Add a stripped build and checkpatch to CI

.github/scripts/checkpatch.sh

@@ -0,0 +1,96 @@
+#!/bin/bash
+
+# SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0+
+
+# Usage: .github/scripts/checkpatch.sh <base> <linux> [stripped]
+#
+# Run checkpatch on the change from commit <base> to the working tree, in the
+# same way as the netdev patch checks (NIPA). <linux> is a Linux source tree;
+# its scripts/checkpatch.pl is used. Run this from the top of the repository.
+#
+# Without "stripped", check the module sources as they are (CHECK_SRCS in the
+# Makefile, as "make checkpatch"). With "stripped", check the files that go
+# upstream, after util/strip.py (as "make checkpatch-net-next"). util/ and
+# test/ are not checked. The main branch has checkpatch findings of its own,
+# so only the change is checked.
+#
+# The exit status is 1 if checkpatch reports an error, and 0 otherwise:
+# warnings and checks do not fail, as in NIPA.
+
+set -e
+
+if [ $# -lt 2 ] || [ $# -gt 3 ] || [ "${3:-stripped}" != stripped ]; then
+	echo "Usage: $0 <base> <linux> [stripped]" >&2
+	exit 2
+fi
+base=$1
+linux=$2
+stripped=$3
+work=$(mktemp -d)
+trap 'rm -rf $work' EXIT
+
+# Put into directory $2 the code of tree $1 that checkpatch must see.
+prepare_tree() {
+	local tree=$1 out=$2 srcs
+
+	if [ -n "$stripped" ]; then
+		# "make net-next" writes the stripped files into a Linux source
+		# tree: the module into net/homa and homa.h into
+		# include/uapi/linux.
+		mkdir -p $out/net $out/include/uapi/linux
+		make -s -C $tree net-next LINUX_SRC_DIR=$out HOMA_TARGET=$out/net/homa
+	else
+		# "make print-CHECK_SRCS" prints "CHECK_SRCS = <files>".
+		srcs=$(make -s -C $tree print-CHECK_SRCS | sed 's/^CHECK_SRCS = //')
+		mkdir -p $out
+		(cd $tree && cp $srcs $out/)
+	fi
+}
+
+# Check the diff in file $1 with the options of NIPA
+# (tests/patch/checkpatch/checkpatch.sh). The diff is not in a Linux tree and
+# has no commit message: hence --no-tree, --no-signoff and COMMIT_MESSAGE, and
+# NIPA's ignored types for commit messages are left out.
+run_checkpatch() {
+	local diff=$1 result=$work/checkpatch.out
+
+	# checkpatch exits with 1 for warnings and checks too, so its exit
+	# status is not used; the result is read below.
+	$linux/scripts/checkpatch.pl --strict --codespell --max-line-length=80 \
+		--no-tree --no-signoff --color=never \
+		--ignore=COMMIT_MESSAGE,MACRO_ARG_REUSE,ALLOC_SIZEOF_STRUCT,CAMELCASE,FILE_PATH_CHANGES \
+		$diff > $result || true
+
+	# In GitHub Actions, a line that starts with "::warning::" shows as an
+	# annotation, so add it to warnings and checks there.
+	if [ -n "$GITHUB_ACTIONS" ]; then
+		sed -E 's/^(WARNING|CHECK):/::warning::&/' $result
+	else
+		cat $result
+	fi
+
+	if grep -q '^ERROR:' $result; then
+		echo "checkpatch found errors."
+		return 1
+	fi
+}
+
+# Prepare this tree first, so that a util/strip.py failure always shows.
+prepare_tree . $work/head
+
+if ! git cat-file -e "$base^{commit}" 2>/dev/null; then
+	echo "Base commit '$base' is not in this repository: checkpatch skipped."
+	exit 0
+fi
+mkdir $work/base-src
+git archive $base | tar -x -C $work/base-src
+prepare_tree $work/base-src $work/base
+
+cd $work
+# diff exits with 1 when the trees differ, which is the normal case.
+diff -ruN base head > change.diff || true
+if [ ! -s change.diff ]; then
+	echo "The change does not touch checked code: checkpatch skipped."
+	exit 0
+fi
+run_checkpatch change.diff

.github/workflows/ci.yml

@@ -8,11 +8,15 @@ jobs:
     runs-on: ubuntu-24.04
     env:
       LINUX_VERSION: 6.17.8
+      # The base for checkpatch: a pull request's base, or the branch tip before a push.
+      BASE_SHA: ${{ github.event.pull_request.base.sha || github.event.before }}
     steps:
       - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0  # the strip check needs a pull request's base
 
       - name: Install kernel build dependencies
-        run: sudo apt-get update && sudo apt-get install -y flex bison bc libelf-dev libssl-dev
+        run: sudo apt-get update && sudo apt-get install -y flex bison bc libelf-dev libssl-dev codespell
 
       # The unit tests compile against kernel headers, which need a
       # configured tree; modules_prepare is enough, no vmlinux.
@@ -42,3 +46,27 @@ jobs:
       - name: Unit tests (IPv4)
         if: ${{ !cancelled() }}
         run: cd test && ./unit --ipv4
+
+      # The stripped version (__STRIP__=1), with the same kernel.
+      - name: Build homa.ko (stripped)
+        if: ${{ !cancelled() }}
+        run: make KBUILD_MODPOST_WARN=1 __STRIP__=1
+
+      # Clean first: both versions of the unit tests use the same object files.
+      - name: Unit tests, stripped (IPv6)
+        if: ${{ !cancelled() }}
+        run: make -C test clean && make -C test -j$(nproc) __STRIP__=1 unit && cd test && ./unit
+
+      - name: Unit tests, stripped (IPv4)
+        if: ${{ !cancelled() }}
+        run: cd test && ./unit --ipv4
+
+      # checkpatch the change of a pull request or push (see the script):
+      # the module sources as they are, then the files that go upstream.
+      - name: checkpatch
+        if: ${{ !cancelled() }}
+        run: .github/scripts/checkpatch.sh "$BASE_SHA" $KDIR
+
+      - name: checkpatch (stripped)
+        if: ${{ !cancelled() }}
+        run: .github/scripts/checkpatch.sh "$BASE_SHA" $KDIR stripped