detail::singleton_wrapper<boost::serialization::extended_type_info_typeid<_SC_PRIMSHADER_VPORT_CONTROLS_LUT> >::~singleton_wrapper() + 47 3 libsystem_c.dylib 0x00007fff20324ca7 __cxa_finalize_ranges + 316 4 libsystem_c.dylib 0x00007fff20324f92 exit + 53 5 com.apple.WebKit 0x00007fff3c5dd755 invocation function for block in WebKit::XPCServiceEventHandler(NSObject<OS_xpc_object>*) + 616 6 libxpc.dylib 0x00007fff2013ec28 _xpc_connection_call_event_handler + 56 7 libxpc.dylib 0x00007fff2013d90c _xpc_connection_mach_event + 535 8 libdispatch.dylib 0x00007fff2024c867 _dispatch_client_callout4 + 9 9 libdispatch.dylib 0x00007fff20266ec0 _dispatch_mach_cancel_invoke + 65 10 libdispatch.dylib 0x00007fff202647f4 _dispatch_mach_invoke + 1070 11 libdispatch.dylib 0x00007fff2025cc5d _dispatch_workloop_worker_thread + 819 12 libsystem_pthread.dylib 0x00007fff203f4499 _pthread_wqthread + 314 13 libsystem_pthread.dylib 0x00007fff203f3467 start_wqthread + 15
Attachments
Patch v1 (2.80 KB, patch)
2020-10-15 12:00 PDT, David Kilzer (:ddkilzer) 		ggaren: review+
ddkilzer: commit-queue-
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
David Kilzer (:ddkilzer)
Comment 1 2020-10-15 11:46:08 PDT
<rdar://problem/70275659>
David Kilzer (:ddkilzer)
Comment 2 2020-10-15 12:00:55 PDT
Created attachment 411471 [details] Patch v1
Geoffrey Garen
Comment 3 2020-10-15 16:27:38 PDT
Yes, during exit libdispatch somewhat randomly picks a new thread to be the "main queue" thread. I have seen many cases where this behavior confused someone and no cases where it helped someone. Oh well. To clarify, it's not that the *current* thread became the main queue thread; that would have caused a deadlock. Instead, some *other* thread became the main queue thread, and we called exit() on that thread.
Geoffrey Garen
Comment 4 2020-10-15 16:31:38 PDT
Comment on attachment 411471 [details] Patch v1 r=me
David Kilzer (:ddkilzer)
Comment 5 2020-10-15 18:45:34 PDT
Committed r268570: <https://trac.webkit.org/changeset/268570>
David Kilzer (:ddkilzer)
Comment 6 2020-10-15 18:54:46 PDT
(In reply to David Kilzer (:ddkilzer) from comment #5) > Committed r268570: <https://trac.webkit.org/changeset/268570> Just modified the commit log message to reflect Geoff's comments in Comment #3.
Note You need to log in before you can comment on or make changes to this bug.