From 057996380a42bb64ccc04383cfa9c0ace4ea11f0 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Wed, 15 Jan 2020 10:43:04 -0800 Subject: bpf: Add batch ops to all htab bpf map htab can't use generic batch support due some problematic behaviours inherent to the data structre, i.e. while iterating the bpf map a concurrent program might delete the next entry that batch was about to use, in that case there's no easy solution to retrieve the next entry, the issue has been discussed multiple times (see [1] and [2]). The only way hmap can be traversed without the problem previously exposed is by making sure that the map is traversing entire buckets. This commit implements those strict requirements for hmap, the implementation follows the same interaction that generic support with some exceptions: - If keys/values buffer are not big enough to traverse a bucket, ENOSPC will be returned. - out_batch contains the value of the next bucket in the iteration, not the next key, but this is transparent for the user since the user should never use out_batch for other than bpf batch syscalls. This commits implements BPF_MAP_LOOKUP_BATCH and adds support for new command BPF_MAP_LOOKUP_AND_DELETE_BATCH. Note that for update/delete batch ops it is possible to use the generic implementations. [1] https://lore.kernel.org/bpf/20190724165803.87470-1-brianvv@google.com/ [2] https://lore.kernel.org/bpf/20190906225434.3635421-1-yhs@fb.com/ Signed-off-by: Yonghong Song Signed-off-by: Brian Vazquez Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200115184308.162644-6-brianvv@google.com --- kernel/bpf/syscall.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'kernel/bpf/syscall.c') diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index ce8244d1ba99..0d94d361379c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3310,7 +3310,8 @@ static int bpf_map_do_batch(const union bpf_attr *attr, if (IS_ERR(map)) return PTR_ERR(map); - if (cmd == BPF_MAP_LOOKUP_BATCH && + if ((cmd == BPF_MAP_LOOKUP_BATCH || + cmd == BPF_MAP_LOOKUP_AND_DELETE_BATCH) && !(map_get_sys_perms(map, f) & FMODE_CAN_READ)) { err = -EPERM; goto err_put; @@ -3324,6 +3325,8 @@ static int bpf_map_do_batch(const union bpf_attr *attr, if (cmd == BPF_MAP_LOOKUP_BATCH) BPF_DO_BATCH(map->ops->map_lookup_batch); + else if (cmd == BPF_MAP_LOOKUP_AND_DELETE_BATCH) + BPF_DO_BATCH(map->ops->map_lookup_and_delete_batch); else if (cmd == BPF_MAP_UPDATE_BATCH) BPF_DO_BATCH(map->ops->map_update_batch); else @@ -3434,6 +3437,10 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz case BPF_MAP_LOOKUP_BATCH: err = bpf_map_do_batch(&attr, uattr, BPF_MAP_LOOKUP_BATCH); break; + case BPF_MAP_LOOKUP_AND_DELETE_BATCH: + err = bpf_map_do_batch(&attr, uattr, + BPF_MAP_LOOKUP_AND_DELETE_BATCH); + break; case BPF_MAP_UPDATE_BATCH: err = bpf_map_do_batch(&attr, uattr, BPF_MAP_UPDATE_BATCH); break; -- cgit