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Message-ID: <CAOrHB_CnpcQoztqnfBkaDhTCK5nti8agtRmbbzZH+BfrPpiZ1g@mail.gmail.com>
Date: Thu, 24 Oct 2019 00:14:07 -0700
From: Pravin Shelar <pshelar@....org>
To: Tonghao Zhang <xiangxia.m.yue@...il.com>
Cc: Greg Rose <gvrose8192@...il.com>,
Linux Kernel Network Developers <netdev@...r.kernel.org>,
ovs dev <dev@...nvswitch.org>
Subject: Re: [PATCH net-next v4 08/10] net: openvswitch: fix possible memleak
on destroy flow-table
On Tue, Oct 22, 2019 at 7:35 PM Tonghao Zhang <xiangxia.m.yue@...il.com> wrote:
>
> On Tue, Oct 22, 2019 at 2:58 PM Pravin Shelar <pshelar@....org> wrote:
> >
...
> > > >
> > Sure, I can review it, Can you send the patch inlined in mail?
> >
> > Thanks.
> diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
> index 5df5182..5b20793 100644
> --- a/net/openvswitch/flow_table.c
> +++ b/net/openvswitch/flow_table.c
> @@ -257,10 +257,75 @@ static void flow_tbl_destroy_rcu_cb(struct rcu_head *rcu)
> __table_instance_destroy(ti);
> }
>
> -static void table_instance_destroy(struct table_instance *ti,
> - struct table_instance *ufid_ti,
> +static void tbl_mask_array_del_mask(struct flow_table *tbl,
> + struct sw_flow_mask *mask)
> +{
> + struct mask_array *ma = ovsl_dereference(tbl->mask_array);
> + int i, ma_count = READ_ONCE(ma->count);
> +
> + /* Remove the deleted mask pointers from the array */
> + for (i = 0; i < ma_count; i++) {
> + if (mask == ovsl_dereference(ma->masks[i]))
> + goto found;
> + }
> +
> + BUG();
> + return;
> +
> +found:
> + WRITE_ONCE(ma->count, ma_count -1);
> +
> + rcu_assign_pointer(ma->masks[i], ma->masks[ma_count -1]);
> + RCU_INIT_POINTER(ma->masks[ma_count -1], NULL);
> +
> + kfree_rcu(mask, rcu);
> +
> + /* Shrink the mask array if necessary. */
> + if (ma->max >= (MASK_ARRAY_SIZE_MIN * 2) &&
> + ma_count <= (ma->max / 3))
> + tbl_mask_array_realloc(tbl, ma->max / 2);
> +}
> +
> +/* Remove 'mask' from the mask list, if it is not needed any more. */
> +static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
> +{
> + if (mask) {
> + /* ovs-lock is required to protect mask-refcount and
> + * mask list.
> + */
> + ASSERT_OVSL();
> + BUG_ON(!mask->ref_count);
> + mask->ref_count--;
> +
> + if (!mask->ref_count)
> + tbl_mask_array_del_mask(tbl, mask);
> + }
> +}
> +
> +static void table_instance_remove(struct flow_table *table, struct
> sw_flow *flow)
> +{
> + struct table_instance *ti = ovsl_dereference(table->ti);
> + struct table_instance *ufid_ti = ovsl_dereference(table->ufid_ti);
> +
> + BUG_ON(table->count == 0);
> + hlist_del_rcu(&flow->flow_table.node[ti->node_ver]);
> + table->count--;
> + if (ovs_identifier_is_ufid(&flow->id)) {
> + hlist_del_rcu(&flow->ufid_table.node[ufid_ti->node_ver]);
> + table->ufid_count--;
> + }
> +
> + /* RCU delete the mask. 'flow->mask' is not NULLed, as it should be
> + * accessible as long as the RCU read lock is held.
> + */
> + flow_mask_remove(table, flow->mask);
> +}
> +
> +static void table_instance_destroy(struct flow_table *table,
> bool deferred)
> {
> + struct table_instance *ti = ovsl_dereference(table->ti);
> + struct table_instance *ufid_ti = ovsl_dereference(table->ufid_ti);
> int i;
>
> if (!ti)
> @@ -274,13 +339,9 @@ static void table_instance_destroy(struct
> table_instance *ti,
> struct sw_flow *flow;
> struct hlist_head *head = &ti->buckets[i];
> struct hlist_node *n;
> - int ver = ti->node_ver;
> - int ufid_ver = ufid_ti->node_ver;
>
> - hlist_for_each_entry_safe(flow, n, head, flow_table.node[ver]) {
> - hlist_del_rcu(&flow->flow_table.node[ver]);
> - if (ovs_identifier_is_ufid(&flow->id))
> - hlist_del_rcu(&flow->ufid_table.node[ufid_ver]);
> + hlist_for_each_entry_safe(flow, n, head,
> flow_table.node[ti->node_ver]) {
> + table_instance_remove(table, flow);
> ovs_flow_free(flow, deferred);
> }
> }
> @@ -300,12 +361,9 @@ static void table_instance_destroy(struct
> table_instance *ti,
> */
> void ovs_flow_tbl_destroy(struct flow_table *table)
> {
> - struct table_instance *ti = rcu_dereference_raw(table->ti);
> - struct table_instance *ufid_ti = rcu_dereference_raw(table->ufid_ti);
> -
> free_percpu(table->mask_cache);
> kfree_rcu(rcu_dereference_raw(table->mask_array), rcu);
> - table_instance_destroy(ti, ufid_ti, false);
> + table_instance_destroy(table, false);
> }
>
> struct sw_flow *ovs_flow_tbl_dump_next(struct table_instance *ti,
> @@ -400,10 +458,9 @@ static struct table_instance
> *table_instance_rehash(struct table_instance *ti,
> return new_ti;
> }
>
> -int ovs_flow_tbl_flush(struct flow_table *flow_table)
> +int ovs_flow_tbl_flush(struct flow_table *table)
> {
> - struct table_instance *old_ti, *new_ti;
> - struct table_instance *old_ufid_ti, *new_ufid_ti;
> + struct table_instance *new_ti, *new_ufid_ti;
>
> new_ti = table_instance_alloc(TBL_MIN_BUCKETS);
> if (!new_ti)
> @@ -412,16 +469,12 @@ int ovs_flow_tbl_flush(struct flow_table *flow_table)
> if (!new_ufid_ti)
> goto err_free_ti;
>
> - old_ti = ovsl_dereference(flow_table->ti);
> - old_ufid_ti = ovsl_dereference(flow_table->ufid_ti);
> + table_instance_destroy(table, true);
>
This would destroy running table causing unnecessary flow miss. Lets
keep current scheme of setting up new table before destroying current
one.
> - rcu_assign_pointer(flow_table->ti, new_ti);
> - rcu_assign_pointer(flow_table->ufid_ti, new_ufid_ti);
> - flow_table->last_rehash = jiffies;
> - flow_table->count = 0;
> - flow_table->ufid_count = 0;
> + rcu_assign_pointer(table->ti, new_ti);
> + rcu_assign_pointer(table->ufid_ti, new_ufid_ti);
> + table->last_rehash = jiffies;
>
> - table_instance_destroy(old_ti, old_ufid_ti, true);
> return 0;
>
> err_free_ti:
> @@ -700,69 +753,10 @@ static struct table_instance
> *table_instance_expand(struct table_instance *ti,
> return table_instance_rehash(ti, ti->n_buckets * 2, ufid);
> }
>
> -static void tbl_mask_array_del_mask(struct flow_table *tbl,
> - struct sw_flow_mask *mask)
> -{
> - struct mask_array *ma = ovsl_dereference(tbl->mask_array);
> - int i, ma_count = READ_ONCE(ma->count);
> -
> - /* Remove the deleted mask pointers from the array */
> - for (i = 0; i < ma_count; i++) {
> - if (mask == ovsl_dereference(ma->masks[i]))
> - goto found;
> - }
> -
> - BUG();
> - return;
> -
> -found:
> - WRITE_ONCE(ma->count, ma_count -1);
> -
> - rcu_assign_pointer(ma->masks[i], ma->masks[ma_count -1]);
> - RCU_INIT_POINTER(ma->masks[ma_count -1], NULL);
> -
> - kfree_rcu(mask, rcu);
> -
> - /* Shrink the mask array if necessary. */
> - if (ma->max >= (MASK_ARRAY_SIZE_MIN * 2) &&
> - ma_count <= (ma->max / 3))
> - tbl_mask_array_realloc(tbl, ma->max / 2);
> -}
> -
> -/* Remove 'mask' from the mask list, if it is not needed any more. */
> -static void flow_mask_remove(struct flow_table *tbl, struct sw_flow_mask *mask)
> -{
> - if (mask) {
> - /* ovs-lock is required to protect mask-refcount and
> - * mask list.
> - */
> - ASSERT_OVSL();
> - BUG_ON(!mask->ref_count);
> - mask->ref_count--;
> -
> - if (!mask->ref_count)
> - tbl_mask_array_del_mask(tbl, mask);
> - }
> -}
> -
> /* Must be called with OVS mutex held. */
> void ovs_flow_tbl_remove(struct flow_table *table, struct sw_flow *flow)
> {
> - struct table_instance *ti = ovsl_dereference(table->ti);
> - struct table_instance *ufid_ti = ovsl_dereference(table->ufid_ti);
> -
> - BUG_ON(table->count == 0);
> - hlist_del_rcu(&flow->flow_table.node[ti->node_ver]);
> - table->count--;
> - if (ovs_identifier_is_ufid(&flow->id)) {
> - hlist_del_rcu(&flow->ufid_table.node[ufid_ti->node_ver]);
> - table->ufid_count--;
> - }
> -
> - /* RCU delete the mask. 'flow->mask' is not NULLed, as it should be
> - * accessible as long as the RCU read lock is held.
> - */
> - flow_mask_remove(table, flow->mask);
> + table_instance_remove(table, flow);
Can you just rename table_instance_remove() to ovs_flow_tbl_remove()?
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