Author: jingham Date: Fri Mar 29 10:07:30 2019 New Revision: 357276 URL: http://llvm.org/viewvc/llvm-project?rev=357276&view=rev Log: Use the multi-lockable form of std::lock for operator=
For = operators for lists that have mutexes, we were either just taking the locks sequentially or hand-rolling a trick to try to avoid lock inversion. Use the std::lock mechanism for this instead. Differential Revision: https://reviews.llvm.org/D59957 Modified: lldb/trunk/include/lldb/Core/ModuleSpec.h lldb/trunk/include/lldb/Utility/StreamTee.h lldb/trunk/source/Breakpoint/BreakpointLocationCollection.cpp lldb/trunk/source/Core/ModuleList.cpp lldb/trunk/source/Target/SectionLoadList.cpp lldb/trunk/source/Target/ThreadList.cpp Modified: lldb/trunk/include/lldb/Core/ModuleSpec.h URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Core/ModuleSpec.h?rev=357276&r1=357275&r2=357276&view=diff ============================================================================== --- lldb/trunk/include/lldb/Core/ModuleSpec.h (original) +++ lldb/trunk/include/lldb/Core/ModuleSpec.h Fri Mar 29 10:07:30 2019 @@ -311,8 +311,10 @@ public: ModuleSpecList &operator=(const ModuleSpecList &rhs) { if (this != &rhs) { - std::lock_guard<std::recursive_mutex> lhs_guard(m_mutex); - std::lock_guard<std::recursive_mutex> rhs_guard(rhs.m_mutex); + std::lock(m_mutex, rhs.m_mutex); + std::lock_guard<std::recursive_mutex> lhs_guard(m_mutex, std::adopt_lock); + std::lock_guard<std::recursive_mutex> rhs_guard(rhs.m_mutex, + std::adopt_lock); m_specs = rhs.m_specs; } return *this; Modified: lldb/trunk/include/lldb/Utility/StreamTee.h URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/include/lldb/Utility/StreamTee.h?rev=357276&r1=357275&r2=357276&view=diff ============================================================================== --- lldb/trunk/include/lldb/Utility/StreamTee.h (original) +++ lldb/trunk/include/lldb/Utility/StreamTee.h Fri Mar 29 10:07:30 2019 @@ -49,8 +49,11 @@ public: StreamTee &operator=(const StreamTee &rhs) { if (this != &rhs) { Stream::operator=(rhs); - std::lock_guard<std::recursive_mutex> lhs_locker(m_streams_mutex); - std::lock_guard<std::recursive_mutex> rhs_locker(rhs.m_streams_mutex); + std::lock(m_streams_mutex, rhs.m_streams_mutex); + std::lock_guard<std::recursive_mutex> lhs_locker(m_streams_mutex, + std::adopt_lock); + std::lock_guard<std::recursive_mutex> rhs_locker(rhs.m_streams_mutex, + std::adopt_lock); m_streams = rhs.m_streams; } return *this; Modified: lldb/trunk/source/Breakpoint/BreakpointLocationCollection.cpp URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Breakpoint/BreakpointLocationCollection.cpp?rev=357276&r1=357275&r2=357276&view=diff ============================================================================== --- lldb/trunk/source/Breakpoint/BreakpointLocationCollection.cpp (original) +++ lldb/trunk/source/Breakpoint/BreakpointLocationCollection.cpp Fri Mar 29 10:07:30 2019 @@ -181,17 +181,11 @@ void BreakpointLocationCollection::GetDe BreakpointLocationCollection &BreakpointLocationCollection::operator=( const BreakpointLocationCollection &rhs) { - // Same trick as in ModuleList to avoid lock inversion. if (this != &rhs) { - if (uintptr_t(this) > uintptr_t(&rhs)) { - std::lock_guard<std::mutex> lhs_guard(m_collection_mutex); - std::lock_guard<std::mutex> rhs_guard(rhs.m_collection_mutex); + std::lock(m_collection_mutex, rhs.m_collection_mutex); + std::lock_guard<std::mutex> lhs_guard(m_collection_mutex, std::adopt_lock); + std::lock_guard<std::mutex> rhs_guard(rhs.m_collection_mutex, std::adopt_lock); m_break_loc_collection = rhs.m_break_loc_collection; - } else { - std::lock_guard<std::mutex> lhs_guard(m_collection_mutex); - std::lock_guard<std::mutex> rhs_guard(rhs.m_collection_mutex); - m_break_loc_collection = rhs.m_break_loc_collection; - } } return *this; } Modified: lldb/trunk/source/Core/ModuleList.cpp URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Core/ModuleList.cpp?rev=357276&r1=357275&r2=357276&view=diff ============================================================================== --- lldb/trunk/source/Core/ModuleList.cpp (original) +++ lldb/trunk/source/Core/ModuleList.cpp Fri Mar 29 10:07:30 2019 @@ -130,25 +130,12 @@ ModuleList::ModuleList(ModuleList::Notif const ModuleList &ModuleList::operator=(const ModuleList &rhs) { if (this != &rhs) { - // That's probably me nit-picking, but in theoretical situation: - // - // * that two threads A B and - // * two ModuleList's x y do opposite assignments ie.: - // - // in thread A: | in thread B: - // x = y; | y = x; - // - // This establishes correct(same) lock taking order and thus avoids - // priority inversion. - if (uintptr_t(this) > uintptr_t(&rhs)) { - std::lock_guard<std::recursive_mutex> lhs_guard(m_modules_mutex); - std::lock_guard<std::recursive_mutex> rhs_guard(rhs.m_modules_mutex); - m_modules = rhs.m_modules; - } else { - std::lock_guard<std::recursive_mutex> lhs_guard(m_modules_mutex); - std::lock_guard<std::recursive_mutex> rhs_guard(rhs.m_modules_mutex); - m_modules = rhs.m_modules; - } + std::lock(m_modules_mutex, rhs.m_modules_mutex); + std::lock_guard<std::recursive_mutex> lhs_guard(m_modules_mutex, + std::adopt_lock); + std::lock_guard<std::recursive_mutex> rhs_guard(rhs.m_modules_mutex, + std::adopt_lock); + m_modules = rhs.m_modules; } return *this; } Modified: lldb/trunk/source/Target/SectionLoadList.cpp URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Target/SectionLoadList.cpp?rev=357276&r1=357275&r2=357276&view=diff ============================================================================== --- lldb/trunk/source/Target/SectionLoadList.cpp (original) +++ lldb/trunk/source/Target/SectionLoadList.cpp Fri Mar 29 10:07:30 2019 @@ -27,8 +27,9 @@ SectionLoadList::SectionLoadList(const S } void SectionLoadList::operator=(const SectionLoadList &rhs) { - std::lock_guard<std::recursive_mutex> lhs_guard(m_mutex); - std::lock_guard<std::recursive_mutex> rhs_guard(rhs.m_mutex); + std::lock(m_mutex, rhs.m_mutex); + std::lock_guard<std::recursive_mutex> lhs_guard(m_mutex, std::adopt_lock); + std::lock_guard<std::recursive_mutex> rhs_guard(rhs.m_mutex, std::adopt_lock); m_addr_to_sect = rhs.m_addr_to_sect; m_sect_to_addr = rhs.m_sect_to_addr; } Modified: lldb/trunk/source/Target/ThreadList.cpp URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Target/ThreadList.cpp?rev=357276&r1=357275&r2=357276&view=diff ============================================================================== --- lldb/trunk/source/Target/ThreadList.cpp (original) +++ lldb/trunk/source/Target/ThreadList.cpp Fri Mar 29 10:07:30 2019 @@ -37,8 +37,10 @@ const ThreadList &ThreadList::operator=( if (this != &rhs) { // Lock both mutexes to make sure neither side changes anyone on us while // the assignment occurs - std::lock_guard<std::recursive_mutex> guard(GetMutex()); - std::lock_guard<std::recursive_mutex> rhs_guard(rhs.GetMutex()); + std::lock(GetMutex(), rhs.GetMutex()); + std::lock_guard<std::recursive_mutex> guard(GetMutex(), std::adopt_lock); + std::lock_guard<std::recursive_mutex> rhs_guard(rhs.GetMutex(), + std::adopt_lock); m_process = rhs.m_process; m_stop_id = rhs.m_stop_id; _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
