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glibc.8240
malloc-Fix-attached-thread-reference-count-hand...
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File malloc-Fix-attached-thread-reference-count-handling-.patch of Package glibc.8240
2015-12-16 Florian Weimer <fweimer@redhat.com> [BZ #19243] * malloc/arena.c (get_free_list): Remove assert and adjust reference count handling. Add comment about reused_arena interaction. (reused_arena): Add comments abount get_free_list interaction. * malloc/tst-malloc-thread-exit.c: New file. * malloc/Makefile (tests): Add tst-malloc-thread-exit. (tst-malloc-thread-exit): Link against libpthread. Index: glibc-2.22/malloc/Makefile =================================================================== --- glibc-2.22.orig/malloc/Makefile +++ glibc-2.22/malloc/Makefile @@ -28,7 +28,7 @@ tests := mallocbug tst-malloc tst-valloc tst-mallocstate tst-mcheck tst-mallocfork tst-trim1 \ tst-malloc-usable tst-realloc tst-posix_memalign \ tst-pvalloc tst-memalign tst-mallopt tst-scratch_buffer \ - tst-malloc-backtrace + tst-malloc-backtrace tst-malloc-thread-exit test-srcs = tst-mtrace routines = malloc morecore mcheck mtrace obstack \ @@ -47,6 +47,8 @@ libmemusage-inhibit-o = $(filter-out .os $(objpfx)tst-malloc-backtrace: $(common-objpfx)nptl/libpthread.so \ $(common-objpfx)nptl/libpthread_nonshared.a +$(objpfx)tst-malloc-thread-exit: $(common-objpfx)nptl/libpthread.so \ + $(common-objpfx)nptl/libpthread_nonshared.a # These should be removed by `make clean'. extra-objs = mcheck-init.o libmcheck.a Index: glibc-2.22/malloc/arena.c =================================================================== --- glibc-2.22.orig/malloc/arena.c +++ glibc-2.22/malloc/arena.c @@ -806,6 +806,8 @@ _int_new_arena (size_t size) } +/* Remove an arena from free_list. The arena may be in use because it + was attached concurrently to a thread by reused_arena below. */ static mstate get_free_list (void) { @@ -820,10 +822,8 @@ get_free_list (void) { free_list = result->next_free; - /* Arenas on the free list are not attached to any thread. */ - assert (result->attached_threads == 0); - /* But the arena will now be attached to this thread. */ - result->attached_threads = 1; + /* The arena will be attached to this thread. */ + ++result->attached_threads; detach_arena (replaced_arena); } @@ -851,6 +851,8 @@ reused_arena (mstate avoid_arena) if (next_to_use == NULL) next_to_use = &main_arena; + /* Iterate over all arenas (including those linked from + free_list). */ result = next_to_use; do { @@ -885,6 +887,8 @@ reused_arena (mstate avoid_arena) (void) mutex_lock (&result->mutex); out: + /* Attach the arena to the current thread. Note that we may have + selected an arena which was on free_list. */ { mstate replaced_arena; arena_lookup (replaced_arena); Index: glibc-2.22/malloc/tst-malloc-thread-exit.c =================================================================== --- /dev/null +++ glibc-2.22/malloc/tst-malloc-thread-exit.c @@ -0,0 +1,217 @@ +/* Test malloc with concurrent thread termination. + Copyright (C) 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/>. */ + +/* This thread spawns a number of outer threads, equal to the arena + limit. The outer threads run a loop which start and join two + different kinds of threads: the first kind allocates (attaching an + arena to the thread; malloc_first_thread) and waits, the second + kind waits and allocates (wait_first_threads). Both kinds of + threads exit immediately after waiting. The hope is that this will + exhibit races in thread termination and arena management, + particularly related to the arena free list. */ + +#include <errno.h> +#include <pthread.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> + +#define TIMEOUT 7 + +static bool termination_requested; +static int inner_thread_count = 4; +static size_t malloc_size = 32; + +static void +__attribute__ ((noinline, noclone)) +unoptimized_free (void *ptr) +{ + free (ptr); +} + +static void * +malloc_first_thread (void * closure) +{ + pthread_barrier_t *barrier = closure; + void *ptr = malloc (malloc_size); + if (ptr == NULL) + { + printf ("error: malloc: %m\n"); + abort (); + } + int ret = pthread_barrier_wait (barrier); + if (ret != 0 && ret != PTHREAD_BARRIER_SERIAL_THREAD) + { + errno = ret; + printf ("error: pthread_barrier_wait: %m\n"); + abort (); + } + unoptimized_free (ptr); + return NULL; +} + +static void * +wait_first_thread (void * closure) +{ + pthread_barrier_t *barrier = closure; + int ret = pthread_barrier_wait (barrier); + if (ret != 0 && ret != PTHREAD_BARRIER_SERIAL_THREAD) + { + errno = ret; + printf ("error: pthread_barrier_wait: %m\n"); + abort (); + } + void *ptr = malloc (malloc_size); + if (ptr == NULL) + { + printf ("error: malloc: %m\n"); + abort (); + } + unoptimized_free (ptr); + return NULL; +} + +static void * +outer_thread (void *closure) +{ + pthread_t *threads = calloc (sizeof (*threads), inner_thread_count); + if (threads == NULL) + { + printf ("error: calloc: %m\n"); + abort (); + } + + while (!__atomic_load_n (&termination_requested, __ATOMIC_RELAXED)) + { + pthread_barrier_t barrier; + int ret = pthread_barrier_init (&barrier, NULL, inner_thread_count + 1); + if (ret != 0) + { + errno = ret; + printf ("pthread_barrier_init: %m\n"); + abort (); + } + for (int i = 0; i < inner_thread_count; ++i) + { + void *(*func) (void *); + if ((i % 2) == 0) + func = malloc_first_thread; + else + func = wait_first_thread; + ret = pthread_create (threads + i, NULL, func, &barrier); + if (ret != 0) + { + errno = ret; + printf ("error: pthread_create: %m\n"); + abort (); + } + } + ret = pthread_barrier_wait (&barrier); + if (ret != 0 && ret != PTHREAD_BARRIER_SERIAL_THREAD) + { + errno = ret; + printf ("pthread_wait: %m\n"); + abort (); + } + for (int i = 0; i < inner_thread_count; ++i) + { + ret = pthread_join (threads[i], NULL); + if (ret != 0) + { + ret = errno; + printf ("error: pthread_join: %m\n"); + abort (); + } + } + ret = pthread_barrier_destroy (&barrier); + if (ret != 0) + { + ret = errno; + printf ("pthread_barrier_destroy: %m\n"); + abort (); + } + } + + free (threads); + + return NULL; +} + +static int +do_test (void) +{ + /* The number of top-level threads should be equal to the number of + arenas. See arena_get2. */ + long outer_thread_count = sysconf (_SC_NPROCESSORS_ONLN); + if (outer_thread_count >= 1) + { + /* See NARENAS_FROM_NCORES in malloc.c. */ + if (sizeof (long) == 4) + outer_thread_count *= 2; + else + outer_thread_count *= 8; + } + + /* Leave some room for shutting down all threads gracefully. */ + int timeout = TIMEOUT - 2; + + pthread_t *threads = calloc (sizeof (*threads), outer_thread_count); + if (threads == NULL) + { + printf ("error: calloc: %m\n"); + abort (); + } + + for (long i = 0; i < outer_thread_count; ++i) + { + int ret = pthread_create (threads + i, NULL, outer_thread, NULL); + if (ret != 0) + { + errno = ret; + printf ("error: pthread_create: %m\n"); + abort (); + } + } + + struct timespec ts = {timeout, 0}; + if (nanosleep (&ts, NULL)) + { + printf ("error: error: nanosleep: %m\n"); + abort (); + } + + __atomic_store_n (&termination_requested, true, __ATOMIC_RELAXED); + + for (long i = 0; i < outer_thread_count; ++i) + { + int ret = pthread_join (threads[i], NULL); + if (ret != 0) + { + errno = ret; + printf ("error: pthread_join: %m\n"); + abort (); + } + } + free (threads); + + return 0; +} + +#define TEST_FUNCTION do_test () +#include "../test-skeleton.c"
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