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From:   Ian Rogers <irogers@google.com>
Date:   Wed, 26 Jul 2023 10:26:48 -0700
Message-ID: <CAP-5=fV5NZTFM_9+KnKhZKWmnqc223koOioE9O6hzAvPMrxy7g@mail.gmail.com>
Subject: Re: [PATCH] tools/mm: fix undefined reference to pthread_once
To:     Xie XiuQi <xiexiuqi@huawei.com>
Cc:     akpm@linux-foundation.org, acme@redhat.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, weiyongjun1@huawei.com
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On Tue, Jul 25, 2023 at 2:24=E2=80=AFAM Xie XiuQi <xiexiuqi@huawei.com> wro=
te:
>
> Commit 97d5f2e9ee12 ("tools api fs: More thread safety for global
> filesystem variables") introduces pthread_once, so the libpthread
> should be added at link time, or we'll meet the following compile
> error when 'make -C tools/mm':
>
>   gcc -Wall -Wextra -I../lib/ -o page-types page-types.c ../lib/api/libap=
i.a
>   ~/linux/tools/lib/api/fs/fs.c:146: undefined reference to `pthread_once=
'
>   ~/linux/tools/lib/api/fs/fs.c:147: undefined reference to `pthread_once=
'
>   ~/linux/tools/lib/api/fs/fs.c:148: undefined reference to `pthread_once=
'
>   ~/linux/tools/lib/api/fs/fs.c:149: undefined reference to `pthread_once=
'
>   ~/linux/tools/lib/api/fs/fs.c:150: undefined reference to `pthread_once=
'
>   /usr/bin/ld: ../lib/api/libapi.a(libapi-in.o):~/linux/tools/lib/api/fs/=
fs.c:151:
>   more undefined references to `pthread_once' follow
>   collect2: error: ld returned 1 exit status
>   make: *** [Makefile:22: page-types] Error 1
>
> Fixes: 97d5f2e9ee12 ("tools api fs: More thread safety for global filesys=
tem variables")
> Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>

Apologies.
Acked-by: Ian Rogers <irogers@google.com>

Alternatively we could #ifdef the behavior, but this way is cleaner imo.

Thanks,
Ian

> ---
>  tools/mm/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/mm/Makefile b/tools/mm/Makefile
> index 6c1da51f4177..9997b2e401ae 100644
> --- a/tools/mm/Makefile
> +++ b/tools/mm/Makefile
> @@ -9,7 +9,7 @@ LIB_DIR =3D ../lib/api
>  LIBS =3D $(LIB_DIR)/libapi.a
>
>  CFLAGS +=3D -Wall -Wextra -I../lib/
> -LDFLAGS +=3D $(LIBS)
> +LDFLAGS +=3D $(LIBS) -lpthread
>
>  all: $(TARGETS)
>
> --
> 2.25.1
>