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Subject[PATCH 4.15 14/23] cls_u32: add missing RCU annotation.
Date
4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paolo Abeni <pabeni@redhat.com>


[ Upstream commit 058a6c033488494a6b1477b05fe8e1a16e344462 ]

In a couple of points of the control path, n->ht_down is currently
accessed without the required RCU annotation. The accesses are
safe, but sparse complaints. Since we already held the
rtnl lock, let use rtnl_dereference().

Fixes: a1b7c5fd7fe9 ("net: sched: add cls_u32 offload hooks for netdevs")
Fixes: de5df63228fc ("net: sched: cls_u32 changes to knode must appear atomic to readers")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sched/cls_u32.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -544,6 +544,7 @@ static void u32_remove_hw_knode(struct t
static int u32_replace_hw_knode(struct tcf_proto *tp, struct tc_u_knode *n,
u32 flags)
{
+ struct tc_u_hnode *ht = rtnl_dereference(n->ht_down);
struct tcf_block *block = tp->chain->block;
struct tc_cls_u32_offload cls_u32 = {};
bool skip_sw = tc_skip_sw(flags);
@@ -563,7 +564,7 @@ static int u32_replace_hw_knode(struct t
cls_u32.knode.sel = &n->sel;
cls_u32.knode.exts = &n->exts;
if (n->ht_down)
- cls_u32.knode.link_handle = n->ht_down->handle;
+ cls_u32.knode.link_handle = ht->handle;

err = tc_setup_cb_call(block, NULL, TC_SETUP_CLSU32, &cls_u32, skip_sw);
if (err < 0) {
@@ -840,8 +841,9 @@ static void u32_replace_knode(struct tcf
static struct tc_u_knode *u32_init_knode(struct tcf_proto *tp,
struct tc_u_knode *n)
{
- struct tc_u_knode *new;
+ struct tc_u_hnode *ht = rtnl_dereference(n->ht_down);
struct tc_u32_sel *s = &n->sel;
+ struct tc_u_knode *new;

new = kzalloc(sizeof(*n) + s->nkeys*sizeof(struct tc_u32_key),
GFP_KERNEL);
@@ -859,11 +861,11 @@ static struct tc_u_knode *u32_init_knode
new->fshift = n->fshift;
new->res = n->res;
new->flags = n->flags;
- RCU_INIT_POINTER(new->ht_down, n->ht_down);
+ RCU_INIT_POINTER(new->ht_down, ht);

/* bump reference count as long as we hold pointer to structure */
- if (new->ht_down)
- new->ht_down->refcnt++;
+ if (ht)
+ ht->refcnt++;

#ifdef CONFIG_CLS_U32_PERF
/* Statistics may be incremented by readers during update

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