On Tue, Mar 10, 2020 at 06:47 PM CET, Lorenz Bauer wrote: > Migrate BPF_MAP_TYPE_QUEUE and BPF_MAP_TYPE_STACK to map_copy_value, > by introducing small wrappers that discard the (unused) key argument. > > Signed-off-by: Lorenz Bauer <lmb@xxxxxxxxxxxxxx> > --- > kernel/bpf/queue_stack_maps.c | 18 ++++++++++++++++++ > kernel/bpf/syscall.c | 5 +---- > 2 files changed, 19 insertions(+), 4 deletions(-) > > diff --git a/kernel/bpf/queue_stack_maps.c b/kernel/bpf/queue_stack_maps.c > index f697647ceb54..5c89b7583cd2 100644 > --- a/kernel/bpf/queue_stack_maps.c > +++ b/kernel/bpf/queue_stack_maps.c > @@ -262,11 +262,28 @@ static int queue_stack_map_get_next_key(struct bpf_map *map, void *key, > return -EINVAL; > } > > +/* Called from syscall */ > +static int queue_map_copy_value(struct bpf_map *map, void *key, void *value) > +{ > + (void)key; Alternatively, there's is the __always_unused compiler attribute from include/linux/compiler_attributes.h that seems to be in wide use. > + > + return queue_map_peek_elem(map, value); > +} > + > +/* Called from syscall */ > +static int stack_map_copy_value(struct bpf_map *map, void *key, void *value) > +{ > + (void)key; > + > + return stack_map_peek_elem(map, value); > +} > + > const struct bpf_map_ops queue_map_ops = { > .map_alloc_check = queue_stack_map_alloc_check, > .map_alloc = queue_stack_map_alloc, > .map_free = queue_stack_map_free, > .map_lookup_elem = queue_stack_map_lookup_elem, > + .map_copy_value = queue_map_copy_value, > .map_update_elem = queue_stack_map_update_elem, > .map_delete_elem = queue_stack_map_delete_elem, > .map_push_elem = queue_stack_map_push_elem, > @@ -280,6 +297,7 @@ const struct bpf_map_ops stack_map_ops = { > .map_alloc = queue_stack_map_alloc, > .map_free = queue_stack_map_free, > .map_lookup_elem = queue_stack_map_lookup_elem, > + .map_copy_value = stack_map_copy_value, > .map_update_elem = queue_stack_map_update_elem, > .map_delete_elem = queue_stack_map_delete_elem, > .map_push_elem = queue_stack_map_push_elem, > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index 6503824e81e9..20c6cdace275 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -218,10 +218,7 @@ static int bpf_map_copy_value(struct bpf_map *map, void *key, void *value, > return bpf_map_offload_lookup_elem(map, key, value); > > bpf_disable_instrumentation(); > - if (map->map_type == BPF_MAP_TYPE_QUEUE || > - map->map_type == BPF_MAP_TYPE_STACK) { > - err = map->ops->map_peek_elem(map, value); > - } else if (map->ops->map_copy_value) { > + if (map->ops->map_copy_value) { > err = map->ops->map_copy_value(map, key, value); > } else { > rcu_read_lock();