From 61419aae264069ed1f8bce34ad3a5cf7d26fcbae Mon Sep 17 00:00:00 2001
From: Andrii Nakryiko <andriin@fb.com>
Date: Thu, 18 Apr 2019 15:24:21 -0700
Subject: [PATCH] sync-kernel.sh: detect synced commits, interactively resolve
 conflicts

1. There is one commit ("libbpf: fix btf_dedup equivalence check
   handling of different kinds"), which was originally committed into bpf
   tree and manually synced into libbpf (it was a critical bug fix). Now
   that bpf and bpf-next trees were merged, this causes duplicate commits in
   libbpf. To address this, check is added to see if libbpf repo already has
   a commit with the same subject and allow to skip it.
2. Just checking by subject is not good enough, as we currently have few
   different commits with the same subject "bpf: Sync bpf.h to tools/".
   To address this, script now will ask user whether to skip or cherry-pick
   commit. This allows for human to double-check the commit and make
   informed devision.
3. There is a commit ('bfb35c27c65f bpf: fix whitespace for ENCAP_L2
   defines in bpf.h'), which modifies both include/uapi/linux/bpf.h and
   tools/include/uapi/linux/bpf.h in the same commit. This break the
   sync script, as it doesn't cherry-pick commits that hasn't modified
   libbpf files. So at the time that commit bfb35c27c65f is applied, linux
   repo is missing some preceding changes to include/uapi/linux/bpf.h. They
   would normally be ignored later during repo filtering, but to do
   cherry-pick they are necessary. It's hard to fix it automatically, so
   script will wait for user to resolve the issue and continue.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
 scripts/sync-kernel.sh | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/scripts/sync-kernel.sh b/scripts/sync-kernel.sh
index 74d3342..68cec4a 100755
--- a/scripts/sync-kernel.sh
+++ b/scripts/sync-kernel.sh
@@ -77,9 +77,31 @@ for LIBBPF_NEW_MERGE in ${LIBBPF_NEW_MERGES}; do
 	fi
 done
 
+cd ${WORKDIR} && cd ${LIBBPF_REPO}
+git log --oneline -n500 > ${TMP_DIR}/libbpf_commits.txt
+cd ${WORKDIR} && cd ${LINUX_REPO}
+
 LIBBPF_NEW_COMMITS=$(git rev-list --no-merges --topo-order --reverse ${BASELINE_TAG}..${TIP_TAG} ${LIBBPF_PATHS[@]})
 for LIBBPF_NEW_COMMIT in ${LIBBPF_NEW_COMMITS}; do
-	git cherry-pick ${LIBBPF_NEW_COMMIT}
+	echo "Checking commit '${LIBBPF_NEW_COMMIT}'"
+	SYNCED_COMMITS=$(grep -F "$(git log -n1 --pretty=format:%s ${LIBBPF_NEW_COMMIT})" ${TMP_DIR}/libbpf_commits.txt || echo "")
+	if [ -n "${SYNCED_COMMITS}" ]; then
+		# commit with the same subject is already in libbpf, but it's not 100% the same commit, so check with user
+		echo "Commit '$(git log -n1 --oneline ${LIBBPF_NEW_COMMIT})' appears to be already synced into libbpf..."
+		echo "Corresponding libbpf commit(s):"
+		echo "${SYNCED_COMMITS}"
+		read -p "Do you want to skip it? [y/N]: " SHOULD_SKIP
+		case "${SHOULD_SKIP}" in 
+			"y" | "Y")
+				echo "Skipping '$(git log -n1 --oneline ${LIBBPF_NEW_COMMIT})'..."
+				continue
+				;;
+		esac
+	fi
+	# commit hasn't been synced into libbpf yet
+	if ! git cherry-pick ${LIBBPF_NEW_COMMIT}; then 
+		read -p "Cherry-picking '$(git log --oneline -n1 ${LIBBPF_NEW_COMMIT})' failed, please fix manually and press <return> to proceed..."
+	fi
 done
 
 LIBBPF_TREE_FILTER='												\