From 16b4d3e2fb24aac3e68a8d86e3bc5e302e1b5cb7 Mon Sep 17 00:00:00 2001 From: Mykyta Yatsenko Date: Fri, 5 Jun 2026 04:41:21 -0700 Subject: bpf: Implement resizable hashmap basic functions Use rhashtable_lookup_likely() for lookups, rhashtable_remove_fast() for deletes, and rhashtable_lookup_get_insert_fast() for inserts. Updates modify values in place under RCU rather than allocating a new element and swapping the pointer (as regular htab does). This trades read consistency for performance: concurrent readers may see partial updates. BPF_F_LOCK support and special-field handling (timers, kptrs, etc.) follow in a later commit. Initialize rhashtable with bpf_mem_alloc element cache. Require BPF_F_NO_PREALLOC. Limit max_entries to 2^31. Free elements via rhashtable_free_and_destroy(). Signed-off-by: Mykyta Yatsenko Link: https://lore.kernel.org/r/20260605-rhash-v7-4-5b8e05f8630d@meta.com Signed-off-by: Alexei Starovoitov --- include/uapi/linux/bpf.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index aec171ccb6ef..bed9b1b4d5ef 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1047,6 +1047,7 @@ enum bpf_map_type { BPF_MAP_TYPE_CGRP_STORAGE, BPF_MAP_TYPE_ARENA, BPF_MAP_TYPE_INSN_ARRAY, + BPF_MAP_TYPE_RHASH, __MAX_BPF_MAP_TYPE }; @@ -1545,6 +1546,11 @@ union bpf_attr { * * BPF_MAP_TYPE_ARENA - contains the address where user space * is going to mmap() the arena. It has to be page aligned. + * + * BPF_MAP_TYPE_RHASH - initial table size hint + * (nelem_hint). 0 = use rhashtable default. Must be + * <= min(max_entries, U16_MAX). Upper 32 bits reserved, + * must be zero. */ __u64 map_extra; -- cgit v1.2.3