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Mercier" , , , , , , , , , , , Cc: , In-Reply-To: <20261002161738.621133-3-tjmercier@google.com> References: <20261002161738.621133-1-tjmercier@google.com> <20261002161738.621133-3-tjmercier@google.com> X-Mailer: mkdraft (claude review draft; edit before sending) Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, Oct 02, 2026 at 09:17 AM T.J. Mercier wrote: > +static __always_inline struct htab_elem * > +__lookup_elem_raw(struct bpf_htab *htab, struct hlist_nulls_head *head, > + u32 hash, void *key, u32 key_size, > + struct hlist_nulls_node **out_n) > { > struct hlist_nulls_node *n; > struct htab_elem *l; > > - hlist_nulls_for_each_entry_rcu(l, n, head, hash_node) > - if (l->hash == hash && !memcmp(&l->key, key, key_size)) > - return l; > + if (htab_has_hash(htab)) { [...] > + unsigned long k = 0; > + > + memcpy(&k, key, key_size); My bot is saying that this will break 32-bit builds with FORTIFY_SOURCE. __htab_map_lookup_elem_u64() inlines all of it with key_size == 8. has_hash is a run-time load, so the compiler has to keep this branch and it's a memcpy of 8 bytes into 4 byte 'k'. fortify_memcpy_chk() will hit __write_overflow_field(). That's a build error in i386 and arm allmodconfig. has_hash is a compile time constant in __htab_map_lookup_elem_u32() and _u64(), just like key_size. Only htab_map_gen_lookup() emits them, so the map is BPF_MAP_TYPE_HASH, never LRU. Don't read it from htab in these two. pw-bot: cr