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| author | Hou Tao <houtao1@huawei.com> | 2023-12-11 09:34:47 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-12-14 02:01:42 +0100 |
| commit | 2a0c6b41eec90c2a138ea8b574836744783c67ff (patch) | |
| tree | 733a6575e6f7d0cfef20deb2cd5e3d94c38c2469 /kernel | |
| parent | bpf: add small subset of SECURITY_PATH hooks to BPF sleepable_lsm_hooks list (diff) | |
| download | linux-2a0c6b41eec90c2a138ea8b574836744783c67ff.tar.xz linux-2a0c6b41eec90c2a138ea8b574836744783c67ff.zip | |
bpf: Update the comments in maybe_wait_bpf_programs()
Since commit 638e4b825d52 ("bpf: Allows per-cpu maps and map-in-map in
sleepable programs"), sleepable BPF program can also use map-in-map, but
maybe_wait_bpf_programs() doesn't handle it accordingly. The main reason
is that using synchronize_rcu_tasks_trace() to wait for the completions
of these sleepable BPF programs may incur a very long delay and
userspace may think it is hung, so the wait for sleepable BPF programs
is skipped. Update the comments in maybe_wait_bpf_programs() to reflect
the reason.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20231211083447.1921178-1-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/syscall.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 06320d9abf33..d63c1ed42412 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -142,9 +142,13 @@ static u32 bpf_map_value_size(const struct bpf_map *map) static void maybe_wait_bpf_programs(struct bpf_map *map) { - /* Wait for any running BPF programs to complete so that - * userspace, when we return to it, knows that all programs - * that could be running use the new map value. + /* Wait for any running non-sleepable BPF programs to complete so that + * userspace, when we return to it, knows that all non-sleepable + * programs that could be running use the new map value. For sleepable + * BPF programs, synchronize_rcu_tasks_trace() should be used to wait + * for the completions of these programs, but considering the waiting + * time can be very long and userspace may think it will hang forever, + * so don't handle sleepable BPF programs now. */ if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS || map->map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS) |