setlocalversion: use only the correct release tag for git-describe

Currently, setlocalversion uses any annotated tag for git-describe.
If we are at a tagged commit, it will not append the commit hash.

  $ git checkout v6.2-rc1^
  $ make -s defconfig kernelrelease
  6.1.0-14595-g292a089d
  $ git tag -a foo -m foo
  $ make -s kernelrelease
  6.1.0

If a local tag 'foo' exists, it pretends to be a released version
'6.1.0', while there are many commits on top of it.

The output should be consistent irrespective of such a local tag.
Pass the correct release tag to --match option of git-describe.

In the mainline kernel, the SUBLEVEL is always '0', which is omitted
from the tag.

  KERNELVERSION      annotated tag
  6.1.0          ->  v6.1            (mainline)
  6.2.0-rc5      ->  v6.2-rc5        (mainline, release candidate)
  6.1.7          ->  v6.1.7          (stable)

To preserve the behavior in linux-next, use the tag derived from
localversion* files if exists. In linux-next, the local version is
specified by the localversion-next file.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/setlocalversion

@@ -27,6 +27,7 @@ fi
 scm_version()
 {
 	local short
+	local tag
 	short=false
 
 	cd "$srctree"
@@ -42,9 +43,21 @@ scm_version()
 		return
 	fi
 
-	# If we are at a tagged commit (like "v2.6.30-rc6"), we ignore it
-	# because this version is defined in the top level Makefile.
-	if [ -z "$(git describe --exact-match 2>/dev/null)" ]; then
+	# If a localversion*' file and the corresponding annotated tag exist,
+	# use it. This is the case in linux-next.
+	tag=${file_localversion#-}
+	tag=$(git describe --exact-match --match=$tag $tag 2>/dev/null)
+
+	# Otherwise, default to the annotated tag derived from KERNELVERSION.
+	#   mainline kernel:  6.2.0-rc5  ->  v6.2-rc5
+	#   stable kernel:    6.1.7      ->  v6.1.7
+	if [ -z "${tag}" ]; then
+		tag=v$(echo "${KERNELVERSION}" | sed -E 's/^([0-9]+\.[0-9]+)\.0(.*)$/\1\2/')
+	fi
+
+	# If we are at the tagged commit, we ignore it because the version is
+	# well-defined.
+	if [ -z "$(git describe --exact-match --match=$tag 2>/dev/null)" ]; then
 
 		# If only the short version is requested, don't bother
 		# running further git commands
@@ -52,9 +65,9 @@ scm_version()
 			echo "+"
 			return
 		fi
-		# If we are past a tagged commit (like
-		# "v2.6.30-rc5-302-g72357d5"), we pretty print it.
-		if atag="$(git describe 2>/dev/null)"; then
+		# If we are past the tagged commit, we pretty print it.
+		# (like 6.1.0-14595-g292a089d78d3)
+		if atag="$(git describe --match=$tag 2>/dev/null)"; then
 			echo "$atag" | awk -F- '{printf("-%05d", $(NF-1))}'
 		fi
 
@@ -116,7 +129,7 @@ fi
 # version string from CONFIG_LOCALVERSION
 config_localversion=$(sed -n 's/^CONFIG_LOCALVERSION=\(.*\)$/\1/p' include/config/auto.conf)
 
-# scm version string if not at a tagged commit
+# scm version string if not at the kernel version tag or at the file_localversion
 if grep -q "^CONFIG_LOCALVERSION_AUTO=y$" include/config/auto.conf; then
 	# full scm version string
 	scm_version="$(scm_version)"