Fix pining maps after reuse map fd

.travis.yml

@@ -0,0 +1,33 @@
+sudo: required
+language: bash
+dist: bionic
+services:
+    - docker
+
+env:
+    global:
+        - PROJECT_NAME='libbpf'
+        - AUTHOR_EMAIL="$(git log -1 --pretty=\"%aE\")"
+        - REPO_ROOT="$TRAVIS_BUILD_DIR"
+        - CI_ROOT="$REPO_ROOT/travis-ci"
+        - VMTEST_ROOT="$CI_ROOT/vmtest"
+
+addons:
+    apt:
+        packages:
+            - qemu-kvm
+            - zstd
+            - binutils-dev
+            - elfutils
+            - libcap-dev
+            - libelf-dev
+            - libdw-dev
+            - python3-docutils
+
+jobs:
+    include:
+        - stage: Builds & Tests
+          name: Kernel LATEST + selftests
+          language: bash
+          env: KERNEL=LATEST
+          script:  $CI_ROOT/vmtest/run_vmtest.sh || travis_terminate 1

tools/lib/bpf/libbpf.c

@@ -4203,6 +4203,36 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map)
 	return 0;
 }
 
+static int init_map_slots(struct bpf_map *map)
+{
+	const struct bpf_map *targ_map;
+	unsigned int i;
+	int fd, err;
+
+	for (i = 0; i < map->init_slots_sz; i++) {
+		if (!map->init_slots[i])
+			continue;
+
+		targ_map = map->init_slots[i];
+		fd = bpf_map__fd(targ_map);
+		err = bpf_map_update_elem(map->fd, &i, &fd, 0);
+		if (err) {
+			err = -errno;
+			pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",
+				map->name, i, targ_map->name,
+				fd, err);
+			return err;
+		}
+		pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
+			 map->name, i, targ_map->name, fd);
+	}
+
+	zfree(&map->init_slots);
+	map->init_slots_sz = 0;
+
+	return 0;
+}
+
 static int
 bpf_object__create_maps(struct bpf_object *obj)
 {
@@ -4226,47 +4256,29 @@ bpf_object__create_maps(struct bpf_object *obj)
 		if (map->fd >= 0) {
 			pr_debug("map '%s': skipping creation (preset fd=%d)\n",
 				 map->name, map->fd);
-			continue;
-		}
-
-		err = bpf_object__create_map(obj, map);
-		if (err)
-			goto err_out;
-
-		pr_debug("map '%s': created successfully, fd=%d\n", map->name,
-			 map->fd);
-
-		if (bpf_map__is_internal(map)) {
-			err = bpf_object__populate_internal_map(obj, map);
-			if (err < 0) {
-				zclose(map->fd);
+		} else {
+			err = bpf_object__create_map(obj, map);
+			if (err)
 				goto err_out;
-			}
-		}
 
-		if (map->init_slots_sz) {
-			for (j = 0; j < map->init_slots_sz; j++) {
-				const struct bpf_map *targ_map;
-				int fd;
+			pr_debug("map '%s': created successfully, fd=%d\n",
+				 map->name, map->fd);
 
-				if (!map->init_slots[j])
-					continue;
+			if (bpf_map__is_internal(map)) {
+				err = bpf_object__populate_internal_map(obj, map);
+				if (err < 0) {
+					zclose(map->fd);
+					goto err_out;
+				}
+			}
 
-				targ_map = map->init_slots[j];
-				fd = bpf_map__fd(targ_map);
-				err = bpf_map_update_elem(map->fd, &j, &fd, 0);
-				if (err) {
-					err = -errno;
-					pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",
-						map->name, j, targ_map->name,
-						fd, err);
+			if (map->init_slots_sz) {
+				err = init_map_slots(map);
+				if (err < 0) {
+					zclose(map->fd);
 					goto err_out;
 				}
-				pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
-					 map->name, j, targ_map->name, fd);
 			}
-			zfree(&map->init_slots);
-			map->init_slots_sz = 0;
 		}
 
 		if (map->pin_path && !map->pinned) {

tools/testing/selftests/bpf/prog_tests/pinning.c

@@ -37,7 +37,7 @@ void test_pinning(void)
 	struct stat statbuf = {};
 	struct bpf_object *obj;
 	struct bpf_map *map;
-	int err;
+	int err, map_fd;
 	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
 		.pin_root_path = custpath,
 	);
@@ -213,6 +213,53 @@ void test_pinning(void)
 	if (CHECK(err, "stat custpinpath", "err %d errno %d\n", err, errno))
 		goto out;
 
+	/* remove the custom pin path to re-test it with reuse fd below */
+	err = unlink(custpinpath);
+	if (CHECK(err, "unlink custpinpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+	err = rmdir(custpath);
+	if (CHECK(err, "rmdir custpindir", "err %d errno %d\n", err, errno))
+		goto out;
+
+	bpf_object__close(obj);
+
+	/* test pinning at custom path with reuse fd */
+	obj = bpf_object__open_file(file, NULL);
+	err = libbpf_get_error(obj);
+	if (CHECK(err, "default open", "err %d errno %d\n", err, errno)) {
+		obj = NULL;
+		goto out;
+	}
+
+	map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(__u32),
+				sizeof(__u64), 1, 0);
+	if (CHECK(map_fd < 0, "create pinmap manually", "fd %d\n", map_fd))
+		goto out;
+
+	map = bpf_object__find_map_by_name(obj, "pinmap");
+	if (CHECK(!map, "find map", "NULL map"))
+		goto close_map_fd;
+
+	err = bpf_map__reuse_fd(map, map_fd);
+	if (CHECK(err, "reuse pinmap fd", "err %d errno %d\n", err, errno))
+		goto close_map_fd;
+
+	err = bpf_map__set_pin_path(map, custpinpath);
+	if (CHECK(err, "set pin path", "err %d errno %d\n", err, errno))
+		goto close_map_fd;
+
+	err = bpf_object__load(obj);
+	if (CHECK(err, "custom load", "err %d errno %d\n", err, errno))
+		goto close_map_fd;
+
+	/* check that pinmap was pinned at the custom path */
+	err = stat(custpinpath, &statbuf);
+	if (CHECK(err, "stat custpinpath", "err %d errno %d\n", err, errno))
+		goto close_map_fd;
+
+close_map_fd:
+	close(map_fd);
 out:
 	unlink(pinpath);
 	unlink(nopinpath);

travis-ci/managers/debian.sh

@@ -0,0 +1,84 @@
+#!/bin/bash
+
+PHASES=(${@:-SETUP RUN RUN_ASAN CLEANUP})
+DEBIAN_RELEASE="${DEBIAN_RELEASE:-testing}"
+CONT_NAME="${CONT_NAME:-libbpf-debian-$DEBIAN_RELEASE}"
+ENV_VARS="${ENV_VARS:-}"
+DOCKER_RUN="${DOCKER_RUN:-docker run}"
+REPO_ROOT="${REPO_ROOT:-$PWD}"
+ADDITIONAL_DEPS=(clang pkg-config gcc-8)
+CFLAGS="-g -O2 -Werror -Wall"
+
+function info() {
+    echo -e "\033[33;1m$1\033[0m"
+}
+
+function error() {
+    echo -e "\033[31;1m$1\033[0m"
+}
+
+function docker_exec() {
+    docker exec $ENV_VARS -it $CONT_NAME "$@"
+}
+
+set -e
+
+source "$(dirname $0)/travis_wait.bash"
+
+for phase in "${PHASES[@]}"; do
+    case $phase in
+        SETUP)
+            info "Setup phase"
+            info "Using Debian $DEBIAN_RELEASE"
+
+            sudo apt-get -y -o Dpkg::Options::="--force-confnew" install docker-ce
+            docker --version
+
+            docker pull debian:$DEBIAN_RELEASE
+            info "Starting container $CONT_NAME"
+            $DOCKER_RUN -v $REPO_ROOT:/build:rw \
+                        -w /build --privileged=true --name $CONT_NAME \
+                        -dit --net=host debian:$DEBIAN_RELEASE /bin/bash
+            docker_exec bash -c "echo deb-src http://deb.debian.org/debian $DEBIAN_RELEASE main >>/etc/apt/sources.list"
+            docker_exec apt-get -y update
+            docker_exec apt-get -y build-dep libelf-dev
+            docker_exec apt-get -y install libelf-dev
+            docker_exec apt-get -y install "${ADDITIONAL_DEPS[@]}"
+            ;;
+        RUN|RUN_CLANG|RUN_GCC8|RUN_ASAN|RUN_CLANG_ASAN|RUN_GCC8_ASAN)
+            if [[ "$phase" = *"CLANG"* ]]; then
+                ENV_VARS="-e CC=clang -e CXX=clang++"
+                CC="clang"
+            elif [[ "$phase" = *"GCC8"* ]]; then
+                ENV_VARS="-e CC=gcc-8 -e CXX=g++-8"
+                CC="gcc-8"
+            else
+                CFLAGS="${CFLAGS} -Wno-stringop-truncation"
+            fi
+            if [[ "$phase" = *"ASAN"* ]]; then
+                CFLAGS="${CFLAGS} -fsanitize=address,undefined"
+            fi
+            docker_exec mkdir build install
+            docker_exec ${CC:-cc} --version
+            info "build"
+	    docker_exec make -j$((4*$(nproc))) CFLAGS="${CFLAGS}" -C ./src -B OBJDIR=../build
+            info "ldd build/libbpf.so:"
+            docker_exec ldd build/libbpf.so
+            if ! docker_exec ldd build/libbpf.so | grep -q libelf; then
+                error "No reference to libelf.so in libbpf.so!"
+                exit 1
+            fi
+            info "install"
+            docker_exec make -j$((4*$(nproc))) -C src OBJDIR=../build DESTDIR=../install install
+            docker_exec rm -rf build install
+            ;;
+        CLEANUP)
+            info "Cleanup phase"
+            docker stop $CONT_NAME
+            docker rm -f $CONT_NAME
+            ;;
+        *)
+            echo >&2 "Unknown phase '$phase'"
+            exit 1
+    esac
+done

travis-ci/managers/travis_wait.bash

@@ -0,0 +1,61 @@
+# This was borrowed from https://github.com/travis-ci/travis-build/tree/master/lib/travis/build/bash
+# to get around https://github.com/travis-ci/travis-ci/issues/9979. It should probably be removed
+# as soon as Travis CI has started to provide an easy way to export the functions to bash scripts.
+
+travis_jigger() {
+  local cmd_pid="${1}"
+  shift
+  local timeout="${1}"
+  shift
+  local count=0
+
+  echo -e "\\n"
+
+  while [[ "${count}" -lt "${timeout}" ]]; do
+    count="$((count + 1))"
+    echo -ne "Still running (${count} of ${timeout}): ${*}\\r"
+    sleep 60
+  done
+
+  echo -e "\\n${ANSI_RED}Timeout (${timeout} minutes) reached. Terminating \"${*}\"${ANSI_RESET}\\n"
+  kill -9 "${cmd_pid}"
+}
+
+travis_wait() {
+  local timeout="${1}"
+
+  if [[ "${timeout}" =~ ^[0-9]+$ ]]; then
+    shift
+  else
+    timeout=20
+  fi
+
+  local cmd=("${@}")
+  local log_file="travis_wait_${$}.log"
+
+  "${cmd[@]}" &>"${log_file}" &
+  local cmd_pid="${!}"
+
+  travis_jigger "${!}" "${timeout}" "${cmd[@]}" &
+  local jigger_pid="${!}"
+  local result
+
+  {
+    set +e
+    wait "${cmd_pid}" 2>/dev/null
+    result="${?}"
+    ps -p"${jigger_pid}" &>/dev/null && kill "${jigger_pid}"
+    set -e
+  }
+
+  if [[ "${result}" -eq 0 ]]; then
+    echo -e "\\n${ANSI_GREEN}The command ${cmd[*]} exited with ${result}.${ANSI_RESET}"
+  else
+    echo -e "\\n${ANSI_RED}The command ${cmd[*]} exited with ${result}.${ANSI_RESET}"
+  fi
+
+  echo -e "\\n${ANSI_GREEN}Log:${ANSI_RESET}\\n"
+  cat "${log_file}"
+
+  return "${result}"
+}

travis-ci/managers/ubuntu.sh

@@ -0,0 +1,27 @@
+#!/bin/bash
+set -e
+set -x
+
+RELEASE="bionic"
+
+echo "deb-src http://archive.ubuntu.com/ubuntu/ $RELEASE main restricted universe multiverse" >>/etc/apt/sources.list
+
+apt-get update
+apt-get -y build-dep libelf-dev
+apt-get install -y libelf-dev pkg-config
+
+source "$(dirname $0)/travis_wait.bash"
+
+cd $REPO_ROOT
+
+CFLAGS="-g -O2 -Werror -Wall -fsanitize=address,undefined"
+mkdir build install
+cc --version
+make -j$((4*$(nproc))) CFLAGS="${CFLAGS}" -C ./src -B OBJDIR=../build
+ldd build/libbpf.so
+if ! ldd build/libbpf.so | grep -q libelf; then
+    echo "FAIL: No reference to libelf.so in libbpf.so!"
+    exit 1
+fi
+make -j$((4*$(nproc))) -C src OBJDIR=../build DESTDIR=../install install
+rm -rf build install