[libc-commits] [libc] 91c0fdf - [libc] add posix_mutex_trylock support (#191531)
via libc-commits
libc-commits at lists.llvm.org
Mon Apr 13 07:54:32 PDT 2026
Author: Schrodinger ZHU Yifan
Date: 2026-04-13T10:54:28-04:00
New Revision: 91c0fdfe13928838864d9618ea28dcbe9a112b8c
URL: https://github.com/llvm/llvm-project/commit/91c0fdfe13928838864d9618ea28dcbe9a112b8c
DIFF: https://github.com/llvm/llvm-project/commit/91c0fdfe13928838864d9618ea28dcbe9a112b8c.diff
LOG: [libc] add posix_mutex_trylock support (#191531)
Expose existing trylock internal operation to posix interface.
POSIX.1-2024 only specifies the `EBUSY` error case.
Assisted-by: Codex with gpt-5.4 default fast
Added:
libc/src/pthread/pthread_mutex_trylock.cpp
libc/src/pthread/pthread_mutex_trylock.h
Modified:
libc/config/linux/aarch64/entrypoints.txt
libc/config/linux/riscv/entrypoints.txt
libc/config/linux/x86_64/entrypoints.txt
libc/include/pthread.yaml
libc/src/__support/threads/mutex.h
libc/src/pthread/CMakeLists.txt
libc/test/integration/src/pthread/CMakeLists.txt
libc/test/integration/src/pthread/pthread_mutex_test.cpp
Removed:
################################################################################
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index c0d2f6c39f9f9..9e9752dcde915 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -1011,6 +1011,7 @@ if(LLVM_LIBC_FULL_BUILD)
libc.src.pthread.pthread_mutex_destroy
libc.src.pthread.pthread_mutex_init
libc.src.pthread.pthread_mutex_lock
+ libc.src.pthread.pthread_mutex_trylock
libc.src.pthread.pthread_mutex_unlock
libc.src.pthread.pthread_mutexattr_destroy
libc.src.pthread.pthread_mutexattr_getpshared
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index fe393241ce8d0..0e1e806362dcd 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -1144,6 +1144,7 @@ if(LLVM_LIBC_FULL_BUILD)
libc.src.pthread.pthread_mutex_destroy
libc.src.pthread.pthread_mutex_init
libc.src.pthread.pthread_mutex_lock
+ libc.src.pthread.pthread_mutex_trylock
libc.src.pthread.pthread_mutex_unlock
libc.src.pthread.pthread_mutexattr_destroy
libc.src.pthread.pthread_mutexattr_getpshared
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 184aa57016ce5..9476ebbad1517 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -1202,6 +1202,7 @@ if(LLVM_LIBC_FULL_BUILD)
libc.src.pthread.pthread_mutex_destroy
libc.src.pthread.pthread_mutex_init
libc.src.pthread.pthread_mutex_lock
+ libc.src.pthread.pthread_mutex_trylock
libc.src.pthread.pthread_mutex_unlock
libc.src.pthread.pthread_mutexattr_destroy
libc.src.pthread.pthread_mutexattr_getpshared
diff --git a/libc/include/pthread.yaml b/libc/include/pthread.yaml
index cfbd726fa1f0c..782a37c8ffad2 100644
--- a/libc/include/pthread.yaml
+++ b/libc/include/pthread.yaml
@@ -221,6 +221,10 @@ functions:
return_type: int
arguments:
- type: pthread_mutex_t *
+ - name: pthread_mutex_trylock
+ return_type: int
+ arguments:
+ - type: pthread_mutex_t *
- name: pthread_mutex_unlock
return_type: int
arguments:
diff --git a/libc/src/__support/threads/mutex.h b/libc/src/__support/threads/mutex.h
index 25feea891e429..76a656729eef7 100644
--- a/libc/src/__support/threads/mutex.h
+++ b/libc/src/__support/threads/mutex.h
@@ -22,7 +22,7 @@
//
// MutexError lock();
// MutexError trylock();
-// MutexError timedlock(...);
+// MutexError timed_lock(...);
// MutexError unlock();
// MutexError reset(); // Used to reset inconsistent robust mutexes.
//
@@ -54,12 +54,14 @@ namespace LIBC_NAMESPACE_DECL {
/// complete Mutex locks in general cannot be implemented on the GPU, or on some
/// baremetal platforms. We simply define the Mutex interface and require that
/// only a single thread executes code requiring a mutex lock.
+// TODO: declare abstract interface for timed_lock
struct Mutex {
LIBC_INLINE constexpr Mutex(bool, bool, bool, bool) {}
LIBC_INLINE MutexError lock() { return MutexError::NONE; }
LIBC_INLINE MutexError unlock() { return MutexError::NONE; }
LIBC_INLINE MutexError reset() { return MutexError::NONE; }
+ LIBC_INLINE MutexError trylock() { return MutexError::NONE; }
};
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/pthread/CMakeLists.txt b/libc/src/pthread/CMakeLists.txt
index 5e41dbdf1c84f..943b29d99f9ee 100644
--- a/libc/src/pthread/CMakeLists.txt
+++ b/libc/src/pthread/CMakeLists.txt
@@ -361,6 +361,17 @@ add_entrypoint_object(
libc.src.__support.threads.mutex
)
+add_entrypoint_object(
+ pthread_mutex_trylock
+ SRCS
+ pthread_mutex_trylock.cpp
+ HDRS
+ pthread_mutex_trylock.h
+ DEPENDS
+ libc.include.pthread
+ libc.src.__support.threads.mutex
+)
+
add_entrypoint_object(
pthread_mutex_unlock
SRCS
diff --git a/libc/src/pthread/pthread_mutex_trylock.cpp b/libc/src/pthread/pthread_mutex_trylock.cpp
new file mode 100644
index 0000000000000..1920a49f2a8d3
--- /dev/null
+++ b/libc/src/pthread/pthread_mutex_trylock.cpp
@@ -0,0 +1,26 @@
+//===-- Linux implementation of the pthread_mutex_trylock function --------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "pthread_mutex_trylock.h"
+
+#include "hdr/errno_macros.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/threads/mutex.h"
+#include "src/__support/threads/mutex_common.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+// The implementation currently handles only plain mutexes.
+LLVM_LIBC_FUNCTION(int, pthread_mutex_trylock, (pthread_mutex_t * mutex)) {
+ if (reinterpret_cast<Mutex *>(mutex)->try_lock() == MutexError::BUSY)
+ return EBUSY;
+ return 0;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/pthread/pthread_mutex_trylock.h b/libc/src/pthread/pthread_mutex_trylock.h
new file mode 100644
index 0000000000000..0a826da2e8a10
--- /dev/null
+++ b/libc/src/pthread/pthread_mutex_trylock.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for pthread_mutex_trylock function ----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_PTHREAD_PTHREAD_MUTEX_TRYLOCK_H
+#define LLVM_LIBC_SRC_PTHREAD_PTHREAD_MUTEX_TRYLOCK_H
+
+#include "include/llvm-libc-types/pthread_mutex_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int pthread_mutex_trylock(pthread_mutex_t *mutex);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_PTHREAD_PTHREAD_MUTEX_TRYLOCK_H
diff --git a/libc/test/integration/src/pthread/CMakeLists.txt b/libc/test/integration/src/pthread/CMakeLists.txt
index 62f6ed777e522..1cfac7aadf111 100644
--- a/libc/test/integration/src/pthread/CMakeLists.txt
+++ b/libc/test/integration/src/pthread/CMakeLists.txt
@@ -13,6 +13,7 @@ add_integration_test(
libc.src.pthread.pthread_mutex_destroy
libc.src.pthread.pthread_mutex_init
libc.src.pthread.pthread_mutex_lock
+ libc.src.pthread.pthread_mutex_trylock
libc.src.pthread.pthread_mutex_unlock
libc.src.pthread.pthread_create
libc.src.pthread.pthread_join
diff --git a/libc/test/integration/src/pthread/pthread_mutex_test.cpp b/libc/test/integration/src/pthread/pthread_mutex_test.cpp
index d482dcc13f443..488954c0ef255 100644
--- a/libc/test/integration/src/pthread/pthread_mutex_test.cpp
+++ b/libc/test/integration/src/pthread/pthread_mutex_test.cpp
@@ -6,12 +6,14 @@
//
//===----------------------------------------------------------------------===//
+#include "hdr/errno_macros.h"
#include "hdr/stdint_proxy.h" // uintptr_t
#include "src/pthread/pthread_create.h"
#include "src/pthread/pthread_join.h"
#include "src/pthread/pthread_mutex_destroy.h"
#include "src/pthread/pthread_mutex_init.h"
#include "src/pthread/pthread_mutex_lock.h"
+#include "src/pthread/pthread_mutex_trylock.h"
#include "src/pthread/pthread_mutex_unlock.h"
#include "test/IntegrationTest/test.h"
@@ -128,6 +130,19 @@ void wait_and_step() {
LIBC_NAMESPACE::pthread_mutex_destroy(&step_lock);
}
+void trylock_test() {
+ pthread_mutex_t trylock_mutex;
+ ASSERT_EQ(LIBC_NAMESPACE::pthread_mutex_init(&trylock_mutex, nullptr), 0);
+
+ ASSERT_EQ(LIBC_NAMESPACE::pthread_mutex_trylock(&trylock_mutex), 0);
+ ASSERT_EQ(LIBC_NAMESPACE::pthread_mutex_trylock(&trylock_mutex), EBUSY);
+ ASSERT_EQ(LIBC_NAMESPACE::pthread_mutex_unlock(&trylock_mutex), 0);
+ ASSERT_EQ(LIBC_NAMESPACE::pthread_mutex_trylock(&trylock_mutex), 0);
+ ASSERT_EQ(LIBC_NAMESPACE::pthread_mutex_unlock(&trylock_mutex), 0);
+
+ LIBC_NAMESPACE::pthread_mutex_destroy(&trylock_mutex);
+}
+
static constexpr int THREAD_COUNT = 10;
static pthread_mutex_t multiple_waiter_lock;
static pthread_mutex_t counter_lock;
@@ -191,6 +206,7 @@ static pthread_mutex_t test_initializer = PTHREAD_MUTEX_INITIALIZER;
TEST_MAIN() {
relay_counter();
wait_and_step();
+ trylock_test();
multiple_waiters();
return 0;
}
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