Re: [PATCH 3/3] fix race-cond between default and custom initrd

[Jan Kiszka <jan.kiszka@siemens.com>]

On 17.02.23 11:01, Felix Moessbauer wrote:
> This patch fixes a data race happening when building a custom initrd.
> Previously, both custom and default initrds were deployed to the image
> deploy dir. The race is fixed by conditionally deploying either the
> custom or the default one. For that, we introduce a new variable
> INITRD_DEPLOY_FILE which provides the name of the initrd in the deploy
> directory. The existing INITRD_IMAGE variable is defaulted to the empty
> string and used to control if a custom initrd is requrested. Only if
> this variable is empty, the default one is deployed.
> 

So, if I understand this correctly, the whole change comes effectively
without a change visible at recipe level IF users already overwrote
INITRD_IMAGE (like isar-cip-core did). Still, this nicely enhanced or
clarified semantic of INITRD_IMAGE should be documented as recipe-api
change.

And then we are lacking an in-tree test case for such a scenario. Some
WIC image that consumes a custom initramfs. We only have
mc:qemuamd64-bullseye:isar-initramfs in the test cases. Not a must-have
to move forward with this improvements, but likely an important
follow-up topic.

Jan

> Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> ---
>  meta/classes/image.bbclass | 24 ++++++++++++++----------
>  scripts/start_vm           |  4 ++--
>  testsuite/start_vm.py      |  2 +-
>  3 files changed, 17 insertions(+), 13 deletions(-)
> 
> diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
> index e799d1d4..0d5a521e 100644
> --- a/meta/classes/image.bbclass
> +++ b/meta/classes/image.bbclass
> @@ -3,7 +3,7 @@
>  
>  # Make workdir and stamps machine-specific without changing common PN target
>  WORKDIR = "${TMPDIR}/work/${DISTRO}-${DISTRO_ARCH}/${PN}-${MACHINE}/${PV}-${PR}"
> -DEPLOYDIR = "${WORKDIR}/deploy-${PN}"
> +DEPLOYDIR = "${WORKDIR}/deploy"
>  STAMP = "${STAMPS_DIR}/${DISTRO}-${DISTRO_ARCH}/${PN}-${MACHINE}/${PV}-${PR}"
>  STAMPCLEAN = "${STAMPS_DIR}/${DISTRO}-${DISTRO_ARCH}/${PN}-${MACHINE}/*-*"
>  
> @@ -22,8 +22,9 @@ IMAGE_INSTALL += "${KERNEL_IMAGE_PKG}"
>  IMAGE_FULLNAME = "${PN}-${DISTRO}-${MACHINE}"
>  
>  # These variables are used by wic and start_vm
> -KERNEL_IMAGE ?= "${IMAGE_FULLNAME}-${KERNEL_FILE}"
> -INITRD_IMAGE ?= "${IMAGE_FULLNAME}-initrd.img"
> +KERNEL_IMAGE = "${IMAGE_FULLNAME}-${KERNEL_FILE}"
> +INITRD_IMAGE ?= ""
> +INITRD_DEPLOY_FILE = "${@d.getVar('INITRD_IMAGE') or '${IMAGE_FULLNAME}-initrd.img')"
>  
>  # This defines the deployed dtbs for reuse by imagers
>  DTB_FILES ?= ""
> @@ -353,7 +354,7 @@ EOF
>  
>  # Default kernel, initrd and dtb image deploy paths (inside imager)
>  KERNEL_IMG = "${PP_DEPLOY}/${KERNEL_IMAGE}"
> -INITRD_IMG = "${PP_DEPLOY}/${INITRD_IMAGE}"
> +INITRD_IMG = "${PP_DEPLOY}/${INITRD_DEPLOY_FILE}"
>  # only one dtb file supported, pick the first
>  DTB_IMG = "${PP_DEPLOY}/${@(d.getVar('DTB_FILES').split() or [''])[0]}"
>  
> @@ -370,12 +371,15 @@ do_copy_boot_files() {
>          sudo cat "$kernel" > "${DEPLOYDIR}/${KERNEL_IMAGE}"
>      fi
>  
> -    initrd="$(realpath -q '${IMAGE_ROOTFS}/initrd.img')"
> -    if [ ! -f "$initrd" ]; then
> -        initrd="$(realpath -q '${IMAGE_ROOTFS}/boot/initrd.img')"
> -    fi
> -    if [ -f "$initrd" ]; then
> -        cp -f "$initrd" '${DEPLOYDIR}/${INITRD_IMAGE}'
> +    # deploy default initrd if no custom one is build
> +    if [ -e "${INITRD_IMAGE}" ]; then
> +        initrd="$(realpath -q '${IMAGE_ROOTFS}/initrd.img')"
> +        if [ ! -f "$initrd" ]; then
> +            initrd="$(realpath -q '${IMAGE_ROOTFS}/boot/initrd.img')"
> +        fi
> +        if [ -f "$initrd" ]; then
> +            cp -f "$initrd" '${DEPLOYDIR}/${INITRD_DEPLOY_FILE}'
> +        fi
>      fi
>  
>      for file in ${DTB_FILES}; do
> diff --git a/scripts/start_vm b/scripts/start_vm
> index 17091d72..8c696a4a 100755
> --- a/scripts/start_vm
> +++ b/scripts/start_vm
> @@ -125,10 +125,10 @@ case "$IMAGE_FSTYPES" in
>      readonly ROOTFS_IMAGE=$IMAGE_FULLNAME.ext4
>  
>      eval $(bitbake -e mc:qemu$ARCH-$DISTRO:isar-image-base | grep "^KERNEL_IMAGE=")
> -    eval $(bitbake -e mc:qemu$ARCH-$DISTRO:isar-image-base | grep "^INITRD_IMAGE=")
> +    eval $(bitbake -e mc:qemu$ARCH-$DISTRO:isar-image-base | grep "^INITRD_DEPLOY_FILE=")
>      QKERNEL=$IMAGE_DIR/${KERNEL_IMAGE}
>      QINITRD=/dev/null
> -    [ -n "$INITRD_IMAGE" ] && QINITRD=$IMAGE_DIR/${INITRD_IMAGE}
> +    [ -n "$INITRD_DEPLOY_FILE" ] && QINITRD=$IMAGE_DIR/${INITRD_DEPLOY_FILE}
>      if [ "$ARCH" = "riscv64" ]; then
>          EXTRA_ARGS="$EXTRA_ARGS -device loader,file=$QKERNEL,addr=0x80200000"
>          QKERNEL="/usr/lib/riscv64-linux-gnu/opensbi/qemu/virt/fw_jump.elf"
> diff --git a/testsuite/start_vm.py b/testsuite/start_vm.py
> index 82ecc17d..ba1ba127 100755
> --- a/testsuite/start_vm.py
> +++ b/testsuite/start_vm.py
> @@ -35,7 +35,7 @@ def format_qemu_cmdline(arch, build, distro, out, pid, enforce_pcbios=False):
>      if image_type == 'ext4':
>          rootfs_image = 'isar-image-base-' + base + '-' + distro + '-qemu' + arch + '.ext4'
>          kernel_image = deploy_dir_image + '/' + get_bitbake_var(bb_output, 'KERNEL_IMAGE')
> -        initrd_image = get_bitbake_var(bb_output, 'INITRD_IMAGE')
> +        initrd_image = get_bitbake_var(bb_output, 'INITRD_DEPLOY_FILE')
>  
>          if not initrd_image:
>              initrd_image = '/dev/null'

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