Merge #16033: Hold cs_main when reading chainActive via getTipLocator(). Remove assumeLocked().

9402ef0739 Remove temporary method assumeLocked(). Remove LockingStateImpl. Remove redundant cs_main locks. (practicalswift)
593a8e8a2c wallet: Use chain.lock() instead of temporary chain.assumeLocked() (practicalswift)

Pull request description:

  Fixes #16028.

  Problem description:

  `LockAnnotation lock(::cs_main)` is a guarantee to the compiler thread analysis that `::cs_main` is locked (when it couldn't be determined otherwise).

  Despite being annotated with the locking guarantee ...

  https://github.com/bitcoin/bitcoin/blob/65526fc8666fef35ef908dbc225f706bef642c7e/src/interfaces/chain.cpp#L134-L138

  ... `getTipLocator()` reads `chainActive` (via `::ChainActive()`) without holding `cs_main`.

  This can be verified by adding the following `AssertLockHeld(cs_main)`:

  ```
  $ git diff
  diff --git a/src/interfaces/chain.cpp b/src/interfaces/chain.cpp
  index 59623284d..9fc693a0f 100644
  --- a/src/interfaces/chain.cpp
  +++ b/src/interfaces/chain.cpp
  @@ -134,6 +134,7 @@ class LockImpl : public Chain::Lock
       CBlockLocator getTipLocator() override
       {
           LockAnnotation lock(::cs_main);
  +        AssertLockHeld(::cs_main);
           return ::ChainActive().GetLocator();
       }
       Optional<int> findLocatorFork(const CBlockLocator& locator) override
  $ make check
  ../build-aux/test-driver: line 107: 12881 Aborted                 "$@" > $log_file 2>&1
  FAIL: qt/test/test_bitcoin-qt
  ```

ACKs for commit 9402ef:
  MarcoFalke:
    utACK 9402ef0739fdcd8e989c07c0595095e9608b243c
  ryanofsky:
    utACK 9402ef0739fdcd8e989c07c0595095e9608b243c. Changes are consolidating commits and removing redundant lock2 cs_main calls

Tree-SHA512: 0a030bf0c07eb53194ecc246f973ef389dd42a0979f51932bf94bdf7e90c52473ae03be49718ee1629582b05dd8e0dc020b5a210318c93378ea4ace90c0f9f72

2 files changed, 3 insertions, 12 deletions

diff --git a/src/interfaces/chain.cpp b/src/interfaces/chain.cpp
index d2a915ec02..6097d80931 100644
--- a/src/interfaces/chain.cpp
+++ b/src/interfaces/chain.cpp
@@ -37,7 +37,7 @@
 namespace interfaces {
 namespace {
 
-class LockImpl : public Chain::Lock
+class LockImpl : public Chain::Lock, public UniqueLock<CCriticalSection>
 {
     Optional<int> getHeight() override
     {
@@ -155,10 +155,7 @@ class LockImpl : public Chain::Lock
         return AcceptToMemoryPool(::mempool, state, tx, nullptr /* missing inputs */, nullptr /* txn replaced */,
             false /* bypass limits */, absurd_fee);
     }
-};
 
-class LockingStateImpl : public LockImpl, public UniqueLock<CCriticalSection>
-{
     using UniqueLock::UniqueLock;
 };
 
@@ -249,13 +246,12 @@ class ChainImpl : public Chain
 public:
     std::unique_ptr<Chain::Lock> lock(bool try_lock) override
     {
-        auto result = MakeUnique<LockingStateImpl>(::cs_main, "cs_main", __FILE__, __LINE__, try_lock);
+        auto result = MakeUnique<LockImpl>(::cs_main, "cs_main", __FILE__, __LINE__, try_lock);
         if (try_lock && result && !*result) return {};
         // std::move necessary on some compilers due to conversion from
-        // LockingStateImpl to Lock pointer
+        // LockImpl to Lock pointer
         return std::move(result);
     }
-    std::unique_ptr<Chain::Lock> assumeLocked() override { return MakeUnique<LockImpl>(); }
     bool findBlock(const uint256& hash, CBlock* block, int64_t* time, int64_t* time_max) override
     {
         CBlockIndex* index;
diff --git a/src/interfaces/chain.h b/src/interfaces/chain.h
index 1d604bd823..e675defd47 100644
--- a/src/interfaces/chain.h
+++ b/src/interfaces/chain.h
@@ -138,11 +138,6 @@ public:
     //! unlocked when the returned interface is freed.
     virtual std::unique_ptr<Lock> lock(bool try_lock = false) = 0;
 
-    //! Return Lock interface assuming chain is already locked. This
-    //! method is temporary and is only used in a few places to avoid changing
-    //! behavior while code is transitioned to use the Chain::Lock interface.
-    virtual std::unique_ptr<Lock> assumeLocked() = 0;
-
     //! Return whether node has the block and optionally return block metadata
     //! or contents.
     //!