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
llvm-svn: 357276
diff --git a/lldb/include/lldb/Core/ModuleSpec.h b/lldb/include/lldb/Core/ModuleSpec.h
index 16a8cfa..ab0f4e9 100644
--- a/lldb/include/lldb/Core/ModuleSpec.h
+++ b/lldb/include/lldb/Core/ModuleSpec.h
@@ -311,8 +311,10 @@
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;
diff --git a/lldb/include/lldb/Utility/StreamTee.h b/lldb/include/lldb/Utility/StreamTee.h
index 43e99ac..92e94d4 100644
--- a/lldb/include/lldb/Utility/StreamTee.h
+++ b/lldb/include/lldb/Utility/StreamTee.h
@@ -49,8 +49,11 @@
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;
diff --git a/lldb/source/Breakpoint/BreakpointLocationCollection.cpp b/lldb/source/Breakpoint/BreakpointLocationCollection.cpp
index 413c12a..0651ca0 100644
--- a/lldb/source/Breakpoint/BreakpointLocationCollection.cpp
+++ b/lldb/source/Breakpoint/BreakpointLocationCollection.cpp
@@ -181,17 +181,11 @@
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;
}
diff --git a/lldb/source/Core/ModuleList.cpp b/lldb/source/Core/ModuleList.cpp
index 8740bd0..d59e429 100644
--- a/lldb/source/Core/ModuleList.cpp
+++ b/lldb/source/Core/ModuleList.cpp
@@ -130,25 +130,12 @@
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;
}
diff --git a/lldb/source/Target/SectionLoadList.cpp b/lldb/source/Target/SectionLoadList.cpp
index 45b6b52..598f49c 100644
--- a/lldb/source/Target/SectionLoadList.cpp
+++ b/lldb/source/Target/SectionLoadList.cpp
@@ -27,8 +27,9 @@
}
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;
}
diff --git a/lldb/source/Target/ThreadList.cpp b/lldb/source/Target/ThreadList.cpp
index 86248da..afdfda3 100644
--- a/lldb/source/Target/ThreadList.cpp
+++ b/lldb/source/Target/ThreadList.cpp
@@ -37,8 +37,10 @@
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;
