init: wake genesis wait after ImportBlocks() returns
What the developer wrote
Authored by ismaelsadeeq
init: wake genesis wait after ImportBlocks() returns
If shutdown interrupts ImportBlocks() before genesis activation,
no blockTip notification is sent. The wait predicate allows
shutdown to occur, but the condition variable is never
notified, so init can remain stuck waiting for genesis activation.
Notify the tip condition variable after ImportBlocks() returns so
interrupted imports wake the wait and let it observe the shutdown request.
Add test coverage for interrupting startup after reindex block files import
begins, which exercises the path where ImportBlocks() can return before genesis
activation.
What changed, and why it matters
This commit fixes a bug where Bitcoin Core could hang during shutdown if the user started a 'reindex' and then asked the program to quit before it finished loading the very first block. The fix adds a notification so the shutdown request is noticed, plus a test that simulates this exact scenario. It is a reliability/availability fix, not a security vulnerability that an attacker can exploit.
No immediate security action required. Treat as a normal bug-fix/availability improvement. Users running reindex should upgrade to avoid rare shutdown hangs, but there is no remote exploit.
Security signals we found
Denial-of-service/availability issue: graceful shutdown can hang
Fix is in initialization/shutdown synchronization logic
No attacker-controlled input path identified
Test added to prevent regression of shutdown hang
Evidence from the diff
During initialization, AppInitMain spawns a background ‘initload’ thread that runs ImportBlocks() and ActivateBestChain(). The main init thread can wait on kernel_notifications.m_tip_block_cv for genesis activation. If shutdown is requested while ImportBlocks() is still running and before genesis has been activated, ImportBlocks() returns early without ever sending a blockTip notification, so the condition variable is never signaled and the init thread remains blocked. The patch notifies m_tip_block_cv after ImportBlocks() returns, allowing the wait predicate to observe the shutdown flag. A functional test is added that starts a node with -reindex and terminates it after the ‘Reindexing block file blk00000.dat’ log line, exercising the interrupted-import-before-genesis path.
Changed components
src/init.cpp: AppInitMain background init thread and genesis wait synchronizationtest/functional/feature_init.py: startup/shutdown functional testsInspect captured patch +14 / −3
diff --git a/src/init.cpp b/src/init.cpp
index 0e72443c..290f0936 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -2045,10 +2045,16 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
}
/// \anchor initload
- node.background_init_thread = std::thread(&util::TraceThread, "initload", [=, &chainman, &args, &node] {
+ node.background_init_thread = std::thread(&util::TraceThread, "initload", [=, &chainman, &args, &kernel_notifications, &node] {
ScheduleBatchPriority();
// Import blocks and ActivateBestChain()
ImportBlocks(chainman, vImportFiles);
+ // An interrupted import may return without activating genesis. Wake
+ // the init thread's genesis wait, which is otherwise only notified
+ // on blockTip, and that never fires when the import was interrupted
+ // before activating genesis. This wakeup lets the wait observe the
+ // shutdown request.
+ WITH_LOCK(kernel_notifications.m_tip_block_mutex, kernel_notifications.m_tip_block_cv.notify_all());
WITH_LOCK(::cs_main, chainman.UpdateIBDStatus());
if (args.GetBoolArg("-stopafterblockimport", DEFAULT_STOPAFTERBLOCKIMPORT)) {
LogInfo("Stopping after block import");
diff --git a/test/functional/feature_init.py b/test/functional/feature_init.py
index ad20e39c..18faba33 100755
--- a/test/functional/feature_init.py
+++ b/test/functional/feature_init.py
@@ -63,6 +63,7 @@ class InitTest(BitcoinTestFramework):
node.process.terminate()
assert_equal(0, node.process.wait())
+ reindex_log_line = b'Reindexing block file blk00000.dat'
lines_to_terminate_after = [
b'Validating signatures for all blocks',
b'scheduler thread start',
@@ -87,16 +88,20 @@ class InitTest(BitcoinTestFramework):
]
if self.is_wallet_compiled():
lines_to_terminate_after.append(b'Verifying wallet')
+ lines_to_terminate_after.append(reindex_log_line)
for terminate_line in lines_to_terminate_after:
self.log.info(f"Starting node and will terminate after line {terminate_line}")
with node.busy_wait_for_debug_log([terminate_line]):
+ extra_args = [*ALL_INDEX_ARGS]
+ if terminate_line == reindex_log_line:
+ extra_args += ['-reindex']
if platform.system() == 'Windows':
# CREATE_NEW_PROCESS_GROUP is required in order to be able
# to terminate the child without terminating the test.
- node.start(extra_args=ALL_INDEX_ARGS, creationflags=subprocess.CREATE_NEW_PROCESS_GROUP)
+ node.start(extra_args=extra_args, creationflags=subprocess.CREATE_NEW_PROCESS_GROUP)
else:
- node.start(extra_args=ALL_INDEX_ARGS)
+ node.start(extra_args=extra_args)
self.log.debug("Terminating node after terminate line was found")
sigterm_node()
Why this scored 30/100
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