[OE-core] [PATCH] kernel.bbclass: Fix race condition

[Richard Purdie]

On Mon, 2015-05-04 at 17:11 +0300, Ed Bartosh wrote:
> Race condition between do_compile_kernelmodules and do_shared_workdir
> tasks occurs when do_compilemodules changes files in include/generated/*
> while do_shared_workdir tries to copy them to shared working directory.
> 
> Functionality of do_shared_workdir has been moved to separate function
> mk_shared_workdir and called from do_kernel_compile. do_shared_workdir
> left in the code as it may be used in many recipes.
> 
> [YOCTO #7321]
> 
> Signed-off-by: Ed Bartosh <ed.bartosh at linux.intel.com>
> Signed-off-by: Bruce Ashfield <bruce.ashfield at windriver.com>
> ---
>  meta/classes/kernel.bbclass | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/meta/classes/kernel.bbclass b/meta/classes/kernel.bbclass
> index 125ed88..13c0180 100644
> --- a/meta/classes/kernel.bbclass
> +++ b/meta/classes/kernel.bbclass
> @@ -192,6 +192,8 @@ kernel_do_compile() {
>  	if test "${KERNEL_IMAGETYPE_FOR_MAKE}.gz" = "${KERNEL_IMAGETYPE}"; then
>  		gzip -9c < "${KERNEL_IMAGETYPE_FOR_MAKE}" > "${KERNEL_OUTPUT}"
>  	fi
> +
> +	mk_shared_workdir
>  }
>  
>  do_compile_kernelmodules() {
> @@ -245,7 +247,7 @@ emit_depmod_pkgdata() {
>  
>  PACKAGEFUNCS += "emit_depmod_pkgdata"
>  
> -do_shared_workdir () {
> +mk_shared_workdir () {
>  	cd ${B}
>  
>  	kerneldir=${STAGING_KERNEL_BUILDDIR}
> @@ -289,6 +291,14 @@ do_shared_workdir () {
>  	fi
>  }
>  
> +# NOTE!!! Functionality of do_shared_workdir has been moved to mk_shared_workdir
> +# and called from kernel_do_compile.
> +# It caused race condition with do_compile_kernelmodules when it runs
> +# in parallel with do_compile_kernelmodules
> +do_shared_workdir () {
> +	:
> +}
> +
>  # We don't need to stage anything, not the modules/firmware since those would clash with linux-firmware
>  sysroot_stage_all () {
>  	:

This fails on the autobuilder with a missing kernel-None package.
Building lttng-modules, then looking at the package dependencies 100%
reproduces. The problem is this line:

echo "${KERNEL_VERSION}" > $kerneldir/kernel-abiversion

since KERNEL_VERSION is obtained from ${B} via:

KERNEL_VERSION = "${@get_kernelversion_headers('${B}')}"

and ${B} isn't populated when the do_compile shell script is generated
resulting in the file containing "None".

Cheers,

Richard