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); -} _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
