docs: Makefile: Use CONFIG_SHELL not SHELL

Fix think-o about which variable to find the Kbuild-configured shell.
This has accidentally worked due to most shells setting $SHELL by
default.

Fixes: 51e46c7a4007 ("docs, parallelism: Rearrange how jobserver reservations are made")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210617225808.3907377-1-keescook@chromium.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 9c42dde..c3feb65 100644 (file)
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -76,7 +76,7 @@ quiet_cmd_sphinx = SPHINX  $@ --> file://$(abspath $(BUILDDIR)/$3/$4)
        PYTHONDONTWRITEBYTECODE=1 \
        BUILDDIR=$(abspath $(BUILDDIR)) SPHINX_CONF=$(abspath $(srctree)/$(src)/$5/$(SPHINX_CONF)) \
        $(PYTHON3) $(srctree)/scripts/jobserver-exec \
-       $(SHELL) $(srctree)/Documentation/sphinx/parallel-wrapper.sh \
+       $(CONFIG_SHELL) $(srctree)/Documentation/sphinx/parallel-wrapper.sh \
        $(SPHINXBUILD) \
        -b $2 \
        -c $(abspath $(srctree)/$(src)) \