ACK: [SRU][Focal][PATCH] Revert "bpf: Zero-fill re-used per-cpu map element"
Kleber Souza
kleber.souza at canonical.com
Mon Dec 7 09:57:28 UTC 2020
On 04.12.20 19:47, Kamal Mostafa wrote:
> BugLink: https://bugs.launchpad.net/bugs/1906866
>
> This reverts commit d946d4ddd6af531398201e7ce8f73bd1d8a98e2a.
>
> Reported upstream:
> https://lore.kernel.org/stable/20201204182846.27110-1-kamal@canonical.com/T/#u
>
> This v5.4.78 commit breaks the tools/testing/selftests/bpf build:
>
> [linux-5.4.y] c602ad2b52dc bpf: Zero-fill re-used per-cpu map element
> [focal] d946d4ddd6af bpf: Zero-fill re-used per-cpu map element
>
> Like this:
>
> prog_tests/map_init.c:5:10: fatal error: test_map_init.skel.h:
> No such file or directory
> 5 | #include "test_map_init.skel.h"
>
> Because tools/testing/selftests/bpf/Makefile in v5.4 does not have the
> "skeleton header generation" stuff (circa v5.6).
>
> Signed-off-by: Kamal Mostafa <kamal at canonical.com>
Thanks Kamal for the quick fix.
Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>
> ---
> kernel/bpf/hashtab.c | 30 +--
> .../selftests/bpf/prog_tests/map_init.c | 214 ------------------
> .../selftests/bpf/progs/test_map_init.c | 33 ---
> 3 files changed, 2 insertions(+), 275 deletions(-)
> delete mode 100644 tools/testing/selftests/bpf/prog_tests/map_init.c
> delete mode 100644 tools/testing/selftests/bpf/progs/test_map_init.c
>
> diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
> index 03a67583f6fb..728ffec52cf3 100644
> --- a/kernel/bpf/hashtab.c
> +++ b/kernel/bpf/hashtab.c
> @@ -709,32 +709,6 @@ static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,
> }
> }
>
> -static void pcpu_init_value(struct bpf_htab *htab, void __percpu *pptr,
> - void *value, bool onallcpus)
> -{
> - /* When using prealloc and not setting the initial value on all cpus,
> - * zero-fill element values for other cpus (just as what happens when
> - * not using prealloc). Otherwise, bpf program has no way to ensure
> - * known initial values for cpus other than current one
> - * (onallcpus=false always when coming from bpf prog).
> - */
> - if (htab_is_prealloc(htab) && !onallcpus) {
> - u32 size = round_up(htab->map.value_size, 8);
> - int current_cpu = raw_smp_processor_id();
> - int cpu;
> -
> - for_each_possible_cpu(cpu) {
> - if (cpu == current_cpu)
> - bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value,
> - size);
> - else
> - memset(per_cpu_ptr(pptr, cpu), 0, size);
> - }
> - } else {
> - pcpu_copy_value(htab, pptr, value, onallcpus);
> - }
> -}
> -
> static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab)
> {
> return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS &&
> @@ -805,7 +779,7 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
> }
> }
>
> - pcpu_init_value(htab, pptr, value, onallcpus);
> + pcpu_copy_value(htab, pptr, value, onallcpus);
>
> if (!prealloc)
> htab_elem_set_ptr(l_new, key_size, pptr);
> @@ -1101,7 +1075,7 @@ static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
> pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
> value, onallcpus);
> } else {
> - pcpu_init_value(htab, htab_elem_get_ptr(l_new, key_size),
> + pcpu_copy_value(htab, htab_elem_get_ptr(l_new, key_size),
> value, onallcpus);
> hlist_nulls_add_head_rcu(&l_new->hash_node, head);
> l_new = NULL;
> diff --git a/tools/testing/selftests/bpf/prog_tests/map_init.c b/tools/testing/selftests/bpf/prog_tests/map_init.c
> deleted file mode 100644
> index 14a31109dd0e..000000000000
> --- a/tools/testing/selftests/bpf/prog_tests/map_init.c
> +++ /dev/null
> @@ -1,214 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0-only
> -/* Copyright (c) 2020 Tessares SA <http://www.tessares.net> */
> -
> -#include <test_progs.h>
> -#include "test_map_init.skel.h"
> -
> -#define TEST_VALUE 0x1234
> -#define FILL_VALUE 0xdeadbeef
> -
> -static int nr_cpus;
> -static int duration;
> -
> -typedef unsigned long long map_key_t;
> -typedef unsigned long long map_value_t;
> -typedef struct {
> - map_value_t v; /* padding */
> -} __bpf_percpu_val_align pcpu_map_value_t;
> -
> -
> -static int map_populate(int map_fd, int num)
> -{
> - pcpu_map_value_t value[nr_cpus];
> - int i, err;
> - map_key_t key;
> -
> - for (i = 0; i < nr_cpus; i++)
> - bpf_percpu(value, i) = FILL_VALUE;
> -
> - for (key = 1; key <= num; key++) {
> - err = bpf_map_update_elem(map_fd, &key, value, BPF_NOEXIST);
> - if (!ASSERT_OK(err, "bpf_map_update_elem"))
> - return -1;
> - }
> -
> - return 0;
> -}
> -
> -static struct test_map_init *setup(enum bpf_map_type map_type, int map_sz,
> - int *map_fd, int populate)
> -{
> - struct test_map_init *skel;
> - int err;
> -
> - skel = test_map_init__open();
> - if (!ASSERT_OK_PTR(skel, "skel_open"))
> - return NULL;
> -
> - err = bpf_map__set_type(skel->maps.hashmap1, map_type);
> - if (!ASSERT_OK(err, "bpf_map__set_type"))
> - goto error;
> -
> - err = bpf_map__set_max_entries(skel->maps.hashmap1, map_sz);
> - if (!ASSERT_OK(err, "bpf_map__set_max_entries"))
> - goto error;
> -
> - err = test_map_init__load(skel);
> - if (!ASSERT_OK(err, "skel_load"))
> - goto error;
> -
> - *map_fd = bpf_map__fd(skel->maps.hashmap1);
> - if (CHECK(*map_fd < 0, "bpf_map__fd", "failed\n"))
> - goto error;
> -
> - err = map_populate(*map_fd, populate);
> - if (!ASSERT_OK(err, "map_populate"))
> - goto error_map;
> -
> - return skel;
> -
> -error_map:
> - close(*map_fd);
> -error:
> - test_map_init__destroy(skel);
> - return NULL;
> -}
> -
> -/* executes bpf program that updates map with key, value */
> -static int prog_run_insert_elem(struct test_map_init *skel, map_key_t key,
> - map_value_t value)
> -{
> - struct test_map_init__bss *bss;
> -
> - bss = skel->bss;
> -
> - bss->inKey = key;
> - bss->inValue = value;
> - bss->inPid = getpid();
> -
> - if (!ASSERT_OK(test_map_init__attach(skel), "skel_attach"))
> - return -1;
> -
> - /* Let tracepoint trigger */
> - syscall(__NR_getpgid);
> -
> - test_map_init__detach(skel);
> -
> - return 0;
> -}
> -
> -static int check_values_one_cpu(pcpu_map_value_t *value, map_value_t expected)
> -{
> - int i, nzCnt = 0;
> - map_value_t val;
> -
> - for (i = 0; i < nr_cpus; i++) {
> - val = bpf_percpu(value, i);
> - if (val) {
> - if (CHECK(val != expected, "map value",
> - "unexpected for cpu %d: 0x%llx\n", i, val))
> - return -1;
> - nzCnt++;
> - }
> - }
> -
> - if (CHECK(nzCnt != 1, "map value", "set for %d CPUs instead of 1!\n",
> - nzCnt))
> - return -1;
> -
> - return 0;
> -}
> -
> -/* Add key=1 elem with values set for all CPUs
> - * Delete elem key=1
> - * Run bpf prog that inserts new key=1 elem with value=0x1234
> - * (bpf prog can only set value for current CPU)
> - * Lookup Key=1 and check value is as expected for all CPUs:
> - * value set by bpf prog for one CPU, 0 for all others
> - */
> -static void test_pcpu_map_init(void)
> -{
> - pcpu_map_value_t value[nr_cpus];
> - struct test_map_init *skel;
> - int map_fd, err;
> - map_key_t key;
> -
> - /* max 1 elem in map so insertion is forced to reuse freed entry */
> - skel = setup(BPF_MAP_TYPE_PERCPU_HASH, 1, &map_fd, 1);
> - if (!ASSERT_OK_PTR(skel, "prog_setup"))
> - return;
> -
> - /* delete element so the entry can be re-used*/
> - key = 1;
> - err = bpf_map_delete_elem(map_fd, &key);
> - if (!ASSERT_OK(err, "bpf_map_delete_elem"))
> - goto cleanup;
> -
> - /* run bpf prog that inserts new elem, re-using the slot just freed */
> - err = prog_run_insert_elem(skel, key, TEST_VALUE);
> - if (!ASSERT_OK(err, "prog_run_insert_elem"))
> - goto cleanup;
> -
> - /* check that key=1 was re-created by bpf prog */
> - err = bpf_map_lookup_elem(map_fd, &key, value);
> - if (!ASSERT_OK(err, "bpf_map_lookup_elem"))
> - goto cleanup;
> -
> - /* and has expected values */
> - check_values_one_cpu(value, TEST_VALUE);
> -
> -cleanup:
> - test_map_init__destroy(skel);
> -}
> -
> -/* Add key=1 and key=2 elems with values set for all CPUs
> - * Run bpf prog that inserts new key=3 elem
> - * (only for current cpu; other cpus should have initial value = 0)
> - * Lookup Key=1 and check value is as expected for all CPUs
> - */
> -static void test_pcpu_lru_map_init(void)
> -{
> - pcpu_map_value_t value[nr_cpus];
> - struct test_map_init *skel;
> - int map_fd, err;
> - map_key_t key;
> -
> - /* Set up LRU map with 2 elements, values filled for all CPUs.
> - * With these 2 elements, the LRU map is full
> - */
> - skel = setup(BPF_MAP_TYPE_LRU_PERCPU_HASH, 2, &map_fd, 2);
> - if (!ASSERT_OK_PTR(skel, "prog_setup"))
> - return;
> -
> - /* run bpf prog that inserts new key=3 element, re-using LRU slot */
> - key = 3;
> - err = prog_run_insert_elem(skel, key, TEST_VALUE);
> - if (!ASSERT_OK(err, "prog_run_insert_elem"))
> - goto cleanup;
> -
> - /* check that key=3 replaced one of earlier elements */
> - err = bpf_map_lookup_elem(map_fd, &key, value);
> - if (!ASSERT_OK(err, "bpf_map_lookup_elem"))
> - goto cleanup;
> -
> - /* and has expected values */
> - check_values_one_cpu(value, TEST_VALUE);
> -
> -cleanup:
> - test_map_init__destroy(skel);
> -}
> -
> -void test_map_init(void)
> -{
> - nr_cpus = bpf_num_possible_cpus();
> - if (nr_cpus <= 1) {
> - printf("%s:SKIP: >1 cpu needed for this test\n", __func__);
> - test__skip();
> - return;
> - }
> -
> - if (test__start_subtest("pcpu_map_init"))
> - test_pcpu_map_init();
> - if (test__start_subtest("pcpu_lru_map_init"))
> - test_pcpu_lru_map_init();
> -}
> diff --git a/tools/testing/selftests/bpf/progs/test_map_init.c b/tools/testing/selftests/bpf/progs/test_map_init.c
> deleted file mode 100644
> index c89d28ead673..000000000000
> --- a/tools/testing/selftests/bpf/progs/test_map_init.c
> +++ /dev/null
> @@ -1,33 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -/* Copyright (c) 2020 Tessares SA <http://www.tessares.net> */
> -
> -#include "vmlinux.h"
> -#include <bpf/bpf_helpers.h>
> -
> -__u64 inKey = 0;
> -__u64 inValue = 0;
> -__u32 inPid = 0;
> -
> -struct {
> - __uint(type, BPF_MAP_TYPE_PERCPU_HASH);
> - __uint(max_entries, 2);
> - __type(key, __u64);
> - __type(value, __u64);
> -} hashmap1 SEC(".maps");
> -
> -
> -SEC("tp/syscalls/sys_enter_getpgid")
> -int sysenter_getpgid(const void *ctx)
> -{
> - /* Just do it for once, when called from our own test prog. This
> - * ensures the map value is only updated for a single CPU.
> - */
> - int cur_pid = bpf_get_current_pid_tgid() >> 32;
> -
> - if (cur_pid == inPid)
> - bpf_map_update_elem(&hashmap1, &inKey, &inValue, BPF_NOEXIST);
> -
> - return 0;
> -}
> -
> -char _license[] SEC("license") = "GPL";
>
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