On Fri, Aug 8, 2025 at 9:11 AM Leon Hwang <leon.hwang@xxxxxxxxx> wrote:
>
> On Fri Aug 8, 2025 at 1:20 AM +08, Alexei Starovoitov wrote:
> > On Tue, Aug 5, 2025 at 9:30 AM Leon Hwang <leon.hwang@xxxxxxxxx> wrote:
> >>
> >> Introduce support for the BPF_F_CPU flag in percpu_array maps to allow
> >> updating values for specified CPU or for all CPUs with a single value.
> >>
> >> This enhancement enables:
> >>
> >> * Efficient update of all CPUs using a single value when cpu == (u32)~0.
> >> * Targeted update or lookup for a specified CPU otherwise.
> >>
> >> The flag is passed via:
> >>
> >> * map_flags in bpf_percpu_array_update() along with embedded cpu field.
> >> * elem_flags in generic_map_update_batch() along with embedded cpu field.
> >>
> >> Signed-off-by: Leon Hwang <leon.hwang@xxxxxxxxx>
> >> ---
> >> include/linux/bpf.h | 3 +-
> >> include/uapi/linux/bpf.h | 6 +++
> >> kernel/bpf/arraymap.c | 54 ++++++++++++++++++------
> >> kernel/bpf/syscall.c | 77 +++++++++++++++++++++-------------
> >> tools/include/uapi/linux/bpf.h | 6 +++
> >> 5 files changed, 103 insertions(+), 43 deletions(-)
> >>
> >> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> >> index cc700925b802f..c17c45f797ed9 100644
> >> --- a/include/linux/bpf.h
> >> +++ b/include/linux/bpf.h
> >> @@ -2691,7 +2691,8 @@ int map_set_for_each_callback_args(struct bpf_verifier_env *env,
> >> struct bpf_func_state *callee);
> >>
> >> int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);
> >> -int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
> >> +int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value,
> >> + u64 flags);
> >> int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
> >> u64 flags);
> >> int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
> >> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> >> index 233de8677382e..67bc35e4d6a8d 100644
> >> --- a/include/uapi/linux/bpf.h
> >> +++ b/include/uapi/linux/bpf.h
> >> @@ -1372,6 +1372,12 @@ enum {
> >> BPF_NOEXIST = 1, /* create new element if it didn't exist */
> >> BPF_EXIST = 2, /* update existing element */
> >> BPF_F_LOCK = 4, /* spin_lock-ed map_lookup/map_update */
> >> + BPF_F_CPU = 8, /* map_update for percpu_array */
> >
> > only percpu_array?!
> > Aren't you doing it for percpu_hash too?
> >
>
> Only percpu_array in this patchset.
>
> I have no need to do it for percpu_hash.
You're missing the point. If we're adding the flag it should
work for all per-cpu maps. Both array and hash.
Same issue as with your other patch with common_attr.
We're not adding a feature that works for 1 out 10
commands/map types/whatever and doesn't work for the rest.
Flags/features have to be generic and consistent.
