Extend the existing bpf_map_lookup_and_delete_elem() functionality to
hashtab maps, in addition to stacks and queues.
Create a new hashtab bpf_map_ops function that does lookup and deletion
of the element under the same bucket lock and add the created map_ops to
bpf.h.
Add the appropriate test cases to 'maps' and 'lru_map' selftests
accompanied with new test_progs.
Cc: Juraj Vijtiuk <juraj.vijtiuk@xxxxxxxxxx>
Cc: Luka Oreskovic <luka.oreskovic@xxxxxxxxxx>
Cc: Luka Perkov <luka.perkov@xxxxxxxxxx>
Signed-off-by: Denis Salopek <denis.salopek@xxxxxxxxxx>
---
v2: Add functionality for LRU/per-CPU, add test_progs tests.
---
include/linux/bpf.h | 2 +
kernel/bpf/hashtab.c | 80 +++++
kernel/bpf/syscall.c | 14 +-
.../bpf/prog_tests/lookup_and_delete.c | 283 ++++++++++++++++++
.../bpf/progs/test_lookup_and_delete.c | 26 ++
tools/testing/selftests/bpf/test_lru_map.c | 8 +
tools/testing/selftests/bpf/test_maps.c | 19 +-
7 files changed, 430 insertions(+), 2 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/lookup_and_delete.c
create mode 100644 tools/testing/selftests/bpf/progs/test_lookup_and_delete.c
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 4c730863fa77..0bcc4f89af40 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -67,6 +67,8 @@ struct bpf_map_ops {
void *(*map_lookup_elem_sys_only)(struct bpf_map *map, void *key);
int (*map_lookup_batch)(struct bpf_map *map, const union bpf_attr *attr,
union bpf_attr __user *uattr);
+ int (*map_lookup_and_delete_elem)(struct bpf_map *map, void *key,
+ void *value);
int (*map_lookup_and_delete_batch)(struct bpf_map *map,
const union bpf_attr *attr,
union bpf_attr __user *uattr);
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 330d721dd2af..8c3334d1b6b3 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -1401,6 +1401,82 @@ static void htab_map_seq_show_elem(struct bpf_map *map, void *key,
rcu_read_unlock();
}
+static int __htab_map_lookup_and_delete_elem(struct bpf_map *map, void *key,
+ void *value, bool is_lru_map,
+ bool is_percpu)
+{
+ struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+ u32 hash, key_size, value_size;
+ struct hlist_nulls_head *head;
+ int cpu, off = 0, ret;
+ struct htab_elem *l;
+ unsigned long flags;
+ void __percpu *pptr;
+ struct bucket *b;
+
+ key_size = map->key_size;
+ value_size = round_up(map->value_size, 8);
+
+ hash = htab_map_hash(key, key_size, htab->hashrnd);
+ b = __select_bucket(htab, hash);
+ head = &b->head;
+
+ ret = htab_lock_bucket(htab, b, hash, &flags);
+ if (ret)
+ return ret;
+
+ l = lookup_elem_raw(head, hash, key, key_size);
+ if (l) {
+ if (is_percpu) {
+ pptr = htab_elem_get_ptr(l, key_size);
+ for_each_possible_cpu(cpu) {
+ bpf_long_memcpy(value + off,
+ per_cpu_ptr(pptr, cpu),
+ value_size);
+ off += value_size;
+ }
+ } else {
+ copy_map_value(map, value, l->key + round_up(key_size, 8));
+ }
+
+ hlist_nulls_del_rcu(&l->hash_node);
+ if (!is_lru_map)
+ free_htab_elem(htab, l);
+ } else
+ ret = -ENOENT;
+
+ htab_unlock_bucket(htab, b, hash, flags);
+
+ if (is_lru_map && l)
+ bpf_lru_push_free(&htab->lru, &l->lru_node);
+
+ return ret;
+}
+
+static int htab_map_lookup_and_delete_elem(struct bpf_map *map,
+ void *key, void *value)
+{
+ return __htab_map_lookup_and_delete_elem(map, key, value, false, false);
+}
+
+static int htab_percpu_map_lookup_and_delete_elem(struct bpf_map *map,
+ void *key, void *value)
+{
+ return __htab_map_lookup_and_delete_elem(map, key, value, false, true);
+}
+
+static int htab_lru_map_lookup_and_delete_elem(struct bpf_map *map, void *key,
+ void *value)
+{
+ return __htab_map_lookup_and_delete_elem(map, key, value, true, false);
+}
+
+static int htab_lru_percpu_map_lookup_and_delete_elem(struct bpf_map *map,
+ void *key, void *value)
+{
+ return __htab_map_lookup_and_delete_elem(map, key, value, true, true);
+}
+
static int
__htab_map_lookup_and_delete_batch(struct bpf_map *map,
const union bpf_attr *attr,
@@ -1934,6 +2010,7 @@ const struct bpf_map_ops htab_map_ops = {
.map_free = htab_map_free,
.map_get_next_key = htab_map_get_next_key,
.map_lookup_elem = htab_map_lookup_elem,
+ .map_lookup_and_delete_elem = htab_map_lookup_and_delete_elem,
.map_update_elem = htab_map_update_elem,
.map_delete_elem = htab_map_delete_elem,
.map_gen_lookup = htab_map_gen_lookup,
@@ -1954,6 +2031,7 @@ const struct bpf_map_ops htab_lru_map_ops = {
.map_free = htab_map_free,
.map_get_next_key = htab_map_get_next_key,
.map_lookup_elem = htab_lru_map_lookup_elem,
+ .map_lookup_and_delete_elem = htab_lru_map_lookup_and_delete_elem,
.map_lookup_elem_sys_only = htab_lru_map_lookup_elem_sys,
.map_update_elem = htab_lru_map_update_elem,
.map_delete_elem = htab_lru_map_delete_elem,
@@ -2077,6 +2155,7 @@ const struct bpf_map_ops htab_percpu_map_ops = {
.map_free = htab_map_free,
.map_get_next_key = htab_map_get_next_key,
.map_lookup_elem = htab_percpu_map_lookup_elem,
+ .map_lookup_and_delete_elem = htab_percpu_map_lookup_and_delete_elem,
.map_update_elem = htab_percpu_map_update_elem,
.map_delete_elem = htab_map_delete_elem,
.map_seq_show_elem = htab_percpu_map_seq_show_elem,
@@ -2096,6 +2175,7 @@ const struct bpf_map_ops htab_lru_percpu_map_ops = {
.map_free = htab_map_free,
.map_get_next_key = htab_map_get_next_key,
.map_lookup_elem = htab_lru_percpu_map_lookup_elem,
+ .map_lookup_and_delete_elem = htab_lru_percpu_map_lookup_and_delete_elem,
.map_update_elem = htab_lru_percpu_map_update_elem,
.map_delete_elem = htab_lru_map_delete_elem,
.map_seq_show_elem = htab_percpu_map_seq_show_elem,
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index c859bc46d06c..2634aa4a2f37 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1495,7 +1495,7 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
goto err_put;
}
- value_size = map->value_size;
+ value_size = bpf_map_value_size(map);
err = -ENOMEM;
value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
@@ -1505,6 +1505,18 @@ static int map_lookup_and_delete_elem(union bpf_attr *attr)
if (map->map_type == BPF_MAP_TYPE_QUEUE ||
map->map_type == BPF_MAP_TYPE_STACK) {
err = map->ops->map_pop_elem(map, value);
+ } else if (map->map_type == BPF_MAP_TYPE_HASH ||
+ map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
+ map->map_type == BPF_MAP_TYPE_LRU_HASH ||
+ map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH) {
+ if (!bpf_map_is_dev_bound(map)) {
+ bpf_disable_instrumentation();
+ rcu_read_lock();
+ err = map->ops->map_lookup_and_delete_elem(map, key, value);
+ rcu_read_unlock();
+ bpf_enable_instrumentation();
+ maybe_wait_bpf_programs(map);
+ }
} else {
err = -ENOTSUPP;
}
diff --git a/tools/testing/selftests/bpf/prog_tests/lookup_and_delete.c b/tools/testing/selftests/bpf/prog_tests/lookup_and_delete.c
new file mode 100644
index 000000000000..05123bbcdc1c
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/lookup_and_delete.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <test_progs.h>
+#include "test_lookup_and_delete.skel.h"
+
+#define START_VALUE 1234
+#define NEW_VALUE 4321
+#define MAX_ENTRIES 2
+
+static int duration;
+static int nr_cpus;
+
+static int fill_values(int map_fd)
+{
+ __u64 key, value = START_VALUE;
+ int err;
+
+ for (key = 1; key < MAX_ENTRIES + 1; key++) {
+ err = bpf_map_update_elem(map_fd, &key, &value, BPF_NOEXIST);
+ if (CHECK(err, "bpf_map_update_elem", "failed\n"))
+ return -1;
+ }
+
+ return 0;
+}
+
+static int fill_values_percpu(int map_fd)
+{
+ BPF_DECLARE_PERCPU(__u64, value);
+ int i, err;
+ u64 key;
+
+ for (i = 0; i < nr_cpus; i++)
+ bpf_percpu(value, i) = START_VALUE;
+
+ for (key = 1; key < MAX_ENTRIES + 1; key++) {
+ err = bpf_map_update_elem(map_fd, &key, value, BPF_NOEXIST);
+ if (CHECK(err, "bpf_map_update_elem", "failed\n"))
+ return -1;
+ }
+
+ return 0;
+}
+
+static struct test_lookup_and_delete *setup_prog(enum bpf_map_type map_type,
+ int *map_fd)
+{
+ struct test_lookup_and_delete *skel;
+ int err;
+
+ skel = test_lookup_and_delete__open();
+ if (CHECK(!skel, "test_lookup_and_delete__open", "failed\n"))
+ return NULL;
+
+ err = bpf_map__set_type(skel->maps.hash_map, map_type);
+ if (CHECK(err, "bpf_map__set_type", "failed\n"))
+ goto error;
+
+ err = test_lookup_and_delete__load(skel);
+ if (CHECK(err, "test_lookup_and_delete__load", "failed\n"))
+ goto error;
+
+ *map_fd = bpf_map__fd(skel->maps.hash_map);
+ if (CHECK(*map_fd < 0, "bpf_map__fd", "failed\n"))
+ goto error;
+
+ return skel;
+
+error:
+ test_lookup_and_delete__destroy(skel);
+ return NULL;
+}
+
+/* Triggers BPF program that updates map with given key and value */
+static int trigger_tp(struct test_lookup_and_delete *skel, __u64 key,
+ __u64 value)
+{
+ int err;
+
+ skel->bss->set_pid = getpid();
+ skel->bss->set_key = key;
+ skel->bss->set_value = value;
+
+ err = test_lookup_and_delete__attach(skel);
+ if (CHECK(err, "test_lookup_and_delete__attach", "failed\n"))
+ return -1;
+
+ syscall(__NR_getpgid);
+
+ test_lookup_and_delete__detach(skel);
+
+ return 0;
+}
+
+static void test_lookup_and_delete_hash(void)
+{
+ struct test_lookup_and_delete *skel;
+ __u64 key, value;
+ int map_fd, err;
+
+ /* Setup program and fill the map. */
+ skel = setup_prog(BPF_MAP_TYPE_HASH, &map_fd);
+ if (CHECK(!skel, "setup_prog", "failed\n"))
+ return;
+
+ err = fill_values(map_fd);
+ if (CHECK(err, "fill_values", "failed\n"))
+ goto cleanup;
+
+ /* Lookup and delete element. */
+ key = 1;
+ err = bpf_map_lookup_and_delete_elem(map_fd, &key, &value);
+ if (CHECK(err, "bpf_map_lookup_and_delete_elem", "failed, errno=%d\n",
+ errno))
+ goto cleanup;
+
+ /* Fetched value should match the initially set value. */
+ if (CHECK(value != START_VALUE, "bpf_map_lookup_and_delete_elem",
+ "value=%lld\n", value))
+ goto cleanup;
+
+ /* Check that the entry is non existent. */
+ err = bpf_map_lookup_elem(map_fd, &key, &value);
+ if (CHECK(!err, "bpf_map_lookup_elem", "succeded, should fail\n"))
+ goto cleanup;
+
+cleanup:
+ test_lookup_and_delete__destroy(skel);
+}
+
+static void test_lookup_and_delete_percpu_hash(void)
+{
+ struct test_lookup_and_delete *skel;
+ BPF_DECLARE_PERCPU(__u64, value);
+ int map_fd, err, i;
+ __u64 key, val;
+
+ /* Setup program and fill the map. */
+ skel = setup_prog(BPF_MAP_TYPE_PERCPU_HASH, &map_fd);
+ if (CHECK(!skel, "setup_prog", "failed\n"))
+ return;
+
+ err = fill_values_percpu(map_fd);
+ if (CHECK(err, "fill_values_percpu", "failed\n"))
+ goto cleanup;
+
+ /* Lookup and delete element. */
+ key = 1;
+ err = bpf_map_lookup_and_delete_elem(map_fd, &key, value);
+ if (CHECK(err, "bpf_map_lookup_and_delete_elem", "failed, errno=%d\n",
+ errno))
+ goto cleanup;
+
+ for (i = 0; i < nr_cpus; i++) {
+ if (bpf_percpu(value, i))
+ val = bpf_percpu(value, i);
+ }
+
+ /* Fetched value should match the initially set value. */
+ if (CHECK(val != START_VALUE, "bpf_map_lookup_and_delete_elem",
+ "val=%lld\n", val))
+ goto cleanup;
+
+ /* Check that the entry is non existent. */
+ err = bpf_map_lookup_elem(map_fd, &key, value);
+ if (CHECK(!err, "bpf_map_lookup_elem", "succeded, should fail\n"))
+ goto cleanup;
+
+cleanup:
+ test_lookup_and_delete__destroy(skel);
+}
+
+static void test_lookup_and_delete_lru_hash(void)
+{
+ struct test_lookup_and_delete *skel;
+ __u64 key, value;
+ int map_fd, err;
+
+ /* Setup program and fill the LRU map. */
+ skel = setup_prog(BPF_MAP_TYPE_LRU_HASH, &map_fd);
+ if (CHECK(!skel, "setup_prog", "failed\n"))
+ return;
+
+ err = fill_values(map_fd);
+ if (CHECK(err, "fill_values", "failed\n"))
+ goto cleanup;
+
+ /* Insert new element at key=3, should reuse LRU element. */
+ key = 3;
+ err = trigger_tp(skel, key, NEW_VALUE);
+ if (CHECK(err, "trigger_tp", "failed"))
+ goto cleanup;
+
+ /* Lookup and delete element 3. */
+ err = bpf_map_lookup_and_delete_elem(map_fd, &key, &value);
+ if (CHECK(err, "bpf_map_lookup_and_delete_elem", "failed, errno=%d\n",
+ errno))
+ goto cleanup;
+
+ /* Value should match the new value. */
+ if (CHECK(value != NEW_VALUE, "bpf_map_lookup_and_delete_elem",
+ "value=%lld\n", value))
+ goto cleanup;
+
+ /* Check that entries 3 and 1 are non existent. */
+ err = bpf_map_lookup_elem(map_fd, &key, &value);
+ if (CHECK(!err, "bpf_map_lookup_elem", "succeded, should fail\n"))
+ goto cleanup;
+
+ key = 1;
+ err = bpf_map_lookup_elem(map_fd, &key, &value);
+ if (CHECK(!err, "bpf_map_lookup_elem", "succeded, should fail\n"))
+ goto cleanup;
+
+cleanup:
+ test_lookup_and_delete__destroy(skel);
+}
+
+static void test_lookup_and_delete_lru_percpu_hash(void)
+{
+ struct test_lookup_and_delete *skel;
+ BPF_DECLARE_PERCPU(__u64, value);
+ int map_fd, err, i;
+ __u64 key, val;
+
+ /* Setup program and fill the LRU map. */
+ skel = setup_prog(BPF_MAP_TYPE_LRU_PERCPU_HASH, &map_fd);
+ if (CHECK(!skel, "setup_prog", "failed\n"))
+ return;
+
+ err = fill_values_percpu(map_fd);
+ if (CHECK(err, "fill_values_percpu", "failed\n"))
+ goto cleanup;
+
+ /* Insert new element at key=3, should reuse LRU element. */
+ key = 3;
+ err = trigger_tp(skel, key, NEW_VALUE);
+ if (CHECK(err, "trigger_tp", "failed"))
+ goto cleanup;
+
+ /* Lookup and delete element 3. */
+ err = bpf_map_lookup_and_delete_elem(map_fd, &key, &value);
+ if (CHECK(err, "bpf_map_lookup_and_delete_elem", "failed, errno=%d\n",
+ errno))
+ goto cleanup;
+
+ for (i = 0; i < nr_cpus; i++) {
+ if (bpf_percpu(value, i))
+ val = bpf_percpu(value, i);
+ }
+
+ /* Value should match the new value. */
+ if (CHECK(val != NEW_VALUE, "bpf_map_lookup_and_delete_elem",
+ "val=%lld\n", val))
+ goto cleanup;
+
+ /* Check that entries 3 and 1 are non existent. */
+ err = bpf_map_lookup_elem(map_fd, &key, &value);
+ if (CHECK(!err, "bpf_map_lookup_elem", "succeded, should fail\n"))
+ goto cleanup;
+
+ key = 1;
+ err = bpf_map_lookup_elem(map_fd, &key, &value);
+ if (CHECK(!err, "bpf_map_lookup_elem", "succeded, should fail\n"))
+ goto cleanup;
+
+cleanup:
+ test_lookup_and_delete__destroy(skel);
+}
+
+void test_lookup_and_delete(void)
+{
+ nr_cpus = bpf_num_possible_cpus();
+
+ if (test__start_subtest("lookup_and_delete"))
+ test_lookup_and_delete_hash();
+ if (test__start_subtest("lookup_and_delete_percpu"))
+ test_lookup_and_delete_percpu_hash();
+ if (test__start_subtest("lookup_and_delete_lru"))
+ test_lookup_and_delete_lru_hash();
+ if (test__start_subtest("lookup_and_delete_lru_percpu"))
+ test_lookup_and_delete_lru_percpu_hash();
+}
diff --git a/tools/testing/selftests/bpf/progs/test_lookup_and_delete.c b/tools/testing/selftests/bpf/progs/test_lookup_and_delete.c
new file mode 100644
index 000000000000..eb19de8bb415
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_lookup_and_delete.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+__u32 set_pid;
+__u64 set_key;
+__u64 set_value;
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, 2);
+ __type(key, __u64);
+ __type(value, __u64);
+} hash_map SEC(".maps");
+
+SEC("tp/syscalls/sys_enter_getpgid")
+int bpf_lookup_and_delete_test(const void *ctx)
+{
+ if (set_pid == bpf_get_current_pid_tgid() >> 32)
+ bpf_map_update_elem(&hash_map, &set_key, &set_value, BPF_NOEXIST);
+
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_lru_map.c b/tools/testing/selftests/bpf/test_lru_map.c
index 6a5349f9eb14..f33fb6de76bc 100644
--- a/tools/testing/selftests/bpf/test_lru_map.c
+++ b/tools/testing/selftests/bpf/test_lru_map.c
@@ -231,6 +231,14 @@ static void test_lru_sanity0(int map_type, int map_flags)
assert(bpf_map_lookup_elem(lru_map_fd, &key, value) == -1 &&
errno == ENOENT);
+ /* lookup elem key=3 and delete it, than check it doesn't exist */
+ key = 1;
+ assert(!bpf_map_lookup_and_delete_elem(lru_map_fd, &key, &value));
+ assert(value[0] == 1234);
+
+ /* remove the same element from the expected map */
+ assert(!bpf_map_delete_elem(expected_map_fd, &key));
+
assert(map_equal(lru_map_fd, expected_map_fd));
close(expected_map_fd);
diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
index 51adc42b2b40..dbd5f95e8bde 100644
--- a/tools/testing/selftests/bpf/test_maps.c
+++ b/tools/testing/selftests/bpf/test_maps.c
@@ -65,6 +65,13 @@ static void test_hashmap(unsigned int task, void *data)
assert(bpf_map_lookup_elem(fd, &key, &value) == 0 && value == 1234);
key = 2;
+ value = 1234;
+ /* Insert key=2 element. */
+ assert(bpf_map_update_elem(fd, &key, &value, BPF_ANY) == 0);
+
+ /* Check that key=2 matches the value and delete it */
+ assert(bpf_map_lookup_and_delete_elem(fd, &key, &value) == 0 && value == 1234);
+
/* Check that key=2 is not found. */
assert(bpf_map_lookup_elem(fd, &key, &value) == -1 && errno == ENOENT);
@@ -164,8 +171,18 @@ static void test_hashmap_percpu(unsigned int task, void *data)
key = 1;
/* Insert key=1 element. */
- assert(!(expected_key_mask & key));
assert(bpf_map_update_elem(fd, &key, value, BPF_ANY) == 0);
+
+ /* Lookup and delete elem key=1 and check value. */
+ assert(bpf_map_lookup_and_delete_elem(fd, &key, value) == 0 &&
+ bpf_percpu(value, 0) == 100);
+
+ for (i = 0; i < nr_cpus; i++)
+ bpf_percpu(value, i) = i + 100;
+
+ /* Insert key=1 element which should not exist. */
+ assert(!(expected_key_mask & key));
+ assert(bpf_map_update_elem(fd, &key, value, BPF_NOEXIST) == 0);
expected_key_mask |= key;
/* BPF_NOEXIST means add new element if it doesn't exist. */
--
2.26.2
