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;a=summary
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@xxxxxxxxxxxxxxx> know about it.
>From 406eee2fdb71005f98a60da42867051f16a57953 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxx>
This reverts commit 9704f8147e88213f2fa580f713b42b08a4f1a7d2 which was
upstream commit a94b9367e044ba672c9f4105eb1516ff6ff4948a.
Shouldn't have been here, sorry about that.
Reported-by: Chris Rankin <rankincj@xxxxxxxxx>
Reported-by: Willy Tarreau <w@xxxxxx>
Cc: Ido Schimmel <idosch@xxxxxxxxxx>
Cc: Ozgur <ozgur@xxxxxxxxxx>
Cc: Wei Wang <weiwan@xxxxxxxxxx>
Cc: Martin KaFai Lau <kafai@xxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman gregkh@xxxxxxxxxxxxxxxxxxx
---
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@xxxxxxxxxxxxxxxxxxx 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