Re: [PATCH] stdlib: Undo post review change to 16adc58e73f3 [BZ #27749]

[Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>]

On 18/02/23 17:53, Vitaly Buka wrote:
> Post review removal of "goto restart" from
> https://sourceware.org/pipermail/libc-alpha/2021-April/125470.html
> introduced a bug when some atexit handers skipped.
> 
> Signed-off-by: Vitaly Buka <vitalybuka@google.com>

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  stdlib/Makefile                |  1 +
>  stdlib/exit.c                  |  7 +++-
>  stdlib/test-atexit-recursive.c | 75 ++++++++++++++++++++++++++++++++++
>  3 files changed, 81 insertions(+), 2 deletions(-)
>  create mode 100644 stdlib/test-atexit-recursive.c
> 
> diff --git a/stdlib/Makefile b/stdlib/Makefile
> index ff5096ad1b..cd32f53b56 100644
> --- a/stdlib/Makefile
> +++ b/stdlib/Makefile
> @@ -171,6 +171,7 @@ tests := \
>    test-a64l \
>    test-at_quick_exit-race \
>    test-atexit-race \
> +  test-atexit-recursive \
>    test-bz22786 \
>    test-canon \
>    test-canon2 \
> diff --git a/stdlib/exit.c b/stdlib/exit.c
> index 6b1eed6445..1cd0bdfe94 100644
> --- a/stdlib/exit.c
> +++ b/stdlib/exit.c
> @@ -51,7 +51,10 @@ __run_exit_handlers (int status, struct exit_function_list **listp,
>       exit (). */
>    while (true)
>      {
> -      struct exit_function_list *cur = *listp;
> +      struct exit_function_list *cur;
> +
> +    restart:
> +      cur = *listp;
>  
>        if (cur == NULL)
>  	{
> @@ -113,7 +116,7 @@ __run_exit_handlers (int status, struct exit_function_list **listp,
>  	  if (__glibc_unlikely (new_exitfn_called != __new_exitfn_called))
>  	    /* The last exit function, or another thread, has registered
>  	       more exit functions.  Start the loop over.  */
> -            continue;
> +	    goto restart;
>  	}
>  
>        *listp = cur->next;
> diff --git a/stdlib/test-atexit-recursive.c b/stdlib/test-atexit-recursive.c
> new file mode 100644
> index 0000000000..0596b9763b
> --- /dev/null
> +++ b/stdlib/test-atexit-recursive.c
> @@ -0,0 +1,75 @@
> +/* Support file for atexit/exit, etc. race tests (BZ #27749).
> +   Copyright (C) 2023 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/>.  */
> +
> +/* Check that atexit handler registed from another handler still called. */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +#include <support/xunistd.h>
> +#include <sys/wait.h>
> +#include <unistd.h>
> +
> +static void
> +atexit_cb (void)
> +{
> +}
> +
> +static void
> +atexit_last (void)
> +{
> +  _exit (1);
> +}
> +
> +static void
> +atexit_recursive (void)
> +{
> +  atexit (&atexit_cb);
> +  atexit (&atexit_last);
> +}
> +
> +_Noreturn static void
> +test_and_exit (int count)
> +{
> +  for (int i = 0; i < count; ++i)
> +    atexit (&atexit_cb);
> +  atexit (&atexit_recursive);
> +  exit (0);
> +}
> +
> +static int
> +do_test (void)
> +{
> +  for (int i = 0; i < 100; ++i)
> +    if (xfork () == 0)
> +      test_and_exit (i);
> +
> +  for (int i = 0; i < 100; ++i)
> +    {
> +      int status;
> +      xwaitpid (0, &status, 0);
> +      if (!WIFEXITED (status))
> +	FAIL_EXIT1 ("Failed iterations %d", i);
> +      TEST_COMPARE (WEXITSTATUS (status), 1);
> +    }
> +
> +  return 0;
> +}
> +
> +#define TEST_FUNCTION do_test
> +#include <support/test-driver.c>