Release 4.2.1

Signed-off-by: Andrei Pangin <1749416+apangin@users.noreply.github.com>
(cherry picked from commit b855e0c2c4)

CHANGELOG.md

@@ -1,6 +1,13 @@
 # Changelog
 
-## [4.2] - Early Access
+## [4.2.1] - Maintenance Release
+
+### Bug fixes
+
+ - #1599: Workaround for the kernel PERF_EVENT_IOC_REFRESH bug
+ - #1596: Do not block any signals during execution of a custom crash handler
+
+## [4.2] - 2025-10-20
 
 ### Features
 

Makefile

@@ -1,4 +1,4 @@
-PROFILER_VERSION ?= 4.2
+PROFILER_VERSION ?= 4.2.1
 
 ifeq ($(COMMIT_TAG),true)
   PROFILER_VERSION := $(PROFILER_VERSION)-$(shell git rev-parse --short=8 HEAD)

README.md

@@ -23,12 +23,12 @@ to learn about more features.
 
 # Download
 
-### Stable release: [4.1](https://github.com/async-profiler/async-profiler/releases/tag/v4.1)
+### Stable release: [4.2](https://github.com/async-profiler/async-profiler/releases/tag/v4.2)
 
-- Linux x64: [async-profiler-4.1-linux-x64.tar.gz](https://github.com/async-profiler/async-profiler/releases/download/v4.1/async-profiler-4.1-linux-x64.tar.gz)
-- Linux arm64: [async-profiler-4.1-linux-arm64.tar.gz](https://github.com/async-profiler/async-profiler/releases/download/v4.1/async-profiler-4.1-linux-arm64.tar.gz)
-- macOS arm64/x64: [async-profiler-4.1-macos.zip](https://github.com/async-profiler/async-profiler/releases/download/v4.1/async-profiler-4.1-macos.zip)
-- Profile converters: [jfr-converter.jar](https://github.com/async-profiler/async-profiler/releases/download/v4.1/jfr-converter.jar)
+- Linux x64: [async-profiler-4.2-linux-x64.tar.gz](https://github.com/async-profiler/async-profiler/releases/download/v4.2/async-profiler-4.2-linux-x64.tar.gz)
+- Linux arm64: [async-profiler-4.2-linux-arm64.tar.gz](https://github.com/async-profiler/async-profiler/releases/download/v4.2/async-profiler-4.2-linux-arm64.tar.gz)
+- macOS arm64/x64: [async-profiler-4.2-macos.zip](https://github.com/async-profiler/async-profiler/releases/download/v4.2/async-profiler-4.2-macos.zip)
+- Profile converters: [jfr-converter.jar](https://github.com/async-profiler/async-profiler/releases/download/v4.2/jfr-converter.jar)
 
 ### Nightly builds
 

docs/ConverterUsage.md

@@ -2,7 +2,7 @@
 
 async-profiler provides `jfrconv` utility to convert between different profile output formats.
 `jfrconv` can be found at the same location as the `asprof` binary. Converter is also available
-as a standalone Java application: [`jfr-converter.jar`](https://github.com/async-profiler/async-profiler/releases/download/v4.1/jfr-converter.jar).
+as a standalone Java application: [`jfr-converter.jar`](https://github.com/async-profiler/async-profiler/releases/download/v4.2/jfr-converter.jar).
 
 ## Supported conversions
 

docs/IntegratingAsyncProfiler.md

@@ -11,7 +11,7 @@ $ java -agentpath:/path/to/libasyncProfiler.so=start,event=cpu,file=profile.html
 
 Agent library is configured through the JVMTI argument interface.
 The format of the arguments string is described
-[in the source code](https://github.com/async-profiler/async-profiler/blob/v4.1/src/arguments.cpp#L45).
+[in the source code](https://github.com/async-profiler/async-profiler/blob/v4.2/src/arguments.cpp#L39).
 `asprof` actually converts command line arguments to that format.
 
 Another important use of attaching async-profiler as an agent is for continuous profiling.

pom-converter.xml

@@ -3,7 +3,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>tools.profiler</groupId>
     <artifactId>jfr-converter</artifactId>
-    <version>4.2</version>
+    <version>4.2.1</version>
     <packaging>jar</packaging>
 
     <name>async-profiler</name>

pom.xml

@@ -3,7 +3,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>tools.profiler</groupId>
     <artifactId>async-profiler</artifactId>
-    <version>4.2</version>
+    <version>4.2.1</version>
     <packaging>jar</packaging>
 
     <name>async-profiler</name>

src/os_linux.cpp

@@ -279,8 +279,9 @@ SigAction OS::replaceCrashHandler(SigAction action) {
     struct sigaction sa;
     sigaction(SIGSEGV, NULL, &sa);
     SigAction old_action = sa.sa_handler == SIG_DFL ? restoreSignalHandler : sa.sa_sigaction;
+    sigemptyset(&sa.sa_mask);
     sa.sa_sigaction = action;
-    sa.sa_flags |= SA_SIGINFO | SA_RESTART;
+    sa.sa_flags |= SA_SIGINFO | SA_RESTART | SA_NODEFER;
     sigaction(SIGSEGV, &sa, NULL);
     return old_action;
 }

src/os_macos.cpp

@@ -247,14 +247,16 @@ SigAction OS::replaceCrashHandler(SigAction action) {
 
     sigaction(SIGBUS, NULL, &sa);
     orig_sigbus_handler = sa.sa_handler == SIG_DFL ? restoreSignalHandler : sa.sa_sigaction;
+    sigemptyset(&sa.sa_mask);
     sa.sa_sigaction = action;
-    sa.sa_flags |= SA_SIGINFO | SA_RESTART;
+    sa.sa_flags |= SA_SIGINFO | SA_RESTART | SA_NODEFER;
     sigaction(SIGBUS, &sa, NULL);
 
     sigaction(SIGSEGV, NULL, &sa);
     orig_sigsegv_handler = sa.sa_handler == SIG_DFL ? restoreSignalHandler : sa.sa_sigaction;
+    sigemptyset(&sa.sa_mask);
     sa.sa_sigaction = action;
-    sa.sa_flags |= SA_SIGINFO | SA_RESTART;
+    sa.sa_flags |= SA_SIGINFO | SA_RESTART| SA_NODEFER;
     sigaction(SIGSEGV, &sa, NULL);
 
     // Return an action that dispatches to one of the original handlers depending on signo,

src/perfEvents.h

@@ -20,6 +20,7 @@ class PerfEvents : public CpuEngine {
     static int _max_events;
     static PerfEvent* _events;
     static PerfEventType* _event_type;
+    static int _ioc_enable;
     static bool _alluser;
     static bool _kernel_stack;
     static bool _record_cpu;

src/perfEvents_linux.cpp

@@ -19,6 +19,7 @@
 #include <sys/resource.h>
 #include <sys/stat.h>
 #include <sys/syscall.h>
+#include <sys/utsname.h>
 #include <linux/perf_event.h>
 #include "arch.h"
 #include "fdtransferClient.h"
@@ -153,6 +154,17 @@ static void adjustFDLimit() {
     }
 }
 
+// Workaround for the kernel bug: PERF_EVENT_IOC_REFRESH can hang
+// the entire system on Linux 6.16.x and 6.17.x.
+// See https://github.com/async-profiler/async-profiler/issues/1578
+static bool hasPerfEventRefreshBug() {
+    static struct utsname u{};
+    if (u.release[0] == 0 && uname(&u) != 0) {
+        return false;
+    }
+    return strncmp(u.release, "6.16.", 5) == 0 || strncmp(u.release, "6.17.", 5) == 0;
+}
+
 struct FunctionWithCounter {
     const char* name;
     int counter_arg;
@@ -532,6 +544,7 @@ class PerfEvent : public SpinLock {
 int PerfEvents::_max_events = 0;
 PerfEvent* PerfEvents::_events = NULL;
 PerfEventType* PerfEvents::_event_type = NULL;
+int PerfEvents::_ioc_enable;
 bool PerfEvents::_alluser;
 bool PerfEvents::_kernel_stack;
 bool PerfEvents::_record_cpu;
@@ -641,7 +654,7 @@ int PerfEvents::createForThread(int tid) {
     if (fcntl(fd, F_SETFL, O_ASYNC) < 0 || fcntl(fd, F_SETSIG, _signal) < 0 || fcntl(fd, F_SETOWN_EX, &ex) < 0) {
         err = errno;
         Log::warn("perf_event fcntl failed: %s", strerror(err));
-    } else if (ioctl(fd, PERF_EVENT_IOC_RESET, 0) < 0 || ioctl(fd, PERF_EVENT_IOC_REFRESH, 1) < 0) {
+    } else if (ioctl(fd, PERF_EVENT_IOC_RESET, 0) < 0 || ioctl(fd, _ioc_enable, 1) < 0) {
         err = errno;
         Log::warn("perf_event ioctl failed: %s", strerror(err));
     } else {
@@ -697,6 +710,10 @@ void PerfEvents::signalHandler(int signo, siginfo_t* siginfo, void* ucontext) {
         return;
     }
 
+    if (_ioc_enable == PERF_EVENT_IOC_ENABLE) {
+        ioctl(siginfo->si_fd, PERF_EVENT_IOC_DISABLE, 0);
+    }
+
     if (_enabled) {
         ExecutionEvent event(TSC::ticks());
         u64 counter = readCounter(siginfo, ucontext);
@@ -706,7 +723,7 @@ void PerfEvents::signalHandler(int signo, siginfo_t* siginfo, void* ucontext) {
     }
 
     ioctl(siginfo->si_fd, PERF_EVENT_IOC_RESET, 0);
-    ioctl(siginfo->si_fd, PERF_EVENT_IOC_REFRESH, 1);
+    ioctl(siginfo->si_fd, _ioc_enable, 1);
 }
 
 void PerfEvents::signalHandlerJ9(int signo, siginfo_t* siginfo, void* ucontext) {
@@ -715,6 +732,10 @@ void PerfEvents::signalHandlerJ9(int signo, siginfo_t* siginfo, void* ucontext)
         return;
     }
 
+    if (_ioc_enable == PERF_EVENT_IOC_ENABLE) {
+        ioctl(siginfo->si_fd, PERF_EVENT_IOC_DISABLE, 0);
+    }
+
     if (_enabled) {
         u64 counter = readCounter(siginfo, ucontext);
         J9StackTraceNotification notif;
@@ -726,7 +747,7 @@ void PerfEvents::signalHandlerJ9(int signo, siginfo_t* siginfo, void* ucontext)
     }
 
     ioctl(siginfo->si_fd, PERF_EVENT_IOC_RESET, 0);
-    ioctl(siginfo->si_fd, PERF_EVENT_IOC_REFRESH, 1);
+    ioctl(siginfo->si_fd, _ioc_enable, 1);
 }
 
 const char* PerfEvents::title() {
@@ -830,6 +851,13 @@ Error PerfEvents::start(Arguments& args) {
         _alluser = strcmp(args._event, EVENT_CPU) != 0 && !supported();
     }
 
+    if (strcmp(_event_type->name, "cpu-clock") == 0 && hasPerfEventRefreshBug()) {
+        Log::debug("Enable workaround for PERF_EVENT_IOC_REFRESH bug");
+        _ioc_enable = PERF_EVENT_IOC_ENABLE;   // opt-in for manual enable/disable
+    } else {
+        _ioc_enable = PERF_EVENT_IOC_REFRESH;  // autodisable perf_event on counter overflow
+    }
+
     adjustFDLimit();
 
     int max_events = OS::getMaxThreadId();