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Merge branch 'bpf-cpumap-improve-error-propagation-in-cpu_map_update_elem'

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Kohei Enju says:

====================
bpf: cpumap: improve error propagation in cpu_map_update_elem()

This series improves error propagation in cpumap and adds selftests that
cover the failure cases.

Currently, failures returned from __cpu_map_entry_alloc() are ignored
and always converted to -ENOMEM by cpu_map_update_elem(). This series
ensures the correct error propagation and adds selftests.

Changes:
  v2:
    - send to bpf-next, not to bpf
    - drop Fixes: tag
  v1: https://lore.kernel.org/bpf/20251128160504.57844-1-enjuk@amazon.com/
====================

Link: https://patch.msgid.link/20251208131449.73036-1-enjuk@amazon.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2025-12-09 23:53:27 -08:00
commit c93c124600
2 changed files with 30 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
kernel/bpf/cpumap.c
View File

@ -430,7 +430,7 @@ static struct bpf_cpu_map_entry *
__cpu_map_entry_alloc(struct bpf_map *map, struct bpf_cpumap_val *value,
u32 cpu)
{
int numa, err, i, fd = value->bpf_prog.fd;
int numa, err = -ENOMEM, i, fd = value->bpf_prog.fd;
gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
struct bpf_cpu_map_entry *rcpu;
struct xdp_bulk_queue *bq;
@ -440,7 +440,7 @@ __cpu_map_entry_alloc(struct bpf_map *map, struct bpf_cpumap_val *value,
rcpu = bpf_map_kmalloc_node(map, sizeof(*rcpu), gfp | __GFP_ZERO, numa);
if (!rcpu)
return NULL;
return ERR_PTR(err);
/* Alloc percpu bulkq */
rcpu->bulkq = bpf_map_alloc_percpu(map, sizeof(*rcpu->bulkq),
@ -468,16 +468,21 @@ __cpu_map_entry_alloc(struct bpf_map *map, struct bpf_cpumap_val *value,
rcpu->value.qsize = value->qsize;
gro_init(&rcpu->gro);
if (fd > 0 && __cpu_map_load_bpf_program(rcpu, map, fd))
goto free_ptr_ring;
if (fd > 0) {
err = __cpu_map_load_bpf_program(rcpu, map, fd);
if (err)
goto free_ptr_ring;
}
/* Setup kthread */
init_completion(&rcpu->kthread_running);
rcpu->kthread = kthread_create_on_node(cpu_map_kthread_run, rcpu, numa,
"cpumap/%d/map:%d", cpu,
map->id);
if (IS_ERR(rcpu->kthread))
if (IS_ERR(rcpu->kthread)) {
err = PTR_ERR(rcpu->kthread);
goto free_prog;
}
/* Make sure kthread runs on a single CPU */
kthread_bind(rcpu->kthread, cpu);
@ -503,7 +508,7 @@ __cpu_map_entry_alloc(struct bpf_map *map, struct bpf_cpumap_val *value,
free_percpu(rcpu->bulkq);
free_rcu:
kfree(rcpu);
return NULL;
return ERR_PTR(err);
}
static void __cpu_map_entry_free(struct work_struct *work)
@ -596,8 +601,8 @@ static long cpu_map_update_elem(struct bpf_map *map, void *key, void *value,
} else {
/* Updating qsize cause re-allocation of bpf_cpu_map_entry */
rcpu = __cpu_map_entry_alloc(map, &cpumap_value, key_cpu);
if (!rcpu)
return -ENOMEM;
if (IS_ERR(rcpu))
return PTR_ERR(rcpu);
}
rcu_read_lock();
__cpu_map_entry_replace(cmap, key_cpu, rcpu);

19
tools/testing/selftests/bpf/prog_tests/xdp_cpumap_attach.c
View File

@ -18,7 +18,7 @@ static void test_xdp_with_cpumap_helpers(void)
struct bpf_cpumap_val val = {
.qsize = 192,
};
int err, prog_fd, prog_redir_fd, map_fd;
int err, prog_fd, prog_redir_fd, map_fd, bad_fd;
struct nstoken *nstoken = NULL;
__u32 idx = 0;
@ -79,7 +79,22 @@ static void test_xdp_with_cpumap_helpers(void)
val.qsize = 192;
val.bpf_prog.fd = bpf_program__fd(skel->progs.xdp_dummy_prog);
err = bpf_map_update_elem(map_fd, &idx, &val, 0);
ASSERT_NEQ(err, 0, "Add non-BPF_XDP_CPUMAP program to cpumap entry");
ASSERT_EQ(err, -EINVAL, "Add non-BPF_XDP_CPUMAP program to cpumap entry");
/* Try to attach non-BPF file descriptor */
bad_fd = open("/dev/null", O_RDONLY);
ASSERT_GE(bad_fd, 0, "Open /dev/null for non-BPF fd");
val.bpf_prog.fd = bad_fd;
err = bpf_map_update_elem(map_fd, &idx, &val, 0);
ASSERT_EQ(err, -EINVAL, "Add non-BPF fd to cpumap entry");
/* Try to attach nonexistent file descriptor */
err = close(bad_fd);
ASSERT_EQ(err, 0, "Close non-BPF fd for nonexistent fd");
err = bpf_map_update_elem(map_fd, &idx, &val, 0);
ASSERT_EQ(err, -EBADF, "Add nonexistent fd to cpumap entry");
/* Try to attach BPF_XDP program with frags to cpumap when we have
* already loaded a BPF_XDP program on the map