[llvm-branch-commits] [libc] 635c7a9 - Revert "[libc] implement cached process/thread identity (#98989)"
via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Thu Jul 18 13:29:35 PDT 2024
Author: Schrodinger ZHU Yifan
Date: 2024-07-18T13:29:32-07:00
New Revision: 635c7a937b7e4f593af53054bff07c86ca00e51c
URL: https://github.com/llvm/llvm-project/commit/635c7a937b7e4f593af53054bff07c86ca00e51c
DIFF: https://github.com/llvm/llvm-project/commit/635c7a937b7e4f593af53054bff07c86ca00e51c.diff
LOG: Revert "[libc] implement cached process/thread identity (#98989)"
This reverts commit 5c9fc3cdd7acae4ede998f2983e6107f3c0ea36a.
Added:
Modified:
libc/config/config.json
libc/config/linux/aarch64/entrypoints.txt
libc/config/linux/riscv/entrypoints.txt
libc/config/linux/x86_64/entrypoints.txt
libc/docs/configure.rst
libc/docs/dev/undefined_behavior.rst
libc/spec/posix.td
libc/src/__support/OSUtil/CMakeLists.txt
libc/src/__support/OSUtil/linux/CMakeLists.txt
libc/src/__support/threads/CMakeLists.txt
libc/src/__support/threads/linux/CMakeLists.txt
libc/src/__support/threads/linux/rwlock.h
libc/src/__support/threads/linux/thread.cpp
libc/src/__support/threads/thread.h
libc/src/unistd/CMakeLists.txt
libc/src/unistd/getpid.h
libc/src/unistd/linux/CMakeLists.txt
libc/src/unistd/linux/fork.cpp
libc/src/unistd/linux/getpid.cpp
libc/startup/linux/CMakeLists.txt
libc/startup/linux/do_start.cpp
libc/test/integration/src/unistd/CMakeLists.txt
libc/test/integration/src/unistd/fork_test.cpp
libc/test/src/unistd/CMakeLists.txt
Removed:
libc/src/__support/OSUtil/linux/pid.cpp
libc/src/__support/OSUtil/pid.h
libc/src/__support/threads/tid.h
libc/src/unistd/gettid.cpp
libc/src/unistd/gettid.h
libc/test/src/unistd/gettid_test.cpp
################################################################################
diff --git a/libc/config/config.json b/libc/config/config.json
index 0fc88e2b8dbd5..94bfed894c173 100644
--- a/libc/config/config.json
+++ b/libc/config/config.json
@@ -75,16 +75,6 @@
"LIBC_CONF_FREELIST_MALLOC_BUFFER_SIZE": {
"value": 1073741824,
"doc": "Default size for the constinit freelist buffer used for the freelist malloc implementation (default 1o 1GB)."
- },
- },
- "unistd": {
- "LIBC_CONF_ENABLE_TID_CACHE": {
- "value": true,
- "doc": "Enable caching mechanism for gettid to avoid syscall (only effective in fullbuild mode, default to true). Please refer to Undefined Behavior documentation for implications."
- },
- "LIBC_CONF_ENABLE_PID_CACHE": {
- "value": true,
- "doc": "Enable caching mechanism for getpid to avoid syscall (default to true). Please refer to Undefined Behavior documentation for implications."
}
},
"math": {
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index fc2b61226c3fc..208889ba34a59 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -297,7 +297,6 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.geteuid
libc.src.unistd.getpid
libc.src.unistd.getppid
- libc.src.unistd.gettid
libc.src.unistd.getuid
libc.src.unistd.isatty
libc.src.unistd.link
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index b2e68fdaa86e9..266c94d54a9df 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -296,7 +296,6 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.geteuid
libc.src.unistd.getpid
libc.src.unistd.getppid
- libc.src.unistd.gettid
libc.src.unistd.getuid
libc.src.unistd.isatty
libc.src.unistd.link
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 9074bd8aea1f1..cbdee084aa199 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -315,7 +315,6 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.geteuid
libc.src.unistd.getpid
libc.src.unistd.getppid
- libc.src.unistd.gettid
libc.src.unistd.getuid
libc.src.unistd.isatty
libc.src.unistd.link
diff --git a/libc/docs/configure.rst b/libc/docs/configure.rst
index 5c55e4ab0f181..dfb35f6a6611a 100644
--- a/libc/docs/configure.rst
+++ b/libc/docs/configure.rst
@@ -52,6 +52,3 @@ to learn about the defaults for your platform and target.
* **"string" options**
- ``LIBC_CONF_MEMSET_X86_USE_SOFTWARE_PREFETCHING``: Inserts prefetch for write instructions (PREFETCHW) for memset on x86 to recover performance when hardware prefetcher is disabled.
- ``LIBC_CONF_STRING_UNSAFE_WIDE_READ``: Read more than a byte at a time to perform byte-string operations like strlen.
-* **"unistd" options**
- - ``LIBC_CONF_ENABLE_PID_CACHE``: Enable caching mechanism for getpid to avoid syscall (default to true). Please refer to Undefined Behavior documentation for implications.
- - ``LIBC_CONF_ENABLE_TID_CACHE``: Enable caching mechanism for gettid to avoid syscall (only effective in fullbuild mode, default to true). Please refer to Undefined Behavior documentation for implications.
diff --git a/libc/docs/dev/undefined_behavior.rst b/libc/docs/dev/undefined_behavior.rst
index b712780222aa3..3faae3134ce2a 100644
--- a/libc/docs/dev/undefined_behavior.rst
+++ b/libc/docs/dev/undefined_behavior.rst
@@ -93,26 +93,3 @@ direction in this case.
Non-const Constant Return Values
--------------------------------
Some libc functions, like ``dlerror()``, return ``char *`` instead of ``const char *`` and then tell the caller they promise not to to modify this value. Any modification of this value is undefined behavior.
-
-Cached ``getpid/gettid``
-------------------------
-Since version ``2.25``, glibc removes its cache mechanism for ``getpid/gettid``
-(See the history section in https://man7.org/linux/man-pages/man2/getpid.2.html).
-LLVM's libc still implements the cache as it is useful for fast deadlock detection.
-The cache mechanism is also implemented in MUSL and bionic. The tid/pid cache can
-be disabled by setting ``LIBC_CONF_ENABLE_TID_CACHE`` and ``LIBC_CONF_ENABLE_PID_CACHE``
-to ``false`` respectively.
-
-Unwrapped ``SYS_clone/SYS_fork/SYS_vfork``
-------------------------------------------
-It is highly discouraged to use unwrapped ``SYS_clone/SYS_fork/SYS_vfork``.
-First, calling such syscalls without provided libc wrappers ignores
-all the ``pthread_atfork`` entries as libc can no longer detect the ``fork``.
-Second, libc relies on the ``fork/clone`` wrappers to correctly maintain cache for
-process id and thread id, and other important process-specific states such as the list
-of robust mutexes. Third, even if the user is to call ``exec*`` functions immediately,
-there can still be other unexpected issues. For instance, there can be signal handlers
-inherited from parent process triggered inside the instruction window between ``fork``
-and ``exec*``. As libc failed to maintain its internal states correctly, even though the
-functions used inside the signal handlers are marked as ``async-signal-safe`` (such as
-``getpid``), they will still return wrong values or lead to other even worse situations.
diff --git a/libc/spec/posix.td b/libc/spec/posix.td
index 48f743dff4e6f..1878b1ee2ae41 100644
--- a/libc/spec/posix.td
+++ b/libc/spec/posix.td
@@ -546,11 +546,6 @@ def POSIX : StandardSpec<"POSIX"> {
RetValSpec<PidT>,
[ArgSpec<VoidType>]
>,
- FunctionSpec<
- "gettid",
- RetValSpec<PidT>,
- [ArgSpec<VoidType>]
- >,
FunctionSpec<
"getuid",
RetValSpec<UidT>,
@@ -606,6 +601,16 @@ def POSIX : StandardSpec<"POSIX"> {
RetValSpec<IntType>,
[ArgSpec<ConstCharPtr>]
>,
+ FunctionSpec<
+ "getpid",
+ RetValSpec<IntType>,
+ [ArgSpec<VoidType>]
+ >,
+ FunctionSpec<
+ "getppid",
+ RetValSpec<IntType>,
+ [ArgSpec<VoidType>]
+ >,
FunctionSpec<
"link",
RetValSpec<IntType>,
diff --git a/libc/src/__support/OSUtil/CMakeLists.txt b/libc/src/__support/OSUtil/CMakeLists.txt
index 517f888178718..94d1042ccbb4a 100644
--- a/libc/src/__support/OSUtil/CMakeLists.txt
+++ b/libc/src/__support/OSUtil/CMakeLists.txt
@@ -15,20 +15,3 @@ add_object_library(
DEPENDS
${target_os_util}
)
-
-if (LIBC_CONF_ENABLE_PID_CACHE)
- set(libc_copt_enable_pid_cache 1)
-else()
- set(libc_copt_enable_pid_cache 0)
-endif()
-
-if(TARGET libc.src.__support.OSUtil.${LIBC_TARGET_OS}.pid)
- add_object_library(
- pid
- ALIAS
- DEPENDS
- .${LIBC_TARGET_OS}.pid
- COMPILE_OPTIONS
- -DLIBC_COPT_ENABLE_PID_CACHE=${libc_copt_enable_pid_cache}
- )
-endif()
diff --git a/libc/src/__support/OSUtil/linux/CMakeLists.txt b/libc/src/__support/OSUtil/linux/CMakeLists.txt
index 95a83d77d0257..089cad454d534 100644
--- a/libc/src/__support/OSUtil/linux/CMakeLists.txt
+++ b/libc/src/__support/OSUtil/linux/CMakeLists.txt
@@ -23,16 +23,3 @@ add_object_library(
libc.hdr.types.struct_f_owner_ex
libc.hdr.types.off_t
)
-
-add_object_library(
- pid
- SRCS
- pid.cpp
- HDRS
- ../pid.h
- DEPENDS
- libc.src.__support.OSUtil.osutil
- libc.src.__support.common
- libc.hdr.types.pid_t
- libc.include.sys_syscall
-)
diff --git a/libc/src/__support/OSUtil/linux/pid.cpp b/libc/src/__support/OSUtil/linux/pid.cpp
deleted file mode 100644
index a8499af596229..0000000000000
--- a/libc/src/__support/OSUtil/linux/pid.cpp
+++ /dev/null
@@ -1,20 +0,0 @@
-//===------------ pid_t utilities implementation ----------------*- C++ -*-===//
-//
-// 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 "src/__support/OSUtil/pid.h"
-#include "src/__support/OSUtil/syscall.h"
-#include <sys/syscall.h>
-
-namespace LIBC_NAMESPACE_DECL {
-
-pid_t ProcessIdentity::cache = -1;
-pid_t ProcessIdentity::get_uncached() {
- return syscall_impl<pid_t>(SYS_getpid);
-}
-
-} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/OSUtil/pid.h b/libc/src/__support/OSUtil/pid.h
deleted file mode 100644
index d723abe728569..0000000000000
--- a/libc/src/__support/OSUtil/pid.h
+++ /dev/null
@@ -1,41 +0,0 @@
-//===------------ pid_t utilities -------------------------------*- C++ -*-===//
-//
-// 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___SUPPORT_OSUTIL_PID_H
-#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_PID_H
-#include "hdr/types/pid_t.h"
-#include "src/__support/macros/attributes.h"
-#include "src/__support/macros/optimization.h"
-
-#ifndef LIBC_COPT_ENABLE_PID_CACHE
-#define LIBC_COPT_ENABLE_PID_CACHE 1
-#endif
-
-namespace LIBC_NAMESPACE_DECL {
-
-class ProcessIdentity {
- static LIBC_INLINE_VAR thread_local bool fork_inflight = true;
- static pid_t cache;
- static pid_t get_uncached();
-
-public:
- LIBC_INLINE static void start_fork() { fork_inflight = true; }
- LIBC_INLINE static void end_fork() { fork_inflight = false; }
- LIBC_INLINE static void refresh_cache() { cache = get_uncached(); }
- LIBC_INLINE static pid_t get() {
-#if LIBC_COPT_ENABLE_PID_CACHE
- if (LIBC_LIKELY(!fork_inflight))
- return cache;
-#endif
- return get_uncached();
- }
-};
-
-} // namespace LIBC_NAMESPACE_DECL
-
-#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_PID_H
diff --git a/libc/src/__support/threads/CMakeLists.txt b/libc/src/__support/threads/CMakeLists.txt
index f1a2f162acfc2..d2e46b8e2574e 100644
--- a/libc/src/__support/threads/CMakeLists.txt
+++ b/libc/src/__support/threads/CMakeLists.txt
@@ -44,12 +44,6 @@ if(TARGET libc.src.__support.threads.${LIBC_TARGET_OS}.mutex)
)
endif()
-if (LIBC_CONF_ENABLE_TID_CACHE)
- set(libc_copt_enable_tid_cache 1)
-else()
- set(libc_copt_enable_tid_cache 0)
-endif()
-
add_header_library(
thread_common
HDRS
@@ -60,9 +54,6 @@ add_header_library(
libc.src.__support.CPP.optional
libc.src.__support.CPP.string_view
libc.src.__support.CPP.stringstream
- libc.hdr.types.pid_t
- COMPILE_OPTIONS
- -DLIBC_COPT_ENABLE_TID_CACHE=${libc_copt_enable_tid_cache}
)
if(TARGET libc.src.__support.threads.${LIBC_TARGET_OS}.thread)
@@ -98,21 +89,3 @@ if(TARGET libc.src.__support.threads.${LIBC_TARGET_OS}.CndVar)
.${LIBC_TARGET_OS}.CndVar
)
endif()
-
-set(tid_dep)
-if (LLVM_LIBC_FULL_BUILD)
- list(APPEND tid_dep libc.src.__support.thread)
-else()
- list(APPEND tid_dep libc.src.__support.OSUtil.osutil)
- list(APPEND tid_dep libc.include.sys_syscall)
-endif()
-
-add_header_library(
- tid
- HDRS
- tid.h
- DEPENDS
- libc.src.__support.common
- libc.hdr.types.pid_t
- ${tid_dep}
-)
diff --git a/libc/src/__support/threads/linux/CMakeLists.txt b/libc/src/__support/threads/linux/CMakeLists.txt
index d86441dd67cd7..8b7971584e77e 100644
--- a/libc/src/__support/threads/linux/CMakeLists.txt
+++ b/libc/src/__support/threads/linux/CMakeLists.txt
@@ -55,7 +55,6 @@ add_header_library(
libc.src.__support.common
libc.src.__support.OSUtil.osutil
libc.src.__support.CPP.limits
- libc.src.__support.threads.tid
COMPILE_OPTIONS
-DLIBC_COPT_RWLOCK_DEFAULT_SPIN_COUNT=${LIBC_CONF_RWLOCK_DEFAULT_SPIN_COUNT}
${monotonicity_flags}
diff --git a/libc/src/__support/threads/linux/rwlock.h b/libc/src/__support/threads/linux/rwlock.h
index cae8aa6410686..d2fb0ce1a3c08 100644
--- a/libc/src/__support/threads/linux/rwlock.h
+++ b/libc/src/__support/threads/linux/rwlock.h
@@ -23,7 +23,6 @@
#include "src/__support/threads/linux/futex_word.h"
#include "src/__support/threads/linux/raw_mutex.h"
#include "src/__support/threads/sleep.h"
-#include "src/__support/threads/tid.h"
#ifndef LIBC_COPT_RWLOCK_DEFAULT_SPIN_COUNT
#define LIBC_COPT_RWLOCK_DEFAULT_SPIN_COUNT 100
@@ -337,6 +336,8 @@ class RwLock {
LIBC_INLINE Role get_preference() const {
return static_cast<Role>(preference);
}
+ // TODO: use cached thread id once implemented.
+ LIBC_INLINE static pid_t gettid() { return syscall_impl<pid_t>(SYS_gettid); }
template <Role role> LIBC_INLINE LockResult try_lock(RwState &old) {
if constexpr (role == Role::Reader) {
@@ -358,7 +359,7 @@ class RwLock {
if (LIBC_LIKELY(old.compare_exchange_weak_with(
state, old.set_writer_bit(), cpp::MemoryOrder::ACQUIRE,
cpp::MemoryOrder::RELAXED))) {
- writer_tid.store(gettid_inline(), cpp::MemoryOrder::RELAXED);
+ writer_tid.store(gettid(), cpp::MemoryOrder::RELAXED);
return LockResult::Success;
}
// Notice that old is updated by the compare_exchange_weak_with
@@ -393,7 +394,7 @@ class RwLock {
unsigned spin_count = LIBC_COPT_RWLOCK_DEFAULT_SPIN_COUNT) {
// Phase 1: deadlock detection.
// A deadlock happens if this is a RAW/WAW lock in the same thread.
- if (writer_tid.load(cpp::MemoryOrder::RELAXED) == gettid_inline())
+ if (writer_tid.load(cpp::MemoryOrder::RELAXED) == gettid())
return LockResult::Deadlock;
#if LIBC_COPT_TIMEOUT_ENSURE_MONOTONICITY
@@ -519,7 +520,7 @@ class RwLock {
if (old.has_active_writer()) {
// The lock is held by a writer.
// Check if we are the owner of the lock.
- if (writer_tid.load(cpp::MemoryOrder::RELAXED) != gettid_inline())
+ if (writer_tid.load(cpp::MemoryOrder::RELAXED) != gettid())
return LockResult::PermissionDenied;
// clear writer tid.
writer_tid.store(0, cpp::MemoryOrder::RELAXED);
diff --git a/libc/src/__support/threads/linux/thread.cpp b/libc/src/__support/threads/linux/thread.cpp
index c8ad086f3d1cb..36b4a88eba9b4 100644
--- a/libc/src/__support/threads/linux/thread.cpp
+++ b/libc/src/__support/threads/linux/thread.cpp
@@ -518,6 +518,4 @@ void thread_exit(ThreadReturnValue retval, ThreadStyle style) {
__builtin_unreachable();
}
-pid_t Thread::get_uncached_tid() { return syscall_impl<pid_t>(SYS_gettid); }
-
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/threads/thread.h b/libc/src/__support/threads/thread.h
index 1805b6fd6182a..ce23a880e048a 100644
--- a/libc/src/__support/threads/thread.h
+++ b/libc/src/__support/threads/thread.h
@@ -9,11 +9,6 @@
#ifndef LLVM_LIBC_SRC___SUPPORT_THREADS_THREAD_H
#define LLVM_LIBC_SRC___SUPPORT_THREADS_THREAD_H
-#ifndef LIBC_COPT_ENABLE_TID_CACHE
-#define LIBC_COPT_ENABLE_TID_CACHE 1
-#endif
-
-#include "hdr/types/pid_t.h"
#include "src/__support/CPP/atomic.h"
#include "src/__support/CPP/optional.h"
#include "src/__support/CPP/string_view.h"
@@ -108,7 +103,7 @@ struct alignas(STACK_ALIGNMENT) ThreadAttributes {
uintptr_t tls; // Address to the thread TLS memory
uintptr_t tls_size; // The size of area pointed to by |tls|.
unsigned char owned_stack; // Indicates if the thread owns this stack memory
- pid_t tid;
+ int tid;
ThreadStyle style;
ThreadReturnValue retval;
ThreadAtExitCallbackMgr *atexit_callback_mgr;
@@ -233,26 +228,6 @@ struct Thread {
// Return the name of the thread in |name|. Return the error number of error.
int get_name(cpp::StringStream &name) const;
-
- static pid_t get_uncached_tid();
-
- LIBC_INLINE void refresh_tid(pid_t cached = -1) {
- if (cached >= 0)
- this->attrib->tid = cached;
- else
- this->attrib->tid = get_uncached_tid();
- }
- LIBC_INLINE void invalidate_tid() { this->attrib->tid = -1; }
-
- LIBC_INLINE pid_t get_tid() {
-#if LIBC_COPT_ENABLE_TID_CACHE
- if (LIBC_UNLIKELY(this->attrib->tid < 0))
- return get_uncached_tid();
- return this->attrib->tid;
-#else
- return get_uncached_tid();
-#endif
- }
};
extern LIBC_THREAD_LOCAL Thread self;
diff --git a/libc/src/__support/threads/tid.h b/libc/src/__support/threads/tid.h
deleted file mode 100644
index a575cff508a0f..0000000000000
--- a/libc/src/__support/threads/tid.h
+++ /dev/null
@@ -1,34 +0,0 @@
-//===--- Tid wrapper --------------------------------------------*- C++ -*-===//
-//
-// 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___SUPPORT_THREADS_TID_H
-#define LLVM_LIBC_SRC___SUPPORT_THREADS_TID_H
-
-// This header is for internal usage which automatically dispatches full build
-// and overlay build behaviors.
-
-#include "hdr/types/pid_t.h"
-#include "src/__support/common.h"
-#ifdef LIBC_FULL_BUILD
-#include "src/__support/threads/thread.h"
-#else
-#include "src/__support/OSUtil/syscall.h"
-#include <sys/syscall.h>
-#endif // LIBC_FULL_BUILD
-
-namespace LIBC_NAMESPACE_DECL {
-LIBC_INLINE pid_t gettid_inline() {
-#ifdef LIBC_FULL_BUILD
- return self.get_tid();
-#else
- return syscall_impl<pid_t>(SYS_gettid);
-#endif
-}
-} // namespace LIBC_NAMESPACE_DECL
-
-#endif // LLVM_LIBC_SRC___SUPPORT_THREADS_TID_H
diff --git a/libc/src/unistd/CMakeLists.txt b/libc/src/unistd/CMakeLists.txt
index ec767128588f6..ddafcd7c92f21 100644
--- a/libc/src/unistd/CMakeLists.txt
+++ b/libc/src/unistd/CMakeLists.txt
@@ -333,13 +333,3 @@ add_entrypoint_external(
add_entrypoint_external(
opterr
)
-
-add_entrypoint_object(
- gettid
- SRCS
- gettid.cpp
- HDRS
- gettid.h
- DEPENDS
- libc.src.__support.threads.tid
-)
diff --git a/libc/src/unistd/getpid.h b/libc/src/unistd/getpid.h
index 5812df0dfecd6..c3c55b0c06b10 100644
--- a/libc/src/unistd/getpid.h
+++ b/libc/src/unistd/getpid.h
@@ -9,12 +9,12 @@
#ifndef LLVM_LIBC_SRC_UNISTD_GETPID_H
#define LLVM_LIBC_SRC_UNISTD_GETPID_H
-#include "hdr/types/pid_t.h"
#include "src/__support/macros/config.h"
+#include <unistd.h>
namespace LIBC_NAMESPACE_DECL {
-pid_t getpid(void);
+pid_t getpid();
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/unistd/gettid.cpp b/libc/src/unistd/gettid.cpp
deleted file mode 100644
index 6d8ed65fb753d..0000000000000
--- a/libc/src/unistd/gettid.cpp
+++ /dev/null
@@ -1,17 +0,0 @@
-//===-- Implementation file for gettid --------------------------*- C++ -*-===//
-//
-// 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 "src/unistd/gettid.h"
-#include "src/__support/common.h"
-#include "src/__support/threads/tid.h"
-
-namespace LIBC_NAMESPACE_DECL {
-
-LLVM_LIBC_FUNCTION(pid_t, gettid, (void)) { return gettid_inline(); }
-
-} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/unistd/gettid.h b/libc/src/unistd/gettid.h
deleted file mode 100644
index 42283191be49b..0000000000000
--- a/libc/src/unistd/gettid.h
+++ /dev/null
@@ -1,21 +0,0 @@
-//===-- Implementation header for gettid ------------------------*- C++ -*-===//
-//
-// 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_UNISTD_GETTID_H
-#define LLVM_LIBC_SRC_UNISTD_GETTID_H
-
-#include "hdr/types/pid_t.h"
-#include "src/__support/common.h"
-
-namespace LIBC_NAMESPACE_DECL {
-
-pid_t gettid(void);
-
-} // namespace LIBC_NAMESPACE_DECL
-
-#endif // LLVM_LIBC_SRC_UNISTD_GETTID_H
diff --git a/libc/src/unistd/linux/CMakeLists.txt b/libc/src/unistd/linux/CMakeLists.txt
index 651ea60d07a30..7e733d7f002c3 100644
--- a/libc/src/unistd/linux/CMakeLists.txt
+++ b/libc/src/unistd/linux/CMakeLists.txt
@@ -101,7 +101,6 @@ add_entrypoint_object(
libc.include.sys_syscall
libc.src.__support.threads.fork_callbacks
libc.src.__support.OSUtil.osutil
- libc.src.__support.OSUtil.pid
libc.src.__support.threads.thread
libc.src.errno.errno
)
@@ -205,7 +204,8 @@ add_entrypoint_object(
../getpid.h
DEPENDS
libc.include.unistd
- libc.src.__support.OSUtil.pid
+ libc.include.sys_syscall
+ libc.src.__support.OSUtil.osutil
)
add_entrypoint_object(
diff --git a/libc/src/unistd/linux/fork.cpp b/libc/src/unistd/linux/fork.cpp
index 8fe1881733f34..7d47665b16d3f 100644
--- a/libc/src/unistd/linux/fork.cpp
+++ b/libc/src/unistd/linux/fork.cpp
@@ -8,14 +8,13 @@
#include "src/unistd/fork.h"
-#include "src/__support/OSUtil/pid.h"
#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
#include "src/__support/common.h"
#include "src/__support/macros/config.h"
#include "src/__support/threads/fork_callbacks.h"
#include "src/__support/threads/thread.h" // For thread self object
-#include "src/errno/libc_errno.h"
+#include "src/errno/libc_errno.h"
#include <signal.h> // For SIGCHLD
#include <sys/syscall.h> // For syscall numbers.
@@ -26,14 +25,6 @@ namespace LIBC_NAMESPACE_DECL {
LLVM_LIBC_FUNCTION(pid_t, fork, (void)) {
invoke_prepare_callbacks();
-
- // Invalidate tid/pid cache before fork to avoid post fork signal handler from
- // getting wrong values. gettid() is not async-signal-safe, but let's provide
- // our best efforts here.
- pid_t parent_tid = self.get_tid();
- self.invalidate_tid();
- ProcessIdentity::start_fork();
-
#ifdef SYS_fork
pid_t ret = LIBC_NAMESPACE::syscall_impl<pid_t>(SYS_fork);
#elif defined(SYS_clone)
@@ -41,6 +32,15 @@ LLVM_LIBC_FUNCTION(pid_t, fork, (void)) {
#else
#error "fork and clone syscalls not available."
#endif
+ if (ret == 0) {
+ // Return value is 0 in the child process.
+ // The child is created with a single thread whose self object will be a
+ // copy of parent process' thread which called fork. So, we have to fix up
+ // the child process' self object with the new process' tid.
+ self.attrib->tid = LIBC_NAMESPACE::syscall_impl<pid_t>(SYS_gettid);
+ invoke_child_callbacks();
+ return 0;
+ }
if (ret < 0) {
// Error case, a child process was not created.
@@ -48,18 +48,6 @@ LLVM_LIBC_FUNCTION(pid_t, fork, (void)) {
return -1;
}
- // Child process
- if (ret == 0) {
- self.refresh_tid();
- ProcessIdentity::refresh_cache();
- ProcessIdentity::end_fork();
- invoke_child_callbacks();
- return 0;
- }
-
- // Parent process
- self.refresh_tid(parent_tid);
- ProcessIdentity::end_fork();
invoke_parent_callbacks();
return ret;
}
diff --git a/libc/src/unistd/linux/getpid.cpp b/libc/src/unistd/linux/getpid.cpp
index 65d6c8a3bea95..b24c86a15990f 100644
--- a/libc/src/unistd/linux/getpid.cpp
+++ b/libc/src/unistd/linux/getpid.cpp
@@ -7,10 +7,17 @@
//===----------------------------------------------------------------------===//
#include "src/unistd/getpid.h"
-#include "src/__support/OSUtil/pid.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+#include <sys/syscall.h> // For syscall numbers.
+
namespace LIBC_NAMESPACE_DECL {
-LLVM_LIBC_FUNCTION(pid_t, getpid, (void)) { return ProcessIdentity::get(); }
+LLVM_LIBC_FUNCTION(pid_t, getpid, ()) {
+ return LIBC_NAMESPACE::syscall_impl<pid_t>(SYS_getpid);
+}
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/startup/linux/CMakeLists.txt b/libc/startup/linux/CMakeLists.txt
index 585edf20f65be..336c5d0f6bfa2 100644
--- a/libc/startup/linux/CMakeLists.txt
+++ b/libc/startup/linux/CMakeLists.txt
@@ -101,7 +101,6 @@ add_object_library(
libc.include.llvm-libc-macros.link_macros
libc.src.__support.threads.thread
libc.src.__support.OSUtil.osutil
- libc.src.__support.OSUtil.pid
libc.src.stdlib.exit
libc.src.stdlib.atexit
libc.src.unistd.environ
diff --git a/libc/startup/linux/do_start.cpp b/libc/startup/linux/do_start.cpp
index 4047c06ff25c1..824c0e1cf8f26 100644
--- a/libc/startup/linux/do_start.cpp
+++ b/libc/startup/linux/do_start.cpp
@@ -7,7 +7,6 @@
//===----------------------------------------------------------------------===//
#include "startup/linux/do_start.h"
#include "include/llvm-libc-macros/link-macros.h"
-#include "src/__support/OSUtil/pid.h"
#include "src/__support/OSUtil/syscall.h"
#include "src/__support/macros/config.h"
#include "src/__support/threads/thread.h"
@@ -128,10 +127,6 @@ static ThreadAttributes main_thread_attrib;
if (tls.size != 0 && !set_thread_ptr(tls.tp))
syscall_impl<long>(SYS_exit, 1);
- // Validate process identity cache (TLS needed).
- ProcessIdentity::refresh_cache();
- ProcessIdentity::end_fork();
-
self.attrib = &main_thread_attrib;
main_thread_attrib.atexit_callback_mgr =
internal::get_thread_atexit_callback_mgr();
diff --git a/libc/test/integration/src/unistd/CMakeLists.txt b/libc/test/integration/src/unistd/CMakeLists.txt
index f50405d0925e2..3f18231209512 100644
--- a/libc/test/integration/src/unistd/CMakeLists.txt
+++ b/libc/test/integration/src/unistd/CMakeLists.txt
@@ -31,10 +31,6 @@ add_integration_test(
libc.src.sys.wait.wait4
libc.src.sys.wait.waitpid
libc.src.unistd.fork
- libc.src.unistd.getpid
- libc.src.unistd.gettid
- libc.src.stdlib.exit
- libc.include.sys_syscall
)
if((${LIBC_TARGET_OS} STREQUAL "linux") AND (${LIBC_TARGET_ARCHITECTURE_IS_X86}))
diff --git a/libc/test/integration/src/unistd/fork_test.cpp b/libc/test/integration/src/unistd/fork_test.cpp
index 4b82d5f195627..9c9213ed46316 100644
--- a/libc/test/integration/src/unistd/fork_test.cpp
+++ b/libc/test/integration/src/unistd/fork_test.cpp
@@ -6,21 +6,17 @@
//
//===----------------------------------------------------------------------===//
-#include "src/__support/OSUtil/syscall.h"
#include "src/pthread/pthread_atfork.h"
#include "src/signal/raise.h"
-#include "src/stdlib/exit.h"
#include "src/sys/wait/wait.h"
#include "src/sys/wait/wait4.h"
#include "src/sys/wait/waitpid.h"
#include "src/unistd/fork.h"
-#include "src/unistd/getpid.h"
-#include "src/unistd/gettid.h"
+
#include "test/IntegrationTest/test.h"
#include <errno.h>
#include <signal.h>
-#include <sys/syscall.h>
#include <sys/wait.h>
#include <unistd.h>
@@ -144,25 +140,7 @@ void fork_with_atfork_callbacks() {
ASSERT_NE(child, DONE);
}
-void fork_pid_tid_test() {
- pid_t pid = fork();
- ASSERT_TRUE(pid >= 0);
- ASSERT_EQ(LIBC_NAMESPACE::gettid(),
- LIBC_NAMESPACE::syscall_impl<pid_t>(SYS_gettid));
- ASSERT_EQ(LIBC_NAMESPACE::getpid(),
- LIBC_NAMESPACE::syscall_impl<pid_t>(SYS_getpid));
-
- if (pid == 0) {
- LIBC_NAMESPACE::exit(0);
- } else {
- int status;
- LIBC_NAMESPACE::waitpid(pid, &status, 0);
- ASSERT_EQ(status, 0);
- }
-}
-
TEST_MAIN(int argc, char **argv, char **envp) {
- fork_pid_tid_test();
fork_and_wait_normal_exit();
fork_and_wait4_normal_exit();
fork_and_waitpid_normal_exit();
diff --git a/libc/test/src/unistd/CMakeLists.txt b/libc/test/src/unistd/CMakeLists.txt
index f8292653081f1..332455b791aee 100644
--- a/libc/test/src/unistd/CMakeLists.txt
+++ b/libc/test/src/unistd/CMakeLists.txt
@@ -378,16 +378,6 @@ add_libc_unittest(
libc.src.unistd.getpid
)
-add_libc_unittest(
- gettid_test
- SUITE
- libc_unistd_unittests
- SRCS
- gettid_test.cpp
- DEPENDS
- libc.src.unistd.gettid
-)
-
add_libc_unittest(
getppid_test
SUITE
diff --git a/libc/test/src/unistd/gettid_test.cpp b/libc/test/src/unistd/gettid_test.cpp
deleted file mode 100644
index c2330f4002279..0000000000000
--- a/libc/test/src/unistd/gettid_test.cpp
+++ /dev/null
@@ -1,15 +0,0 @@
-//===-- Unittests for gettid ----------------------------------------------===//
-//
-// 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 "src/unistd/gettid.h"
-#include "test/UnitTest/Test.h"
-
-TEST(LlvmLibcGetTidTest, SmokeTest) {
- // gettid always succeeds. So, we just call it as a smoke test.
- ASSERT_GT(LIBC_NAMESPACE::gettid(), 0);
-}
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