glibc/stdlib/Makefile
Siddhesh Poyarekar 90b37cac8b Also use l_tls_dtor_count to decide on object unload (BZ #18657)
When an TLS destructor is registered, we set the DF_1_NODELETE flag to
signal that the object should not be destroyed.  We then clear the
DF_1_NODELETE flag when all destructors are called, which is wrong -
the flag could have been set by other means too.

This patch replaces this use of the flag by using l_tls_dtor_count
directly to determine whether it is safe to unload the object.  This
change has the added advantage of eliminating the lock taking when
calling the destructors, which could result in a deadlock.  The patch
also fixes the test case tst-tls-atexit - it was making an invalid
dlclose call, which would just return an error silently.

I have also added a detailed note on concurrency which also aims to
justify why I chose the semantics I chose for accesses to
l_tls_dtor_count.  Thanks to Torvald for his help in getting me
started on this and (literally) teaching my how to approach the
problem.

Change verified on x86_64; the test suite does not show any
regressions due to the patch.

ChangeLog:

	[BZ #18657]
	* elf/dl-close.c (_dl_close_worker): Don't unload DSO if there
	are pending TLS destructor calls.
	* include/link.h (struct link_map): Add concurrency note for
	L_TLS_DTOR_COUNT.
	* stdlib/cxa_thread_atexit_impl.c (__cxa_thread_atexit_impl):
	Don't touch the link map flag.  Atomically increment
	l_tls_dtor_count.
	(__call_tls_dtors): Atomically decrement l_tls_dtor_count.
	Avoid taking the load lock and don't touch the link map flag.
	* stdlib/tst-tls-atexit-nodelete.c: New test case.
	* stdlib/Makefile (tests): Use it.
	* stdlib/tst-tls-atexit.c (do_test): dlopen
	tst-tls-atexit-lib.so again before dlclose.  Add conditionals
	to allow tst-tls-atexit-nodelete test case to use it.
2015-07-23 11:16:18 +05:30

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6.0 KiB
Makefile

# Copyright (C) 1991-2015 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/>.
#
# Makefile for stdlib routines
#
subdir := stdlib
include ../Makeconfig
headers := stdlib.h bits/stdlib.h bits/stdlib-ldbl.h bits/stdlib-float.h \
monetary.h bits/monetary-ldbl.h \
inttypes.h stdint.h bits/wordsize.h \
errno.h sys/errno.h bits/errno.h \
ucontext.h sys/ucontext.h \
alloca.h fmtmsg.h \
bits/stdlib-bsearch.h
routines := \
atof atoi atol atoll \
abort \
bsearch qsort msort \
getenv putenv setenv secure-getenv \
exit on_exit atexit cxa_atexit cxa_finalize old_atexit \
quick_exit at_quick_exit cxa_at_quick_exit cxa_thread_atexit_impl \
abs labs llabs \
div ldiv lldiv \
mblen mbstowcs mbtowc wcstombs wctomb \
random random_r rand rand_r \
drand48 erand48 lrand48 nrand48 mrand48 jrand48 \
srand48 seed48 lcong48 \
drand48_r erand48_r lrand48_r nrand48_r mrand48_r jrand48_r \
srand48_r seed48_r lcong48_r \
drand48-iter \
strtol strtoul strtoll strtoull \
strtol_l strtoul_l strtoll_l strtoull_l \
strtof strtod strtold \
strtof_l strtod_l strtold_l \
system canonicalize \
a64l l64a \
rpmatch strfmon strfmon_l getsubopt xpg_basename fmtmsg \
strtoimax strtoumax wcstoimax wcstoumax \
getcontext setcontext makecontext swapcontext
aux = grouping groupingwc tens_in_limb
# These routines will be omitted from the libc shared object.
# Instead the static object files will be included in a special archive
# linked against when the shared library will be used.
static-only-routines = atexit at_quick_exit
test-srcs := tst-fmtmsg
tests := tst-strtol tst-strtod testmb testrand testsort testdiv \
test-canon test-canon2 tst-strtoll tst-environ \
tst-xpg-basename tst-random tst-random2 tst-bsearch \
tst-limits tst-rand48 bug-strtod tst-setcontext \
tst-setcontext2 test-a64l tst-qsort tst-system testmb2 \
bug-strtod2 tst-atof1 tst-atof2 tst-strtod2 tst-strtod3 \
tst-rand48-2 tst-makecontext tst-strtod4 tst-strtod5 \
tst-qsort2 tst-makecontext2 tst-strtod6 tst-unsetenv1 \
tst-makecontext3 bug-getcontext bug-fmtmsg1 \
tst-secure-getenv tst-strtod-overflow tst-strtod-round \
tst-tininess tst-strtod-underflow tst-tls-atexit \
tst-setcontext3 tst-tls-atexit-nodelete
tests-static := tst-secure-getenv
modules-names = tst-tls-atexit-lib
ifeq ($(build-shared),yes)
tests += tst-putenv
endif
# Several mpn functions from GNU MP are used by the strtod function.
mpn-routines := inlines add_n addmul_1 cmp divmod_1 divrem udiv_qrnnd \
lshift rshift mod_1 mul mul_1 mul_n sub_n submul_1
mpn-headers = longlong.h gmp.h gmp-impl.h gmp-mparam.h asm-syntax.h
routines := $(strip $(routines) $(mpn-routines)) \
dbl2mpn ldbl2mpn \
mpn2flt mpn2dbl mpn2ldbl
aux += fpioconst mp_clz_tab
tests-extras += tst-putenvmod
extra-test-objs += tst-putenvmod.os
generated += isomac isomac.out tst-putenvmod.so
CFLAGS-bsearch.c = $(uses-callbacks)
CFLAGS-msort.c = $(uses-callbacks)
CFLAGS-qsort.c = $(uses-callbacks)
CFLAGS-system.c = -fexceptions
CFLAGS-system.os = -fomit-frame-pointer
CFLAGS-fmtmsg.c = -fexceptions
CFLAGS-strfmon.c = $(libio-mtsafe)
CFLAGS-strfmon_l.c = $(libio-mtsafe)
CFLAGS-tst-bsearch.c = $(stack-align-test-flags)
CFLAGS-tst-qsort.c = $(stack-align-test-flags)
CFLAGS-tst-makecontext2.c = $(stack-align-test-flags)
# Run a test on the header files we use.
tests-special += $(objpfx)isomac.out
ifeq ($(run-built-tests),yes)
tests-special += $(objpfx)tst-fmtmsg.out
endif
include ../Rules
# Testdir has to be named stdlib and needs to be writable
test-canon-ARGS = --test-dir=${common-objpfx}stdlib
bug-fmtmsg1-ENV = SEV_LEVEL=foo,11,newsev
$(objpfx)isomac.out: $(objpfx)isomac
$(dir $<)$(notdir $<) '$(CC)' \
'-I../include $(+sysdep-includes) $(sysincludes) -I..' > $<.out; \
$(evaluate-test)
isomac-CFLAGS = -O
$(objpfx)isomac: isomac.c
$(native-compile)
$(objpfx)tst-fmtmsg.out: tst-fmtmsg.sh $(objpfx)tst-fmtmsg
$(SHELL) $< $(common-objpfx) '$(test-program-prefix-before-env)' \
'$(run-program-env)' '$(test-program-prefix-after-env)' \
$(common-objpfx)stdlib/; \
$(evaluate-test)
$(objpfx)tst-putenv: $(objpfx)tst-putenvmod.so
LDFLAGS-tst-putenv = $(no-as-needed)
$(objpfx)tst-putenvmod.so: $(objpfx)tst-putenvmod.os $(link-libc-deps)
$(build-module)
libof-tst-putenvmod = extramodules
$(objpfx)bug-getcontext: $(libm)
$(objpfx)tst-strtod-round: $(libm)
$(objpfx)tst-tininess: $(libm)
$(objpfx)tst-strtod-underflow: $(libm)
$(objpfx)tst-strtod6: $(libm)
tst-tls-atexit-lib.so-no-z-defs = yes
$(objpfx)tst-tls-atexit: $(shared-thread-library) $(libdl)
$(objpfx)tst-tls-atexit.out: $(objpfx)tst-tls-atexit-lib.so
$(objpfx)tst-tls-atexit-nodelete: $(shared-thread-library) $(libdl)
$(objpfx)tst-tls-atexit-nodelete.out: $(objpfx)tst-tls-atexit-lib.so
$(objpfx)tst-setcontext3.out: tst-setcontext3.sh $(objpfx)tst-setcontext3
$(SHELL) $< $(common-objpfx) '$(test-program-prefix-before-env)' \
'$(run-program-env)' '$(test-program-prefix-after-env)' \
$(common-objpfx)stdlib/; \
$(evaluate-test)
$(objpfx)tst-makecontext: $(libdl)