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Revert "[fuzzer][Fuchsia] Prevent deadlock from suspending threads" (#155042)

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Reverts llvm/llvm-project#154854 because it broke Clang toolchain
builders for Fuchsia:

https://luci-milo.appspot.com/ui/p/fuchsia/builders/toolchain.ci/clang-linux-x64/b8705803649235662417/overview
This commit is contained in:
gulfemsavrun 2025-08-22 15:54:46 -07:00 committed by GitHub
parent 4028896d4b
commit 781a4db6b5
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GPG Key ID: B5690EEEBB952194
2 changed files with 3 additions and 61 deletions
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4
compiler-rt/lib/fuzzer/FuzzerDriver.cpp
View File

@ -306,9 +306,6 @@ static int RunInMultipleProcesses(const std::vector<std::string> &Args,
return HasErrors ? 1 : 0;
}
// Fuchsia needs to do some book checking before starting the RssThread,
// so it has its own implementation.
#if !LIBFUZZER_FUCHSIA
static void RssThread(Fuzzer *F, size_t RssLimitMb) {
while (true) {
SleepSeconds(1);
@ -324,7 +321,6 @@ static void StartRssThread(Fuzzer *F, size_t RssLimitMb) {
std::thread T(RssThread, F, RssLimitMb);
T.detach();
}
#endif
int RunOneTest(Fuzzer *F, const char *InputFilePath, size_t MaxLen) {
Unit U = FileToVector(InputFilePath);

60
compiler-rt/lib/fuzzer/FuzzerUtilFuchsia.cpp
View File

@ -68,9 +68,6 @@ void ExitOnErr(zx_status_t Status, const char *Syscall) {
}
void AlarmHandler(int Seconds) {
// Signal the alarm thread started.
ExitOnErr(_zx_object_signal(SignalHandlerEvent, 0, ZX_USER_SIGNAL_0),
"_zx_object_signal alarm");
while (true) {
SleepSeconds(Seconds);
Fuzzer::StaticAlarmCallback();
@ -285,7 +282,6 @@ void CrashHandler() {
Self, ZX_EXCEPTION_CHANNEL_DEBUGGER, &Channel.Handle),
"_zx_task_create_exception_channel");
// Signal the crash thread started.
ExitOnErr(_zx_object_signal(SignalHandlerEvent, 0, ZX_USER_SIGNAL_0),
"_zx_object_signal");
@ -389,49 +385,10 @@ void StopSignalHandler() {
_zx_handle_close(SignalHandlerEvent);
}
void RssThread(Fuzzer *F, size_t RssLimitMb) {
// Signal the rss thread started.
//
// We must wait for this thread to start because we could accidentally suspend
// it while the crash handler is attempting to handle the
// ZX_EXCP_THREAD_STARTING exception. If the crash handler is suspended by the
// lsan machinery, then there's no way for this thread to indicate it's
// suspended because it's blocked on waiting for the exception to be handled.
ExitOnErr(_zx_object_signal(SignalHandlerEvent, 0, ZX_USER_SIGNAL_0),
"_zx_object_signal rss");
while (true) {
SleepSeconds(1);
size_t Peak = GetPeakRSSMb();
if (Peak > RssLimitMb)
F->RssLimitCallback();
}
}
} // namespace
void StartRssThread(Fuzzer *F, size_t RssLimitMb) {
// Set up the crash handler and wait until it is ready before proceeding.
assert(SignalHandlerEvent == ZX_HANDLE_INVALID);
ExitOnErr(_zx_event_create(0, &SignalHandlerEvent), "_zx_event_create");
if (!RssLimitMb)
return;
std::thread T(RssThread, F, RssLimitMb);
T.detach();
// Wait for the rss thread to start.
ExitOnErr(_zx_object_wait_one(SignalHandlerEvent, ZX_USER_SIGNAL_0,
ZX_TIME_INFINITE, nullptr),
"_zx_object_wait_one rss");
ExitOnErr(_zx_object_signal(SignalHandlerEvent, ZX_USER_SIGNAL_0, 0),
"_zx_object_signal rss clear");
}
// Platform specific functions.
void SetSignalHandler(const FuzzingOptions &Options) {
assert(SignalHandlerEvent != ZX_HANDLE_INVALID &&
"This should've been setup by StartRssThread.");
// Make sure information from libFuzzer and the sanitizers are easy to
// reassemble. `__sanitizer_log_write` has the added benefit of ensuring the
// DSO map is always available for the symbolizer.
@ -447,20 +404,6 @@ void SetSignalHandler(const FuzzingOptions &Options) {
if (Options.HandleAlrm && Options.UnitTimeoutSec > 0) {
std::thread T(AlarmHandler, Options.UnitTimeoutSec / 2 + 1);
T.detach();
// Wait for the alarm thread to start.
//
// We must wait for this thread to start because we could accidentally
// suspend it while the crash handler is attempting to handle the
// ZX_EXCP_THREAD_STARTING exception. If the crash handler is suspended by
// the lsan machinery, then there's no way for this thread to indicate it's
// suspended because it's blocked on waiting for the exception to be
// handled.
ExitOnErr(_zx_object_wait_one(SignalHandlerEvent, ZX_USER_SIGNAL_0,
ZX_TIME_INFINITE, nullptr),
"_zx_object_wait_one alarm");
ExitOnErr(_zx_object_signal(SignalHandlerEvent, ZX_USER_SIGNAL_0, 0),
"_zx_object_signal alarm clear");
}
// Options.HandleInt and Options.HandleTerm are not supported on Fuchsia
@ -470,6 +413,9 @@ void SetSignalHandler(const FuzzingOptions &Options) {
!Options.HandleFpe && !Options.HandleAbrt && !Options.HandleTrap)
return;
// Set up the crash handler and wait until it is ready before proceeding.
ExitOnErr(_zx_event_create(0, &SignalHandlerEvent), "_zx_event_create");
SignalHandler = std::thread(CrashHandler);
zx_status_t Status = _zx_object_wait_one(SignalHandlerEvent, ZX_USER_SIGNAL_0,
ZX_TIME_INFINITE, nullptr);