From patchwork Thu Sep 21 19:42:35 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ilya Maximets X-Patchwork-Id: 13394420 X-Patchwork-Delegate: kuba@kernel.org Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 EFC6B18058 for ; Thu, 21 Sep 2023 19:42:29 +0000 (UTC) Received: from relay8-d.mail.gandi.net (relay8-d.mail.gandi.net [217.70.183.201]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6C061481D; Thu, 21 Sep 2023 12:42:27 -0700 (PDT) Received: by mail.gandi.net (Postfix) with ESMTPSA id 32ABE1BF203; Thu, 21 Sep 2023 19:42:22 +0000 (UTC) From: Ilya Maximets To: netdev@vger.kernel.org Cc: Jakub Kicinski , "David S. Miller" , Eric Dumazet , Paolo Abeni , linux-kernel@vger.kernel.org, dev@openvswitch.org, Pravin B Shelar , Eelco Chaudron , Ilya Maximets Subject: [PATCH net-next v2] openvswitch: reduce stack usage in do_execute_actions Date: Thu, 21 Sep 2023 21:42:35 +0200 Message-ID: <20230921194314.1976605-1-i.maximets@ovn.org> X-Mailer: git-send-email 2.41.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-GND-Sasl: i.maximets@ovn.org X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL, SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: kuba@kernel.org do_execute_actions() function can be called recursively multiple times while executing actions that require pipeline forking or recirculations. It may also be re-entered multiple times if the packet leaves openvswitch module and re-enters it through a different port. Currently, there is a 256-byte array allocated on stack in this function that is supposed to hold NSH header. Compilers tend to pre-allocate that space right at the beginning of the function: a88: 48 81 ec b0 01 00 00 sub $0x1b0,%rsp NSH is not a very common protocol, but the space is allocated on every recursive call or re-entry multiplying the wasted stack space. Move the stack allocation to push_nsh() function that is only used if NSH actions are actually present. push_nsh() is also a simple function without a possibility for re-entry, so the stack is returned right away. With this change the preallocated space is reduced by 256 B per call: b18: 48 81 ec b0 00 00 00 sub $0xb0,%rsp Signed-off-by: Ilya Maximets Reviewed-by: Eric Dumazet Reviewed-by: Eelco Chaudron echaudro@redhat.com Reviewed-by: Aaron Conole --- Version 2: - Added 'noinline_for_stack' to avoid potential inlining. [Eric] net/openvswitch/actions.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c index 5f8094acd056..6fcd7e2ca81f 100644 --- a/net/openvswitch/actions.c +++ b/net/openvswitch/actions.c @@ -311,11 +311,18 @@ static int push_eth(struct sk_buff *skb, struct sw_flow_key *key, return 0; } -static int push_nsh(struct sk_buff *skb, struct sw_flow_key *key, - const struct nshhdr *nh) +static noinline_for_stack int push_nsh(struct sk_buff *skb, + struct sw_flow_key *key, + const struct nlattr *a) { + u8 buffer[NSH_HDR_MAX_LEN]; + struct nshhdr *nh = (struct nshhdr *)buffer; int err; + err = nsh_hdr_from_nlattr(a, nh, NSH_HDR_MAX_LEN); + if (err) + return err; + err = nsh_push(skb, nh); if (err) return err; @@ -1439,17 +1446,9 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb, err = pop_eth(skb, key); break; - case OVS_ACTION_ATTR_PUSH_NSH: { - u8 buffer[NSH_HDR_MAX_LEN]; - struct nshhdr *nh = (struct nshhdr *)buffer; - - err = nsh_hdr_from_nlattr(nla_data(a), nh, - NSH_HDR_MAX_LEN); - if (unlikely(err)) - break; - err = push_nsh(skb, key, nh); + case OVS_ACTION_ATTR_PUSH_NSH: + err = push_nsh(skb, key, nla_data(a)); break; - } case OVS_ACTION_ATTR_POP_NSH: err = pop_nsh(skb, key);