From patchwork Mon Feb 4 10:04:45 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 31293 Received: (qmail 42563 invoked by alias); 4 Feb 2019 10:04:51 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 42554 invoked by uid 89); 4 Feb 2019 10:04:51 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=Nothing X-HELO: mx1.redhat.com From: Florian Weimer To: libc-alpha@sourceware.org Subject: [PATCH] nptl: Introduce __nptl_main_thread_exited Date: Mon, 04 Feb 2019 11:04:45 +0100 Message-ID: <87tvhjx41u.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 __libc_start_main previously accessed both __nptl_nthreads and __nptl_deallocate_tsd. Move this code into __nptl_main_thread_exited in nptl/pthread_create.c, to concentrate nptl processing logic in the nptl subdirectory. 2019-02-03 Florian Weimer * nptl/pthreadP.h (__nptl_main_thread_exited): Declare. (__nptl_deallocate_tsd): Remove declaration. * sysdeps/nptl/pthread-functions.h (struct pthread_functions): Remove ptr_nthreads, ptr__nptl_deallocate_tsd. Add ptr__nptl_main_thread_exited. (HAVE_PTR_NTHREADS): Remove macro. No longer used. * nptl/pthread_create.c (__nptl_deallocate_tsd): Make static. (__nptl_main_thread_exited): New function. Extracted from __libc_start_main. * nptl/nptl-init.c (pthread_functions): Do not initialize ptr_nthreads, ptr__nptl_deallocate_tsd. Initialize ptr__nptl_main_thread_exited. * csu/libc-start.c (LIBC_START_MAIN): Call __nptl_main_thread_exited on pthread_exit/pthread_cancel. * nptl/pthread_exit.c: Update comment. diff --git a/csu/libc-start.c b/csu/libc-start.c index 5d9c3675fa..23ded05333 100644 --- a/csu/libc-start.c +++ b/csu/libc-start.c @@ -43,12 +43,6 @@ uintptr_t __pointer_chk_guard_local # endif #endif -#ifdef HAVE_PTR_NTHREADS -/* We need atomic operations. */ -# include -#endif - - #ifndef SHARED # include # include @@ -309,30 +303,23 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL), } else { - /* Remove the thread-local data. */ + /* The main is terminating via unwinding, either via + pthread_exit or pthread_cancel. Call into the thread + library, to call deallocate thread-local data. This may + terminate the thread if it is not the last thread. */ # ifdef SHARED - PTHFCT_CALL (ptr__nptl_deallocate_tsd, ()); + PTHFCT_CALL (ptr__nptl_main_thread_exited, ()); # else - extern void __nptl_deallocate_tsd (void) __attribute ((weak)); - __nptl_deallocate_tsd (); + /* The function is only invoked on pthread_exit or + pthread_cancel, which means we necessarily have a definition + for it, and no null pointer check is needed here. */ + extern void __nptl_main_thread_exited (void) + __attribute__ ((weak)) attribute_hidden; + __nptl_main_thread_exited (); # endif - /* One less thread. Decrement the counter. If it is zero we - terminate the entire process. */ + /* Exit status for cancellation. */ result = 0; -# ifdef SHARED - unsigned int *ptr = __libc_pthread_functions.ptr_nthreads; -# ifdef PTR_DEMANGLE - PTR_DEMANGLE (ptr); -# endif -# else - extern unsigned int __nptl_nthreads __attribute ((weak)); - unsigned int *const ptr = &__nptl_nthreads; -# endif - - if (! atomic_decrement_and_test (ptr)) - /* Not much left to do but to exit the thread, not the process. */ - __exit_thread (); } #else /* Nothing fancy, just call the function. */ diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c index b5895fabf3..757397fcb0 100644 --- a/nptl/nptl-init.c +++ b/nptl/nptl-init.c @@ -132,9 +132,8 @@ static const struct pthread_functions pthread_functions = .ptr___pthread_setspecific = __pthread_setspecific, .ptr__pthread_cleanup_push_defer = __pthread_cleanup_push_defer, .ptr__pthread_cleanup_pop_restore = __pthread_cleanup_pop_restore, - .ptr_nthreads = &__nptl_nthreads, .ptr___pthread_unwind = &__pthread_unwind, - .ptr__nptl_deallocate_tsd = __nptl_deallocate_tsd, + .ptr__nptl_main_thread_exited = &__nptl_main_thread_exited, # ifdef SIGSETXID .ptr__nptl_setxid = __nptl_setxid, # endif diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h index 626bd4b096..7277567c58 100644 --- a/nptl/pthreadP.h +++ b/nptl/pthreadP.h @@ -590,7 +590,11 @@ extern void _pthread_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer, extern void _pthread_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer, int execute); -extern void __nptl_deallocate_tsd (void) attribute_hidden; +/* Called from __libc_start_main in csu/libc-start.c (via the nptl + function pointer interface) if the main thread is terminating via + pthread_exit or pthread_cancel (and not via a regular return from + main). */ +void __nptl_main_thread_exited (void) attribute_hidden; extern void __nptl_setxid_error (struct xid_command *cmdp, int error) attribute_hidden; diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c index 2bd2b10727..04d1c6453e 100644 --- a/nptl/pthread_create.c +++ b/nptl/pthread_create.c @@ -245,8 +245,7 @@ __find_in_stack_list (struct pthread *pd) /* Deallocate POSIX thread-local-storage. */ -void -attribute_hidden +static void __nptl_deallocate_tsd (void) { struct pthread *self = THREAD_SELF; @@ -337,6 +336,15 @@ __nptl_deallocate_tsd (void) } } +void +__nptl_main_thread_exited (void) +{ + __nptl_deallocate_tsd (); + + if (! atomic_decrement_and_test (&__nptl_nthreads)) + /* Exit the thread, but not the process. */ + __exit_thread (); +} /* Deallocate a thread's stack after optionally making sure the thread descriptor is still valid. */ diff --git a/nptl/pthread_exit.c b/nptl/pthread_exit.c index abc9019334..a6d56751b0 100644 --- a/nptl/pthread_exit.c +++ b/nptl/pthread_exit.c @@ -29,6 +29,6 @@ __pthread_exit (void *value) } weak_alias (__pthread_exit, pthread_exit) -/* After a thread terminates, __libc_start_main decrements - __nptl_nthreads defined in pthread_create.c. */ +/* Exiting from main via pthread_exit needs a definition of + __nptl_main_thread_exited. */ PTHREAD_STATIC_FN_REQUIRE (__pthread_create) diff --git a/sysdeps/nptl/pthread-functions.h b/sysdeps/nptl/pthread-functions.h index cd5e94d1a6..d95a636220 100644 --- a/sysdeps/nptl/pthread-functions.h +++ b/sysdeps/nptl/pthread-functions.h @@ -88,11 +88,9 @@ struct pthread_functions void (*) (void *), void *); void (*ptr__pthread_cleanup_pop_restore) (struct _pthread_cleanup_buffer *, int); -#define HAVE_PTR_NTHREADS - unsigned int *ptr_nthreads; void (*ptr___pthread_unwind) (__pthread_unwind_buf_t *) __attribute ((noreturn)) __cleanup_fct_attribute; - void (*ptr__nptl_deallocate_tsd) (void); + void (*ptr__nptl_main_thread_exited) (void); int (*ptr__nptl_setxid) (struct xid_command *); void (*ptr_set_robust) (struct pthread *); };