This is a note to let you know that I've just added the patch titled
Revert "ipv6: grab rt->rt6i_ref before allocating pcpu rt"
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: revert-ipv6-grab-rt-rt6i_ref-before-allocating-pcpu-rt.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 406eee2fdb71005f98a60da42867051f16a57953 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman gregkh@linuxfoundation.org Date: Wed, 27 Dec 2017 13:53:08 +0100 Subject: Revert "ipv6: grab rt->rt6i_ref before allocating pcpu rt"
From: Greg Kroah-Hartman gregkh@linuxfoundation.org
This reverts commit 9704f8147e88213f2fa580f713b42b08a4f1a7d2 which was upstream commit a94b9367e044ba672c9f4105eb1516ff6ff4948a.
Shouldn't have been here, sorry about that.
Reported-by: Chris Rankin rankincj@gmail.com Reported-by: Willy Tarreau w@1wt.eu Cc: Ido Schimmel idosch@idosch.org Cc: Ozgur ozgur@goosey.org Cc: Wei Wang weiwan@google.com Cc: Martin KaFai Lau kafai@fb.com Cc: Eric Dumazet edumazet@google.com Cc: David S. Miller davem@davemloft.net Cc: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv6/route.c | 58 +++++++++++++++++++++++++++---------------------------- 1 file changed, 29 insertions(+), 29 deletions(-)
--- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1055,6 +1055,7 @@ static struct rt6_info *rt6_get_pcpu_rou
static struct rt6_info *rt6_make_pcpu_route(struct rt6_info *rt) { + struct fib6_table *table = rt->rt6i_table; struct rt6_info *pcpu_rt, *prev, **p;
pcpu_rt = ip6_rt_pcpu_alloc(rt); @@ -1065,20 +1066,28 @@ static struct rt6_info *rt6_make_pcpu_ro return net->ipv6.ip6_null_entry; }
- dst_hold(&pcpu_rt->dst); - p = this_cpu_ptr(rt->rt6i_pcpu); - prev = cmpxchg(p, NULL, pcpu_rt); - if (prev) { - /* If someone did it before us, return prev instead */ - /* release refcnt taken by ip6_rt_pcpu_alloc() */ - dst_release_immediate(&pcpu_rt->dst); - /* release refcnt taken by above dst_hold() */ + read_lock_bh(&table->tb6_lock); + if (rt->rt6i_pcpu) { + p = this_cpu_ptr(rt->rt6i_pcpu); + prev = cmpxchg(p, NULL, pcpu_rt); + if (prev) { + /* If someone did it before us, return prev instead */ + dst_release_immediate(&pcpu_rt->dst); + pcpu_rt = prev; + } + } else { + /* rt has been removed from the fib6 tree + * before we have a chance to acquire the read_lock. + * In this case, don't brother to create a pcpu rt + * since rt is going away anyway. The next + * dst_check() will trigger a re-lookup. + */ dst_release_immediate(&pcpu_rt->dst); - dst_hold(&prev->dst); - pcpu_rt = prev; + pcpu_rt = rt; } - + dst_hold(&pcpu_rt->dst); rt6_dst_from_metrics_check(pcpu_rt); + read_unlock_bh(&table->tb6_lock); return pcpu_rt; }
@@ -1168,28 +1177,19 @@ redo_rt6_select: if (pcpu_rt) { read_unlock_bh(&table->tb6_lock); } else { - /* atomic_inc_not_zero() is needed when using rcu */ - if (atomic_inc_not_zero(&rt->rt6i_ref)) { - /* We have to do the read_unlock first - * because rt6_make_pcpu_route() may trigger - * ip6_dst_gc() which will take the write_lock. - * - * No dst_hold() on rt is needed because grabbing - * rt->rt6i_ref makes sure rt can't be released. - */ - read_unlock_bh(&table->tb6_lock); - pcpu_rt = rt6_make_pcpu_route(rt); - rt6_release(rt); - } else { - /* rt is already removed from tree */ - read_unlock_bh(&table->tb6_lock); - pcpu_rt = net->ipv6.ip6_null_entry; - dst_hold(&pcpu_rt->dst); - } + /* We have to do the read_unlock first + * because rt6_make_pcpu_route() may trigger + * ip6_dst_gc() which will take the write_lock. + */ + dst_hold(&rt->dst); + read_unlock_bh(&table->tb6_lock); + pcpu_rt = rt6_make_pcpu_route(rt); + dst_release(&rt->dst); }
trace_fib6_table_lookup(net, pcpu_rt, table->tb6_id, fl6); return pcpu_rt; + } } EXPORT_SYMBOL_GPL(ip6_pol_route);
Patches currently in stable-queue which might be from gregkh@linuxfoundation.org are
queue-4.14/x86-decoder-fix-and-update-the-opcodes-map.patch queue-4.14/tools-headers-sync-objtool-uapi-header.patch queue-4.14/objtool-fix-64-bit-build-on-32-bit-host.patch queue-4.14/revert-ipv6-grab-rt-rt6i_ref-before-allocating-pcpu-rt.patch queue-4.14/objtool-move-synced-files-to-their-original-relative-locations.patch queue-4.14/objtool-move-kernel-headers-code-sync-check-to-a-script.patch queue-4.14/objtool-fix-cross-build.patch