From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D56833C2785 for ; Tue, 8 Sep 2026 13:21:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788873713; cv=none; b=makjwR1gqdqmt0EJ26VQ76E8qwwA57jNZm1MiYxPr65sFGFNsli5Z+hyldvxJK8wXby75++yRlxrzPC2g+SBHv/+BFHgmodjxh1u1WOfHij4xpV/epwCA3Pee2MWlwN+5Zc7dvnff+peRvX1T9MGLWoEZoPV2zJOBh6MU43t9ik= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788873713; c=relaxed/simple; bh=2zpdRVylNKwYY376PfxqxnFKXaGYey9yvpcuTq26zYE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MLIDNwY4z0jMs2VGSg/ox488G76VUV8/z+YCV1o6dbSd6Z2c0snx11sgZ4sqMk93JJYyfH7qGVkJBs4yH2Occ/zaIEgD+oIBrx0K0d0cF69OqX4FxkqLoe/iB0bWmkdwI+KFx7dOvZLkoe2T1jzaj0/maAPLn0rDm3fLGNqfGq4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53CDB1F00A3F; Tue, 8 Sep 2026 13:21:51 +0000 (UTC) From: Sasha Levin To: stable@vger.kernel.org Cc: Jiri Olsa , Andrii Nakryiko , Sasha Levin Subject: [PATCH 6.12.y 2/5] bpf: Factor stackid_fastpath function from __bpf_get_stackid Date: Tue, 8 Sep 2026 09:21:45 -0400 Message-ID: <20260908132148.2288072-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260908132148.2288072-1-sashal@kernel.org> References: <2026090349-donor-crunching-700c@gregkh> <20260908132148.2288072-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jiri Olsa [ Upstream commit 0ca56befcffec3a6c9d1842eae06c74e1cf41f11 ] The new stackid_fastpath does the fast stack hash and trace check, that does not need new bucket allocation. It covers both just-ip and buildid code paths. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20260803210149.296496-3-jolsa@kernel.org Stable-dep-of: 15f1bd857466 ("bpf: Disable preemption in bpf_get_stackid") Signed-off-by: Sasha Levin --- kernel/bpf/stackmap.c | 43 ++++++++++++++++++++++++++++--------------- 1 file changed, 28 insertions(+), 15 deletions(-) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 0707bd2bd566c..605543688c81b 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -253,6 +253,7 @@ struct stackid { u32 len; u32 hash; u32 id; + bool hash_matches; }; static int stackid_init(struct stackid *stackid, struct bpf_map *map, @@ -273,28 +274,46 @@ static int stackid_init(struct stackid *stackid, struct bpf_map *map, stackid->hash = jhash2((u32 *)stackid->ips, stackid->len / sizeof(u32), 0); stackid->id = stackid->hash & (smap->n_buckets - 1); stackid->bucket = READ_ONCE(smap->buckets[stackid->id]); + stackid->hash_matches = stackid->bucket && stackid->bucket->hash == stackid->hash; return 0; } +static int stackid_fastpath(struct stackid *stackid, struct bpf_map *map, + struct perf_callchain_entry *trace, u64 flags) +{ + int err; + + err = stackid_init(stackid, map, trace, flags); + if (err) + return err; + + /* fast cmp */ + if (stackid->hash_matches && flags & BPF_F_FAST_STACK_CMP) + return stackid->id; + + if (stack_map_use_build_id(map)) + return -ENOENT; + if (stackid->hash_matches && stackid->bucket->nr == stackid->nr && + memcmp(stackid->bucket->data, stackid->ips, stackid->len) == 0) + return stackid->id; + if (stackid->bucket && !(flags & BPF_F_REUSE_STACKID)) + return -EEXIST; + return -ENOENT; +} + static long __bpf_get_stackid(struct stackid *stackid, struct bpf_map *map, struct perf_callchain_entry *trace, u64 flags) { struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); struct stack_map_bucket *new_bucket, *old_bucket; bool user = flags & BPF_F_USER_STACK; - bool hash_matches; u32 trace_len, i; int err; - err = stackid_init(stackid, map, trace, flags); - if (err) + err = stackid_fastpath(stackid, map, trace, flags); + if (err != -ENOENT) return err; - hash_matches = stackid->bucket && stackid->bucket->hash == stackid->hash; - /* fast cmp */ - if (hash_matches && flags & BPF_F_FAST_STACK_CMP) - return stackid->id; - if (stack_map_use_build_id(map)) { struct bpf_stack_build_id *id_offs; @@ -309,7 +328,7 @@ static long __bpf_get_stackid(struct stackid *stackid, struct bpf_map *map, id_offs[i].ip = stackid->ips[i]; stack_map_get_build_id_offset(id_offs, stackid->nr, user, false /* !may_fault */); trace_len = stackid->nr * sizeof(struct bpf_stack_build_id); - if (hash_matches && stackid->bucket->nr == stackid->nr && + if (stackid->hash_matches && stackid->bucket->nr == stackid->nr && memcmp(stackid->bucket->data, new_bucket->data, trace_len) == 0) { pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); return stackid->id; @@ -319,12 +338,6 @@ static long __bpf_get_stackid(struct stackid *stackid, struct bpf_map *map, return -EEXIST; } } else { - if (hash_matches && stackid->bucket->nr == stackid->nr && - memcmp(stackid->bucket->data, stackid->ips, stackid->len) == 0) - return stackid->id; - if (stackid->bucket && !(flags & BPF_F_REUSE_STACKID)) - return -EEXIST; - new_bucket = (struct stack_map_bucket *) pcpu_freelist_pop(&smap->freelist); if (unlikely(!new_bucket)) -- 2.53.0