From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steffen Klassert Subject: [PATCH 07/15] xfrm: state: simplify rcu_read_unlock handling in two spots Date: Wed, 1 Feb 2017 09:17:49 +0100 Message-ID: <1485937077-612-8-git-send-email-steffen.klassert@secunet.com> References: <1485937077-612-1-git-send-email-steffen.klassert@secunet.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Herbert Xu , Steffen Klassert , To: David Miller Return-path: Received: from a.mx.secunet.com ([62.96.220.36]:37088 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751787AbdBAISQ (ORCPT ); Wed, 1 Feb 2017 03:18:16 -0500 In-Reply-To: <1485937077-612-1-git-send-email-steffen.klassert@secunet.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Florian Westphal Instead of: if (foo) { unlock(); return bar(); } unlock(); do: unlock(); if (foo) return bar(); This is ok because rcu protected structure is only dereferenced before the conditional. Signed-off-by: Florian Westphal Signed-off-by: Steffen Klassert --- net/xfrm/xfrm_state.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index b5dad89..a62097e 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -231,17 +231,18 @@ static const struct xfrm_type *xfrm_get_type(u8 proto, unsigned short family) return NULL; typemap = afinfo->type_map; - type = typemap[proto]; + type = READ_ONCE(typemap[proto]); if (unlikely(type && !try_module_get(type->owner))) type = NULL; + + rcu_read_unlock(); + if (!type && !modload_attempted) { - rcu_read_unlock(); request_module("xfrm-type-%d-%d", family, proto); modload_attempted = 1; goto retry; } - rcu_read_unlock(); return type; } @@ -327,17 +328,17 @@ static struct xfrm_mode *xfrm_get_mode(unsigned int encap, int family) if (unlikely(afinfo == NULL)) return NULL; - mode = afinfo->mode_map[encap]; + mode = READ_ONCE(afinfo->mode_map[encap]); if (unlikely(mode && !try_module_get(mode->owner))) mode = NULL; + + rcu_read_unlock(); if (!mode && !modload_attempted) { - rcu_read_unlock(); request_module("xfrm-mode-%d-%d", family, encap); modload_attempted = 1; goto retry; } - rcu_read_unlock(); return mode; } -- 1.9.1