From 6940fab84b826175cf90d48d0e3da1b76518f5b4 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 12 Aug 2015 09:41:40 +0200 Subject: [PATCH] tcg: add memory barriers in page_find_alloc accesses page_find is reading the radix tree outside all locks, so it has to use the RCU primitives. It does not need RCU critical sections because the PageDescs are never removed, so there is never a need to wait for the end of code sections that use a PageDesc. Signed-off-by: Paolo Bonzini --- translate-all.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/translate-all.c b/translate-all.c index 37bb56ca42..5329982518 100644 --- a/translate-all.c +++ b/translate-all.c @@ -431,26 +431,26 @@ static PageDesc *page_find_alloc(tb_page_addr_t index, int alloc) /* Level 2..N-1. */ for (i = V_L1_SHIFT / V_L2_BITS - 1; i > 0; i--) { - void **p = *lp; + void **p = atomic_rcu_read(lp); if (p == NULL) { if (!alloc) { return NULL; } p = g_new0(void *, V_L2_SIZE); - *lp = p; + atomic_rcu_set(lp, p); } lp = p + ((index >> (i * V_L2_BITS)) & (V_L2_SIZE - 1)); } - pd = *lp; + pd = atomic_rcu_read(lp); if (pd == NULL) { if (!alloc) { return NULL; } pd = g_new0(PageDesc, V_L2_SIZE); - *lp = pd; + atomic_rcu_set(lp, pd); } return pd + (index & (V_L2_SIZE - 1));