From 4762fb980465463734f02c67c67f40beb8903f73 Mon Sep 17 00:00:00 2001 From: Jan Stancek Date: Wed, 11 Feb 2015 14:06:23 +0100 Subject: [PATCH] ipv6: fix possible deadlock in ip6_fl_purge / ip6_fl_gc Use spin_lock_bh in ip6_fl_purge() to prevent following potentially deadlock scenario between ip6_fl_purge() and ip6_fl_gc() timer. ================================= [ INFO: inconsistent lock state ] 3.19.0 #1 Not tainted --------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/5/0 [HC0[0]:SC1[1]:HE1:SE0] takes: (ip6_fl_lock){+.?...}, at: [] ip6_fl_gc+0x2d/0x180 {SOFTIRQ-ON-W} state was registered at: [] __lock_acquire+0x4a0/0x10b0 [] lock_acquire+0xc4/0x2b0 [] _raw_spin_lock+0x3d/0x80 [] ip6_flowlabel_net_exit+0x28/0x110 [] ops_exit_list.isra.1+0x39/0x60 [] cleanup_net+0x100/0x1e0 [] process_one_work+0x20a/0x830 [] worker_thread+0x11b/0x460 [] kthread+0x104/0x120 [] ret_from_fork+0x7c/0xb0 irq event stamp: 84640 hardirqs last enabled at (84640): [] _raw_spin_unlock_irq+0x30/0x50 hardirqs last disabled at (84639): [] _raw_spin_lock_irq+0x1f/0x80 softirqs last enabled at (84628): [] _local_bh_enable+0x21/0x50 softirqs last disabled at (84629): [] irq_exit+0x12d/0x150 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(ip6_fl_lock); lock(ip6_fl_lock); *** DEADLOCK *** Signed-off-by: Jan Stancek Signed-off-by: David S. Miller --- net/ipv6/ip6_flowlabel.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c index 2f780cba6e12..f45d6db50a45 100644 --- a/net/ipv6/ip6_flowlabel.c +++ b/net/ipv6/ip6_flowlabel.c @@ -172,7 +172,7 @@ static void __net_exit ip6_fl_purge(struct net *net) { int i; - spin_lock(&ip6_fl_lock); + spin_lock_bh(&ip6_fl_lock); for (i = 0; i <= FL_HASH_MASK; i++) { struct ip6_flowlabel *fl; struct ip6_flowlabel __rcu **flp; @@ -190,7 +190,7 @@ static void __net_exit ip6_fl_purge(struct net *net) flp = &fl->next; } } - spin_unlock(&ip6_fl_lock); + spin_unlock_bh(&ip6_fl_lock); } static struct ip6_flowlabel *fl_intern(struct net *net, -- 2.39.5