2020-08-05 07:22:07

by Tonghao Zhang

Subject: [PATCH] net: openvswitch: silence suspicious RCU usage warning

From: Tonghao Zhang <[email protected]>

ovs_flow_tbl_destroy always is called from RCU callback
or error path. It is no need to check if rcu_read_lock
or lockdep_ovsl_is_held was held.

ovs_dp_cmd_fill_info always is called with ovs_mutex,
So use the rcu_dereference_ovsl instead of rcu_dereference
in ovs_flow_tbl_masks_cache_size.

Fixes: 9bf24f594c6a ("net: openvswitch: make masks cache size configurable")
Cc: Eelco Chaudron <[email protected]>
Reported-by: [email protected]
Reported-by: [email protected]
Signed-off-by: Tonghao Zhang <[email protected]>
---
net/openvswitch/flow_table.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
index 6527d84c3ea6..8c12675cbb67 100644
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -518,8 +518,8 @@ 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);
- struct mask_cache *mc = rcu_dereference(table->mask_cache);
- struct mask_array *ma = rcu_dereference_ovsl(table->mask_array);
+ struct mask_cache *mc = rcu_dereference_raw(table->mask_cache);
+ struct mask_array *ma = rcu_dereference_raw(table->mask_array);

call_rcu(&mc->rcu, mask_cache_rcu_cb);
call_rcu(&ma->rcu, mask_array_rcu_cb);
@@ -937,7 +937,7 @@ int ovs_flow_tbl_num_masks(const struct flow_table *table)

u32 ovs_flow_tbl_masks_cache_size(const struct flow_table *table)
{
- struct mask_cache *mc = rcu_dereference(table->mask_cache);
+ struct mask_cache *mc = rcu_dereference_ovsl(table->mask_cache);

return READ_ONCE(mc->cache_size);
}
--
2.26.1

2020-08-05 09:03:22

by Paolo Abeni

Subject: Re: [PATCH] net: openvswitch: silence suspicious RCU usage warning

On Wed, 2020-08-05 at 15:19 +0800, [email protected] wrote:
> From: Tonghao Zhang <[email protected]>
>
> ovs_flow_tbl_destroy always is called from RCU callback
> or error path. It is no need to check if rcu_read_lock
> or lockdep_ovsl_is_held was held.
>
> ovs_dp_cmd_fill_info always is called with ovs_mutex,
> So use the rcu_dereference_ovsl instead of rcu_dereference
> in ovs_flow_tbl_masks_cache_size.
>
> Fixes: 9bf24f594c6a ("net: openvswitch: make masks cache size configurable")
> Cc: Eelco Chaudron <[email protected]>
> Reported-by: [email protected]
> Reported-by: [email protected]
> Signed-off-by: Tonghao Zhang <[email protected]>

Acked-by: Paolo Abeni <[email protected]>

2020-08-05 19:20:33

by David Miller

Subject: Re: [PATCH] net: openvswitch: silence suspicious RCU usage warning

From: [email protected]
Date: Wed, 5 Aug 2020 15:19:11 +0800

> From: Tonghao Zhang <[email protected]>
>
> ovs_flow_tbl_destroy always is called from RCU callback
> or error path. It is no need to check if rcu_read_lock
> or lockdep_ovsl_is_held was held.
>
> ovs_dp_cmd_fill_info always is called with ovs_mutex,
> So use the rcu_dereference_ovsl instead of rcu_dereference
> in ovs_flow_tbl_masks_cache_size.
>
> Fixes: 9bf24f594c6a ("net: openvswitch: make masks cache size configurable")
> Cc: Eelco Chaudron <[email protected]>
> Reported-by: [email protected]
> Reported-by: [email protected]
> Signed-off-by: Tonghao Zhang <[email protected]>

Applied, thank you.

2020-08-05 19:22:37

by Eelco Chaudron

Subject: Re: [PATCH] net: openvswitch: silence suspicious RCU usage warning

On 5 Aug 2020, at 9:19, [email protected] wrote:

> From: Tonghao Zhang <[email protected]>
>
> ovs_flow_tbl_destroy always is called from RCU callback
> or error path. It is no need to check if rcu_read_lock
> or lockdep_ovsl_is_held was held.
>
> ovs_dp_cmd_fill_info always is called with ovs_mutex,
> So use the rcu_dereference_ovsl instead of rcu_dereference
> in ovs_flow_tbl_masks_cache_size.
>
> Fixes: 9bf24f594c6a ("net: openvswitch: make masks cache size
> configurable")
> Cc: Eelco Chaudron <[email protected]>
> Reported-by: [email protected]
> Reported-by: [email protected]
> Signed-off-by: Tonghao Zhang <[email protected]>

Thanks for fixing this, I was (am) on PTO so did not notice it earlier!

Cheers,

Eelco