diff options
Diffstat (limited to 'Fix-deadlock-when-pthread_atfork-handler-calls-pthre.patch')
| -rw-r--r-- | Fix-deadlock-when-pthread_atfork-handler-calls-pthre.patch | 754 |
1 files changed, 754 insertions, 0 deletions
diff --git a/Fix-deadlock-when-pthread_atfork-handler-calls-pthre.patch b/Fix-deadlock-when-pthread_atfork-handler-calls-pthre.patch new file mode 100644 index 0000000..97927a9 --- /dev/null +++ b/Fix-deadlock-when-pthread_atfork-handler-calls-pthre.patch @@ -0,0 +1,754 @@ +From ff450cdbdee0b8cb6b9d653d6d2fa892de29be31 Mon Sep 17 00:00:00 2001 +From: Arjun Shankar <arjun@redhat.com> +Date: Tue, 24 May 2022 17:57:36 +0200 +Subject: [PATCH] Fix deadlock when pthread_atfork handler calls pthread_atfork + or dlclose + +In multi-threaded programs, registering via pthread_atfork, +de-registering implicitly via dlclose, or running pthread_atfork +handlers during fork was protected by an internal lock. This meant +that a pthread_atfork handler attempting to register another handler or +dlclose a dynamically loaded library would lead to a deadlock. + +This commit fixes the deadlock in the following way: + +During the execution of handlers at fork time, the atfork lock is +released prior to the execution of each handler and taken again upon its +return. Any handler registrations or de-registrations that occurred +during the execution of the handler are accounted for before proceeding +with further handler execution. + +If a handler that hasn't been executed yet gets de-registered by another +handler during fork, it will not be executed. If a handler gets +registered by another handler during fork, it will not be executed +during that particular fork. + +The possibility that handlers may now be registered or deregistered +during handler execution means that identifying the next handler to be +run after a given handler may register/de-register others requires some +bookkeeping. The fork_handler struct has an additional field, 'id', +which is assigned sequentially during registration. Thus, handlers are +executed in ascending order of 'id' during 'prepare', and descending +order of 'id' during parent/child handler execution after the fork. + +Two tests are included: + +* tst-atfork3: Adhemerval Zanella <adhemerval.zanella@linaro.org> + This test exercises calling dlclose from prepare, parent, and child + handlers. + +* tst-atfork4: This test exercises calling pthread_atfork and dlclose + from the prepare handler. + +[BZ #24595, BZ #27054] + +Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> +Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> +(cherry picked from commit 52a103e237329b9f88a28513fe7506ffc3bd8ced) +--- + include/register-atfork.h | 26 ++++---- + posix/fork.c | 7 +- + posix/register-atfork.c | 140 ++++++++++++++++++++++++++++++--------- + sysdeps/pthread/Makefile | 38 +++++++++-- + sysdeps/pthread/tst-atfork3.c | 118 +++++++++++++++++++++++++++++++++ + sysdeps/pthread/tst-atfork3mod.c | 44 ++++++++++++ + sysdeps/pthread/tst-atfork4.c | 128 +++++++++++++++++++++++++++++++++++ + sysdeps/pthread/tst-atfork4mod.c | 48 ++++++++++++++ + 8 files changed, 499 insertions(+), 50 deletions(-) + create mode 100644 sysdeps/pthread/tst-atfork3.c + create mode 100644 sysdeps/pthread/tst-atfork3mod.c + create mode 100644 sysdeps/pthread/tst-atfork4.c + create mode 100644 sysdeps/pthread/tst-atfork4mod.c + +diff --git a/include/register-atfork.h b/include/register-atfork.h +index fadde14..6d7bfd8 100644 +--- a/include/register-atfork.h ++++ b/include/register-atfork.h +@@ -26,6 +26,7 @@ struct fork_handler + void (*parent_handler) (void); + void (*child_handler) (void); + void *dso_handle; ++ uint64_t id; + }; + + /* Function to call to unregister fork handlers. */ +@@ -39,19 +40,18 @@ enum __run_fork_handler_type + atfork_run_parent + }; + +-/* Run the atfork handlers and lock/unlock the internal lock depending +- of the WHO argument: +- +- - atfork_run_prepare: run all the PREPARE_HANDLER in reverse order of +- insertion and locks the internal lock. +- - atfork_run_child: run all the CHILD_HANDLER and unlocks the internal +- lock. +- - atfork_run_parent: run all the PARENT_HANDLER and unlocks the internal +- lock. +- +- Perform locking only if DO_LOCKING. */ +-extern void __run_fork_handlers (enum __run_fork_handler_type who, +- _Bool do_locking) attribute_hidden; ++/* Run the atfork prepare handlers in the reverse order of registration and ++ return the ID of the last registered handler. If DO_LOCKING is true, the ++ internal lock is held locked upon return. */ ++extern uint64_t __run_prefork_handlers (_Bool do_locking) attribute_hidden; ++ ++/* Given a handler type (parent or child), run all the atfork handlers in ++ the order of registration up to and including the handler with id equal ++ to LASTRUN. If DO_LOCKING is true, the internal lock is unlocked prior ++ to return. */ ++extern void __run_postfork_handlers (enum __run_fork_handler_type who, ++ _Bool do_locking, ++ uint64_t lastrun) attribute_hidden; + + /* C library side function to register new fork handlers. */ + extern int __register_atfork (void (*__prepare) (void), +diff --git a/posix/fork.c b/posix/fork.c +index 021691b..890b806 100644 +--- a/posix/fork.c ++++ b/posix/fork.c +@@ -46,8 +46,9 @@ __libc_fork (void) + best effort to make is async-signal-safe at least for single-thread + case. */ + bool multiple_threads = __libc_single_threaded == 0; ++ uint64_t lastrun; + +- __run_fork_handlers (atfork_run_prepare, multiple_threads); ++ lastrun = __run_prefork_handlers (multiple_threads); + + struct nss_database_data nss_database_data; + +@@ -105,7 +106,7 @@ __libc_fork (void) + reclaim_stacks (); + + /* Run the handlers registered for the child. */ +- __run_fork_handlers (atfork_run_child, multiple_threads); ++ __run_postfork_handlers (atfork_run_child, multiple_threads, lastrun); + } + else + { +@@ -123,7 +124,7 @@ __libc_fork (void) + } + + /* Run the handlers registered for the parent. */ +- __run_fork_handlers (atfork_run_parent, multiple_threads); ++ __run_postfork_handlers (atfork_run_parent, multiple_threads, lastrun); + + if (pid < 0) + __set_errno (save_errno); +diff --git a/posix/register-atfork.c b/posix/register-atfork.c +index 6fd9e4c..6370437 100644 +--- a/posix/register-atfork.c ++++ b/posix/register-atfork.c +@@ -19,6 +19,8 @@ + #include <libc-lock.h> + #include <stdbool.h> + #include <register-atfork.h> ++#include <intprops.h> ++#include <stdio.h> + + #define DYNARRAY_ELEMENT struct fork_handler + #define DYNARRAY_STRUCT fork_handler_list +@@ -27,7 +29,7 @@ + #include <malloc/dynarray-skeleton.c> + + static struct fork_handler_list fork_handlers; +-static bool fork_handler_init = false; ++static uint64_t fork_handler_counter; + + static int atfork_lock = LLL_LOCK_INITIALIZER; + +@@ -37,11 +39,8 @@ __register_atfork (void (*prepare) (void), void (*parent) (void), + { + lll_lock (atfork_lock, LLL_PRIVATE); + +- if (!fork_handler_init) +- { +- fork_handler_list_init (&fork_handlers); +- fork_handler_init = true; +- } ++ if (fork_handler_counter == 0) ++ fork_handler_list_init (&fork_handlers); + + struct fork_handler *newp = fork_handler_list_emplace (&fork_handlers); + if (newp != NULL) +@@ -50,6 +49,13 @@ __register_atfork (void (*prepare) (void), void (*parent) (void), + newp->parent_handler = parent; + newp->child_handler = child; + newp->dso_handle = dso_handle; ++ ++ /* IDs assigned to handlers start at 1 and increment with handler ++ registration. Un-registering a handlers discards the corresponding ++ ID. It is not reused in future registrations. */ ++ if (INT_ADD_OVERFLOW (fork_handler_counter, 1)) ++ __libc_fatal ("fork handler counter overflow"); ++ newp->id = ++fork_handler_counter; + } + + /* Release the lock. */ +@@ -104,37 +110,111 @@ __unregister_atfork (void *dso_handle) + lll_unlock (atfork_lock, LLL_PRIVATE); + } + +-void +-__run_fork_handlers (enum __run_fork_handler_type who, _Bool do_locking) ++uint64_t ++__run_prefork_handlers (_Bool do_locking) + { +- struct fork_handler *runp; ++ uint64_t lastrun; + +- if (who == atfork_run_prepare) ++ if (do_locking) ++ lll_lock (atfork_lock, LLL_PRIVATE); ++ ++ /* We run prepare handlers from last to first. After fork, only ++ handlers up to the last handler found here (pre-fork) will be run. ++ Handlers registered during __run_prefork_handlers or ++ __run_postfork_handlers will be positioned after this last handler, and ++ since their prepare handlers won't be run now, their parent/child ++ handlers should also be ignored. */ ++ lastrun = fork_handler_counter; ++ ++ size_t sl = fork_handler_list_size (&fork_handlers); ++ for (size_t i = sl; i > 0;) + { +- if (do_locking) +- lll_lock (atfork_lock, LLL_PRIVATE); +- size_t sl = fork_handler_list_size (&fork_handlers); +- for (size_t i = sl; i > 0; i--) +- { +- runp = fork_handler_list_at (&fork_handlers, i - 1); +- if (runp->prepare_handler != NULL) +- runp->prepare_handler (); +- } ++ struct fork_handler *runp ++ = fork_handler_list_at (&fork_handlers, i - 1); ++ ++ uint64_t id = runp->id; ++ ++ if (runp->prepare_handler != NULL) ++ { ++ if (do_locking) ++ lll_unlock (atfork_lock, LLL_PRIVATE); ++ ++ runp->prepare_handler (); ++ ++ if (do_locking) ++ lll_lock (atfork_lock, LLL_PRIVATE); ++ } ++ ++ /* We unlocked, ran the handler, and locked again. In the ++ meanwhile, one or more deregistrations could have occurred leading ++ to the current (just run) handler being moved up the list or even ++ removed from the list itself. Since handler IDs are guaranteed to ++ to be in increasing order, the next handler has to have: */ ++ ++ /* A. An earlier position than the current one has. */ ++ i--; ++ ++ /* B. A lower ID than the current one does. The code below skips ++ any newly added handlers with higher IDs. */ ++ while (i > 0 ++ && fork_handler_list_at (&fork_handlers, i - 1)->id >= id) ++ i--; + } +- else ++ ++ return lastrun; ++} ++ ++void ++__run_postfork_handlers (enum __run_fork_handler_type who, _Bool do_locking, ++ uint64_t lastrun) ++{ ++ size_t sl = fork_handler_list_size (&fork_handlers); ++ for (size_t i = 0; i < sl;) + { +- size_t sl = fork_handler_list_size (&fork_handlers); +- for (size_t i = 0; i < sl; i++) +- { +- runp = fork_handler_list_at (&fork_handlers, i); +- if (who == atfork_run_child && runp->child_handler) +- runp->child_handler (); +- else if (who == atfork_run_parent && runp->parent_handler) +- runp->parent_handler (); +- } ++ struct fork_handler *runp = fork_handler_list_at (&fork_handlers, i); ++ uint64_t id = runp->id; ++ ++ /* prepare handlers were not run for handlers with ID > LASTRUN. ++ Thus, parent/child handlers will also not be run. */ ++ if (id > lastrun) ++ break; ++ + if (do_locking) +- lll_unlock (atfork_lock, LLL_PRIVATE); ++ lll_unlock (atfork_lock, LLL_PRIVATE); ++ ++ if (who == atfork_run_child && runp->child_handler) ++ runp->child_handler (); ++ else if (who == atfork_run_parent && runp->parent_handler) ++ runp->parent_handler (); ++ ++ if (do_locking) ++ lll_lock (atfork_lock, LLL_PRIVATE); ++ ++ /* We unlocked, ran the handler, and locked again. In the meanwhile, ++ one or more [de]registrations could have occurred. Due to this, ++ the list size must be updated. */ ++ sl = fork_handler_list_size (&fork_handlers); ++ ++ /* The just-run handler could also have moved up the list. */ ++ ++ if (sl > i && fork_handler_list_at (&fork_handlers, i)->id == id) ++ /* The position of the recently run handler hasn't changed. The ++ next handler to be run is an easy increment away. */ ++ i++; ++ else ++ { ++ /* The next handler to be run is the first handler in the list ++ to have an ID higher than the current one. */ ++ for (i = 0; i < sl; i++) ++ { ++ if (fork_handler_list_at (&fork_handlers, i)->id > id) ++ break; ++ } ++ } + } ++ ++ if (do_locking) ++ lll_unlock (atfork_lock, LLL_PRIVATE); + } + + +diff --git a/sysdeps/pthread/Makefile b/sysdeps/pthread/Makefile +index 00419c4..5147588 100644 +--- a/sysdeps/pthread/Makefile ++++ b/sysdeps/pthread/Makefile +@@ -154,16 +154,36 @@ tests += tst-cancelx2 tst-cancelx3 tst-cancelx6 tst-cancelx8 tst-cancelx9 \ + tst-cleanupx0 tst-cleanupx1 tst-cleanupx2 tst-cleanupx3 + + ifeq ($(build-shared),yes) +-tests += tst-atfork2 tst-pt-tls4 tst-_res1 tst-fini1 tst-create1 ++tests += \ ++ tst-atfork2 \ ++ tst-pt-tls4 \ ++ tst-_res1 \ ++ tst-fini1 \ ++ tst-create1 \ ++ tst-atfork3 \ ++ tst-atfork4 \ ++# tests ++ + tests-nolibpthread += tst-fini1 + endif + +-modules-names += tst-atfork2mod tst-tls4moda tst-tls4modb \ +- tst-_res1mod1 tst-_res1mod2 tst-fini1mod \ +- tst-create1mod ++modules-names += \ ++ tst-atfork2mod \ ++ tst-tls4moda \ ++ tst-tls4modb \ ++ tst-_res1mod1 \ ++ tst-_res1mod2 \ ++ tst-fini1mod \ ++ tst-create1mod \ ++ tst-atfork3mod \ ++ tst-atfork4mod \ ++# module-names ++ + test-modules = $(addprefix $(objpfx),$(addsuffix .so,$(modules-names))) + + tst-atfork2mod.so-no-z-defs = yes ++tst-atfork3mod.so-no-z-defs = yes ++tst-atfork4mod.so-no-z-defs = yes + tst-create1mod.so-no-z-defs = yes + + ifeq ($(build-shared),yes) +@@ -226,8 +246,18 @@ tst-atfork2-ENV = MALLOC_TRACE=$(objpfx)tst-atfork2.mtrace \ + LD_PRELOAD=$(common-objpfx)/malloc/libc_malloc_debug.so + $(objpfx)tst-atfork2mod.so: $(shared-thread-library) + ++$(objpfx)tst-atfork3: $(shared-thread-library) ++LDFLAGS-tst-atfork3 = -rdynamic ++$(objpfx)tst-atfork3mod.so: $(shared-thread-library) ++ ++$(objpfx)tst-atfork4: $(shared-thread-library) ++LDFLAGS-tst-atfork4 = -rdynamic ++$(objpfx)tst-atfork4mod.so: $(shared-thread-library) ++ + ifeq ($(build-shared),yes) + $(objpfx)tst-atfork2.out: $(objpfx)tst-atfork2mod.so ++$(objpfx)tst-atfork3.out: $(objpfx)tst-atfork3mod.so ++$(objpfx)tst-atfork4.out: $(objpfx)tst-atfork4mod.so + endif + + ifeq ($(build-shared),yes) +diff --git a/sysdeps/pthread/tst-atfork3.c b/sysdeps/pthread/tst-atfork3.c +new file mode 100644 +index 0000000..bb2250e +--- /dev/null ++++ b/sysdeps/pthread/tst-atfork3.c +@@ -0,0 +1,118 @@ ++/* Check if pthread_atfork handler can call dlclose (BZ#24595). ++ Copyright (C) 2022 Free Software Foundation, Inc. ++ This file is part of the GNU C Library. ++ ++ The GNU C Library is free software; you can redistribute it and/or ++ modify it under the terms of the GNU Lesser General Public ++ License as published by the Free Software Foundation; either ++ version 2.1 of the License, or (at your option) any later version. ++ ++ The GNU C Library is distributed in the hope that it will be useful, ++ but WITHOUT ANY WARRANTY; without even the implied warranty of ++ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ++ Lesser General Public License for more details. ++ ++ You should have received a copy of the GNU Lesser General Public ++ License along with the GNU C Library; if not, see ++ <http://www.gnu.org/licenses/>. */ ++ ++#include <stdio.h> ++#include <pthread.h> ++#include <unistd.h> ++#include <stdlib.h> ++#include <stdbool.h> ++ ++#include <support/check.h> ++#include <support/xthread.h> ++#include <support/capture_subprocess.h> ++#include <support/xdlfcn.h> ++ ++/* Check if pthread_atfork handlers do not deadlock when calling a function ++ that might alter the internal fork handle list, such as dlclose. ++ ++ The test registers a callback set with pthread_atfork(), dlopen() a shared ++ library (nptl/tst-atfork3mod.c), calls an exported symbol from the library ++ (which in turn also registers atfork handlers), and calls fork to trigger ++ the callbacks. */ ++ ++static void *handler; ++static bool run_dlclose_prepare; ++static bool run_dlclose_parent; ++static bool run_dlclose_child; ++ ++static void ++prepare (void) ++{ ++ if (run_dlclose_prepare) ++ xdlclose (handler); ++} ++ ++static void ++parent (void) ++{ ++ if (run_dlclose_parent) ++ xdlclose (handler); ++} ++ ++static void ++child (void) ++{ ++ if (run_dlclose_child) ++ xdlclose (handler); ++} ++ ++static void ++proc_func (void *closure) ++{ ++} ++ ++static void ++do_test_generic (bool dlclose_prepare, bool dlclose_parent, bool dlclose_child) ++{ ++ run_dlclose_prepare = dlclose_prepare; ++ run_dlclose_parent = dlclose_parent; ++ run_dlclose_child = dlclose_child; ++ ++ handler = xdlopen ("tst-atfork3mod.so", RTLD_NOW); ++ ++ int (*atfork3mod_func)(void); ++ atfork3mod_func = xdlsym (handler, "atfork3mod_func"); ++ ++ atfork3mod_func (); ++ ++ struct support_capture_subprocess proc ++ = support_capture_subprocess (proc_func, NULL); ++ support_capture_subprocess_check (&proc, "tst-atfork3", 0, sc_allow_none); ++ ++ handler = atfork3mod_func = NULL; ++ ++ support_capture_subprocess_free (&proc); ++} ++ ++static void * ++thread_func (void *closure) ++{ ++ return NULL; ++} ++ ++static int ++do_test (void) ++{ ++ { ++ /* Make the process acts as multithread. */ ++ pthread_attr_t attr; ++ xpthread_attr_init (&attr); ++ xpthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED); ++ xpthread_create (&attr, thread_func, NULL); ++ } ++ ++ TEST_COMPARE (pthread_atfork (prepare, parent, child), 0); ++ ++ do_test_generic (true /* prepare */, false /* parent */, false /* child */); ++ do_test_generic (false /* prepare */, true /* parent */, false /* child */); ++ do_test_generic (false /* prepare */, false /* parent */, true /* child */); ++ ++ return 0; ++} ++ ++#include <support/test-driver.c> +diff --git a/sysdeps/pthread/tst-atfork3mod.c b/sysdeps/pthread/tst-atfork3mod.c +new file mode 100644 +index 0000000..6d0658c +--- /dev/null ++++ b/sysdeps/pthread/tst-atfork3mod.c +@@ -0,0 +1,44 @@ ++/* Copyright (C) 2022 Free Software Foundation, Inc. ++ This file is part of the GNU C Library. ++ ++ The GNU C Library is free software; you can redistribute it and/or ++ modify it under the terms of the GNU Lesser General Public ++ License as published by the Free Software Foundation; either ++ version 2.1 of the License, or (at your option) any later version. ++ ++ The GNU C Library is distributed in the hope that it will be useful, ++ but WITHOUT ANY WARRANTY; without even the implied warranty of ++ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ++ Lesser General Public License for more details. ++ ++ You should have received a copy of the GNU Lesser General Public ++ License along with the GNU C Library; if not, see ++ <http://www.gnu.org/licenses/>. */ ++ ++#include <unistd.h> ++#include <stdlib.h> ++#include <pthread.h> ++ ++#include <support/check.h> ++ ++static void ++mod_prepare (void) ++{ ++} ++ ++static void ++mod_parent (void) ++{ ++} ++ ++static void ++mod_child (void) ++{ ++} ++ ++int atfork3mod_func (void) ++{ ++ TEST_COMPARE (pthread_atfork (mod_prepare, mod_parent, mod_child), 0); ++ ++ return 0; ++} +diff --git a/sysdeps/pthread/tst-atfork4.c b/sysdeps/pthread/tst-atfork4.c +new file mode 100644 +index 0000000..52dc87e +--- /dev/null ++++ b/sysdeps/pthread/tst-atfork4.c +@@ -0,0 +1,128 @@ ++/* pthread_atfork supports handlers that call pthread_atfork or dlclose. ++ Copyright (C) 2022 Free Software Foundation, Inc. ++ This file is part of the GNU C Library. ++ ++ The GNU C Library is free software; you can redistribute it and/or ++ modify it under the terms of the GNU Lesser General Public ++ License as published by the Free Software Foundation; either ++ version 2.1 of the License, or (at your option) any later version. ++ ++ The GNU C Library is distributed in the hope that it will be useful, ++ but WITHOUT ANY WARRANTY; without even the implied warranty of ++ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ++ Lesser General Public License for more details. ++ ++ You should have received a copy of the GNU Lesser General Public ++ License along with the GNU C Library; if not, see ++ <https://www.gnu.org/licenses/>. */ ++ ++#include <support/xdlfcn.h> ++#include <stdio.h> ++#include <support/xthread.h> ++#include <sys/types.h> ++#include <sys/wait.h> ++#include <support/xunistd.h> ++#include <support/check.h> ++#include <stdlib.h> ++ ++static void * ++thread_func (void *x) ++{ ++ return NULL; ++} ++ ++static unsigned int second_atfork_handler_runcount = 0; ++ ++static void ++second_atfork_handler (void) ++{ ++ second_atfork_handler_runcount++; ++} ++ ++static void *h = NULL; ++ ++static unsigned int atfork_handler_runcount = 0; ++ ++static void ++prepare (void) ++{ ++ /* These atfork handlers are registered while atfork handlers are being ++ executed and thus will not be executed during the corresponding ++ fork. */ ++ TEST_VERIFY_EXIT (pthread_atfork (second_atfork_handler, ++ second_atfork_handler, ++ second_atfork_handler) == 0); ++ ++ /* This will de-register the atfork handlers registered by the dlopen'd ++ library and so they will not be executed. */ ++ if (h != NULL) ++ { ++ xdlclose (h); ++ h = NULL; ++ } ++ ++ atfork_handler_runcount++; ++} ++ ++static void ++after (void) ++{ ++ atfork_handler_runcount++; ++} ++ ++static int ++do_test (void) ++{ ++ /* Make sure __libc_single_threaded is 0. */ ++ pthread_attr_t attr; ++ xpthread_attr_init (&attr); ++ xpthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED); ++ xpthread_create (&attr, thread_func, NULL); ++ ++ void (*reg_atfork_handlers) (void); ++ ++ h = xdlopen ("tst-atfork4mod.so", RTLD_LAZY); ++ ++ reg_atfork_handlers = xdlsym (h, "reg_atfork_handlers"); ++ ++ reg_atfork_handlers (); ++ ++ /* We register our atfork handlers *after* loading the module so that our ++ prepare handler is called first at fork, where we then dlclose the ++ module before its prepare handler has a chance to be called. */ ++ TEST_VERIFY_EXIT (pthread_atfork (prepare, after, after) == 0); ++ ++ pid_t pid = xfork (); ++ ++ /* Both the parent and the child processes should observe this. */ ++ TEST_VERIFY_EXIT (atfork_handler_runcount == 2); ++ TEST_VERIFY_EXIT (second_atfork_handler_runcount == 0); ++ ++ if (pid > 0) ++ { ++ int childstat; ++ ++ xwaitpid (-1, &childstat, 0); ++ TEST_VERIFY_EXIT (WIFEXITED (childstat) ++ && WEXITSTATUS (childstat) == 0); ++ ++ /* This time, the second set of atfork handlers should also be called ++ since the handlers are already in place before fork is called. */ ++ ++ pid = xfork (); ++ ++ TEST_VERIFY_EXIT (atfork_handler_runcount == 4); ++ TEST_VERIFY_EXIT (second_atfork_handler_runcount == 2); ++ ++ if (pid > 0) ++ { ++ xwaitpid (-1, &childstat, 0); ++ TEST_VERIFY_EXIT (WIFEXITED (childstat) ++ && WEXITSTATUS (childstat) == 0); ++ } ++ } ++ ++ return 0; ++} ++ ++#include <support/test-driver.c> +diff --git a/sysdeps/pthread/tst-atfork4mod.c b/sysdeps/pthread/tst-atfork4mod.c +new file mode 100644 +index 0000000..e111efe +--- /dev/null ++++ b/sysdeps/pthread/tst-atfork4mod.c +@@ -0,0 +1,48 @@ ++/* pthread_atfork supports handlers that call pthread_atfork or dlclose. ++ Copyright (C) 2022 Free Software Foundation, Inc. ++ This file is part of the GNU C Library. ++ ++ The GNU C Library is free software; you can redistribute it and/or ++ modify it under the terms of the GNU Lesser General Public ++ License as published by the Free Software Foundation; either ++ version 2.1 of the License, or (at your option) any later version. ++ ++ The GNU C Library is distributed in the hope that it will be useful, ++ but WITHOUT ANY WARRANTY; without even the implied warranty of ++ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ++ Lesser General Public License for more details. ++ ++ You should have received a copy of the GNU Lesser General Public ++ License along with the GNU C Library; if not, see ++ <https://www.gnu.org/licenses/>. */ ++ ++#include <pthread.h> ++#include <stdlib.h> ++ ++/* This dynamically loaded library simply registers its atfork handlers when ++ asked to. The atfork handlers should never be executed because the ++ library is unloaded before fork is called by the test program. */ ++ ++static void ++prepare (void) ++{ ++ abort (); ++} ++ ++static void ++parent (void) ++{ ++ abort (); ++} ++ ++static void ++child (void) ++{ ++ abort (); ++} ++ ++void ++reg_atfork_handlers (void) ++{ ++ pthread_atfork (prepare, parent, child); ++} +-- +1.8.3.1 + |