Merge branch 'linus' into locking/core, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 8 insertions, 2 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index a1f2830d8110..b5b47a26d4ec 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -476,12 +476,18 @@ u32 ip_idents_reserve(u32 hash, int segs)
 	atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ;
 	u32 old = ACCESS_ONCE(*p_tstamp);
 	u32 now = (u32)jiffies;
-	u32 delta = 0;
+	u32 new, delta = 0;
 
 	if (old != now && cmpxchg(p_tstamp, old, now) == old)
 		delta = prandom_u32_max(now - old);
 
-	return atomic_add_return(segs + delta, p_id) - segs;
+	/* Do not use atomic_add_return() as it makes UBSAN unhappy */
+	do {
+		old = (u32)atomic_read(p_id);
+		new = old + delta + segs;
+	} while (atomic_cmpxchg(p_id, old, new) != old);
+
+	return new - segs;
 }
 EXPORT_SYMBOL(ip_idents_reserve);