glibc/include
Arjun Shankar 52a103e237 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>
2022-05-25 11:27:31 +02:00
..
arpa resolv: Move ns_samename into its own file, and into libc 2021-07-19 07:56:21 +02:00
bits Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
gnu Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
net
netinet nss_files: Consolidate line parse declarations in <nss_files.h> 2020-07-21 07:33:20 +02:00
programs Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
protocols
rpc Handle out-of-memory case in svc_tcp.c/svc_unix.c:rendezvous_request. 2020-12-10 11:11:20 +01:00
rpcsvc Remove --enable-obsolete-nsl configure flag 2020-07-08 17:25:57 +02:00
sys Linux: Only generate 64 bit timestamps for 64 bit time_t recvmsg/recvmmsg 2022-01-28 18:18:27 -03:00
aio.h Linux: Move aio_suspend, aio_suspend64, __aio_suspend_time64 to libc 2021-06-25 11:55:27 +02:00
aliases.h Remove --enable-obsolete-nsl configure flag 2020-07-08 17:25:57 +02:00
alloc_buffer.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
alloca.h Remove macros extend_alloca, extend_alloca_account [BZ #18023] 2018-06-27 19:20:37 +02:00
allocate_once.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
ar.h Add missing header wrappers under include/ 2019-02-16 08:25:16 +01:00
argp-fmtstream.h Mark internal argp functions with attribute_hidden [BZ #18822] 2017-10-01 15:10:27 -07:00
argp.h ldbl-opt: Add argp_error and argp_failure (bug 23983) 2019-03-01 15:21:32 -03:00
argz.h Use libc_hidden_* for argz_next, __argz_next (bug 15105). 2018-02-15 21:00:02 +00:00
array_length.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
assert.h Introduce NO_RTLD_HIDDEN, make hurd use it instead of NO_HIDDEN 2017-10-03 01:33:38 +02:00
atomic_wide_counter.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
atomic.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
byteswap.h
clone_internal.h Add an internal wrapper for clone, clone2 and clone3 2021-07-14 06:33:58 -07:00
complex.h float128: Add private _Float128 declarations for libm. 2017-05-15 10:23:28 -03:00
cpio.h
crypt.h Add include/crypt.h. 2016-10-28 22:40:16 -04:00
ctype.h Use libc_hidden_* for tolower, toupper (bug 15105). 2018-02-23 13:54:53 +00:00
des.h
dirent.h Use 64 bit time_t stat internally 2021-06-22 12:09:52 -03:00
dlfcn.h elf: Add _dl_find_object function 2021-12-28 22:52:56 +01:00
dso_handle.h Mark __dso_handle as hidden [BZ #18822] 2017-09-26 16:53:44 -07:00
elf.h elf: Refuse to dlopen PIE objects [BZ #24323] 2019-06-18 16:42:10 +02:00
endian.h
envz.h Installed header hygiene (BZ#20366): Test of installed headers. 2016-09-23 08:43:56 -04:00
err.h ldbl-128ibm-compat: PLT redirects for using ldbl redirects internally 2020-03-25 14:34:23 -05:00
errno.h Remove tls.h inclusion from internal errno.h 2020-11-13 12:59:19 -03:00
error.h ldbl-opt: Add error and error_at_line (bug 23984) 2019-03-01 15:26:36 -03:00
execinfo.h Installed header hygiene (BZ#20366): Test of installed headers. 2016-09-23 08:43:56 -04:00
fcntl.h Fix Linux fcntl OFD locks for non-LFS architectures (BZ#20251) 2018-06-26 13:22:53 -03:00
features-time64.h y2038: Add support for 64-bit time on legacy ABIs 2021-06-15 10:42:11 -03:00
features.h Prepare for glibc 2.35 release. 2022-02-03 00:23:26 -05:00
fenv.h Move fenv.h soft-float inlines from fenv_private.h to include/fenv.h. 2018-09-04 19:52:06 +00:00
file_change_detection.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
filename.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
float.h Make totalorder and totalordermag functions take pointer arguments. 2019-08-15 15:18:34 +00:00
fmtmsg.h
fnmatch.h
fpu_control.h Hide internal __setfpucw function [BZ #18822] 2017-10-01 17:52:15 -07:00
fstab.h Add missing header wrappers under include/ 2019-02-16 08:25:16 +01:00
fts.h io: Add fts64 with 64-bit time_t support 2021-06-15 10:42:11 -03:00
ftw.h io: Add ftw64 with 64-bit time_t support 2021-06-15 10:42:11 -03:00
gconv.h
getopt_int.h
getopt.h getopt: remove USE_NONOPTION_FLAGS 2017-04-07 07:45:53 -04:00
glob.h Fix extra PLT reference in libc.so due to __glob64_time64 if build with gcc 7.5 on 32bit. 2021-07-01 16:46:59 +02:00
gmp.h Mark internal gmp functions with attribute_hidden [BZ #18822] 2017-10-01 15:15:30 -07:00
gnu-versions.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
grp-merge.h
grp.h nss_files: Consolidate line parse declarations in <nss_files.h> 2020-07-21 07:33:20 +02:00
gshadow.h nss_files: Consolidate line parse declarations in <nss_files.h> 2020-07-21 07:33:20 +02:00
iconv.h
idx.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
ifaddrs.h hurd: Fix getifaddrs' and freeifaddrs' symbol exposition 2017-09-28 01:05:18 +02:00
ifreq.h Hide internal __ifreq function [BZ #18822] 2017-10-01 17:35:46 -07:00
ifunc-impl-list.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
inline-hashtab.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
intprops.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
inttypes.h Make strtoimax, strtoumax, wcstoimax, wcstoumax into aliases 2020-12-08 18:15:27 +00:00
langinfo.h
lastlog.h Add missing header wrappers under include/ 2019-02-16 08:25:16 +01:00
libc-diag.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
libc-internal.h elf: Remove __libc_init_secure 2022-04-19 15:52:27 -07:00
libc-pointer-arith.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
libc-symbols.h Add declare_object_symbol_alias for assembly codes (BZ #28128) 2022-05-13 10:54:41 -03:00
libgen.h
libintl.h Document the internal _ and N_ macros 2020-05-06 17:35:40 +02:00
limits.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
link.h Add GLIBC_ABI_DT_RELR for DT_RELR support 2022-04-26 10:16:11 -07:00
list_t.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
list.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
locale.h
loop_unroll.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
malloc.h Simplify __malloc_initialized 2021-07-22 18:38:04 +05:30
math-narrow-eval.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
math.h Redirect fma calls to __fma in libm 2021-09-15 22:57:35 +00:00
mcheck.h mcheck: Wean away from malloc hooks [BZ #23489] 2021-07-22 18:38:02 +05:30
memory.h
mntent.h Hide internal __hasmntopt function [BZ #18822] 2017-10-01 17:37:42 -07:00
monetary.h Rename __LONG_DOUBLE_USES_FLOAT128 to __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI 2020-04-30 08:52:08 -05:00
mqueue.h Linux: Move mq_send, mq_timedsend, __mq_timedsend_time64 to libc 2021-06-25 12:21:12 +02:00
netdb.h nss_files: Move into libc 2021-07-07 18:33:52 +02:00
netgroup.h
nl_types.h
nss_dns.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
nss_files.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
nss.h nss: Export nscd hash function as __nss_hash [BZ #22459] 2017-11-23 14:08:11 +01:00
nsswitch.h
obstack.h Installed header hygiene (BZ#20366): Test of installed headers. 2016-09-23 08:43:56 -04:00
plural-exp.h Hide internal __gettextparse function [BZ #18822] 2017-10-01 17:31:05 -07:00
poll.h
printf.h stdio-common: Move union printf_arg int <printf.h> 2022-05-24 08:03:11 +02:00
pthread.h Linux: Move mq_notify from librt to libc 2021-06-25 12:20:47 +02:00
pty.h login: Move libutil into libc 2021-06-30 08:43:37 +02:00
pwd.h nss_files: Consolidate line parse declarations in <nss_files.h> 2020-07-21 07:33:20 +02:00
random-bits.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
re_comp.h Add missing header wrappers under include/ 2019-02-16 08:25:16 +01:00
regex.h regex: copy back from Gnulib 2021-09-21 08:00:44 -07:00
regexp.h Add missing header wrappers under include/ 2019-02-16 08:25:16 +01:00
register-atfork.h Fix deadlock when pthread_atfork handler calls pthread_atfork or dlclose 2022-05-25 11:27:31 +02:00
resolv.h resolv: Move res_queriesmatch to its own file and into libc 2021-07-19 07:56:21 +02:00
rounding-mode.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
rtld-malloc.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
sched.h Add hidden prototypes for __sched_getparam, __sched_getscheduler 2020-02-20 08:57:01 +01:00
scratch_buffer.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
search.h misc: Add twalk_r function 2019-05-02 11:42:51 +02:00
set-hooks.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
setjmp.h setjmp: Replace jmp_buf-macros.h with jmp_buf-macros.sym 2021-11-22 13:43:22 -03:00
sgtty.h
shadow.h nss_files: Consolidate line parse declarations in <nss_files.h> 2020-07-21 07:33:20 +02:00
shlib-compat.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
shm-directory.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
signal.h stdio: Remove the usage of $(fno-unit-at-a-time) for siglist.c 2022-05-13 10:54:41 -03:00
spawn.h posix: Use posix_spawn for wordexp 2019-10-09 17:48:41 -03:00
stab.h
stackinfo.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
stap-probe.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
stdc-predef.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
stdint.h Move inttypes.h and stdint.h to stdlib. 2019-03-13 09:42:09 -04:00
stdio_ext.h Installed header hygiene (BZ#20366): Test of installed headers. 2016-09-23 08:43:56 -04:00
stdio.h stdio: Remove the usage of $(fno-unit-at-a-time) for errlist.c 2022-05-13 10:54:41 -03:00
stdlib.h Remove __morecore and __default_morecore 2021-07-22 18:37:57 +05:30
string.h String: Add hidden defs for __memcmpeq() to enable internal usage 2021-10-26 16:51:29 -05:00
strings.h
struct___timeb64.h time: Add 64-bit time_t support for ftime 2020-10-27 09:54:50 -03:00
struct___timespec64.h y2038: include: Move struct __timespec64 definition to a separate file 2020-04-06 23:05:11 +02:00
struct___timeval64.h y2038: include: Move struct __timeval64 definition to a separate file 2020-05-05 19:36:25 +02:00
stubs-prologue.h
syscall.h
sysexits.h
syslog.h
tar.h
termios.h Hide internal __tcgetattr function [BZ #18822] 2017-10-01 17:48:24 -07:00
tgmath.h
time.h clock_settime/clock_gettime: Use __nonnull to avoid null pointer 2022-05-05 17:48:04 +05:30
ttyent.h Installed header hygiene (BZ#20366): Test of installed headers. 2016-09-23 08:43:56 -04:00
uchar.h
ucontext.h
ulimit.h
unistd.h elf: Remove __libc_init_secure 2022-04-19 15:52:27 -07:00
utime.h
utmp.h login: Move libutil into libc 2021-06-30 08:43:37 +02:00
values.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
verify.h posix: Sync regex with gnulib 2019-11-06 09:20:52 -03:00
wait.h Add missing header wrappers under include/ 2019-02-16 08:25:16 +01:00
wchar.h wcrtomb: Make behavior POSIX compliant 2022-05-13 19:15:46 +05:30
wctype.h Remove __need macros from stdio.h and wchar.h. 2017-06-08 13:58:17 -04:00
wordexp.h