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bpf: Add zero_map_value to zero map value with special fields

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We need this helper to skip over special fields (bpf_spin_lock,
bpf_timer, kptrs) while zeroing a map value. Use the same logic as
copy_map_value but memset instead of memcpy.

Currently, the code zeroing map value memory does not have to deal with
special fields, hence this is a prerequisite for introducing such
support.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220904204145.3089-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Kumar Kartikeya Dwivedi 2022-09-04 22:41:16 +02:00 committed by Alexei Starovoitov
parent 6df4ea1ff0
commit cc48755808
1 changed files with 19 additions and 0 deletions
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19
include/linux/bpf.h
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@ -329,6 +329,25 @@ static inline void copy_map_value_long(struct bpf_map *map, void *dst, void *src
__copy_map_value(map, dst, src, true);
}
static inline void zero_map_value(struct bpf_map *map, void *dst)
{
u32 curr_off = 0;
int i;
if (likely(!map->off_arr)) {
memset(dst, 0, map->value_size);
return;
}
for (i = 0; i < map->off_arr->cnt; i++) {
u32 next_off = map->off_arr->field_off[i];
memset(dst + curr_off, 0, next_off - curr_off);
curr_off += map->off_arr->field_sz[i];
}
memset(dst + curr_off, 0, map->value_size - curr_off);
}
void copy_map_value_locked(struct bpf_map *map, void *dst, void *src,
bool lock_src);
void bpf_timer_cancel_and_free(void *timer);