From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Westphal Subject: [PATCH ipsec-next 5/6] xfrm: state: simplify rcu_read_unlock handling in two spots Date: Mon, 9 Jan 2017 14:20:49 +0100 Message-ID: <1483968050-788-6-git-send-email-fw@strlen.de> References: <1483968050-788-1-git-send-email-fw@strlen.de> Cc: Florian Westphal To: Return-path: Received: from Chamillionaire.breakpoint.cc ([146.0.238.67]:48776 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761579AbdAINUs (ORCPT ); Mon, 9 Jan 2017 08:20:48 -0500 In-Reply-To: <1483968050-788-1-git-send-email-fw@strlen.de> Sender: netdev-owner@vger.kernel.org List-ID: 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 --- 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 ee1309e2b8b5..0245df063bd7 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; } -- 2.7.3