Re: [dpdk-dev] [PATCH v3] test: remove meson dependency on /proc file

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Apr 10, 2020 at 12:29:50PM +0200, Thomas Monjalon wrote:
> Meson is detecting the path /proc/sys/vm/nr_hugepages in the call to cat
> in app/test/meson.build and then adding it as a build dependency.
> This causes build loop if the timestamp of this file keeps changing.
> 
> It is fixed by hiding hugepage check in a shell script.
> 
> Fixes: 77784ef0fba8 ("test: allow no-huge mode for fast-tests")
> 
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> Tested-by: Lukasz Wojciechowski <l.wojciechow@partner.samsung.com>
> Reviewed-by: Lukasz Wojciechowski <l.wojciechow@partner.samsung.com>
> Acked-by: Aaron Conole <aconole@redhat.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> ---
> 
> v2: use variable as pointed by Lukasz
> v3: avoid TOCTOU issue as suggested by David
> 	I'm afraid it requires to re-confirm every reviews above.
> 
> ---
>  MAINTAINERS              | 1 +
>  app/test/has-hugepage.sh | 9 +++++++++
>  app/test/meson.build     | 8 ++------
>  3 files changed, 12 insertions(+), 6 deletions(-)
>  create mode 100755 app/test/has-hugepage.sh
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 4800f6884a..aa619b6762 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1471,6 +1471,7 @@ F: app/test/Makefile
>  F: app/test/autotest*
>  F: app/test/commands.c
>  F: app/test/get-coremask.sh
> +F: app/test/has-hugepage.sh
>  F: app/test/packet_burst_generator.c
>  F: app/test/packet_burst_generator.h
>  F: app/test/process.h
> diff --git a/app/test/has-hugepage.sh b/app/test/has-hugepage.sh
> new file mode 100755
> index 0000000000..865e66cddd
> --- /dev/null
> +++ b/app/test/has-hugepage.sh
> @@ -0,0 +1,9 @@
> +#! /bin/sh
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright 2020 Mellanox Technologies, Ltd
> +
> +if [ "$(uname)" = "Linux" ] ; then
> +	cat /proc/sys/vm/nr_hugepages || echo 0
> +else
> +	echo 0
> +fi
> diff --git a/app/test/meson.build b/app/test/meson.build
> index 351d29cb65..542408d614 100644
> --- a/app/test/meson.build
> +++ b/app/test/meson.build
> @@ -399,12 +399,8 @@ dpdk_test = executable('dpdk-test',
>  
>  has_hugepage = true
>  if is_linux

Since you check for linux in the script, you can drop these two lines, and
then just replace the whole branch with:

has_hugepages = run_command('has-hugepage.sh').stdout().strip() != '0'

> -	check_hugepage = run_command('cat',
> -				     '/proc/sys/vm/nr_hugepages')
> -	if (check_hugepage.returncode() != 0 or
> -	    check_hugepage.stdout().strip() == '0')
> -		has_hugepage = false
> -	endif
> +	check_hugepage = find_program('has-hugepage.sh')
> +	has_hugepage = run_command(check_hugepage).stdout().strip() != '0'
>  endif
>  message('hugepage availability: @0@'.format(has_hugepage))
>  
> -- 
> 2.26.0
>