diff mbox series

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

Message ID 160398318667.8898.856205445259063348.stgit@ebuild (mailing list archive)
State Not Applicable
Delegated to: Netdev Maintainers
Headers show
Series [net] net: openvswitch: silence suspicious RCU usage warning | expand

Commit Message

Eelco Chaudron Oct. 29, 2020, 2:53 p.m. UTC
Silence suspicious RCU usage warning in ovs_flow_tbl_masks_cache_resize()
by replacing rcu_dereference() with rcu_dereference_ovsl().

In addition, when creating a new datapath, make sure it's configured under
the ovs_lock.

Fixes: 9bf24f594c6a ("net: openvswitch: make masks cache size configurable")
Reported-by: syzbot+9a8f8bfcc56e8578016c@syzkaller.appspotmail.com
Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
---
 net/openvswitch/datapath.c   |    8 ++++----
 net/openvswitch/flow_table.c |    2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

Comments

Jakub Kicinski Oct. 30, 2020, 9:28 p.m. UTC | #1
On Thu, 29 Oct 2020 15:53:21 +0100 Eelco Chaudron wrote:
> Silence suspicious RCU usage warning in ovs_flow_tbl_masks_cache_resize()
> by replacing rcu_dereference() with rcu_dereference_ovsl().
> 
> In addition, when creating a new datapath, make sure it's configured under
> the ovs_lock.
> 
> Fixes: 9bf24f594c6a ("net: openvswitch: make masks cache size configurable")
> Reported-by: syzbot+9a8f8bfcc56e8578016c@syzkaller.appspotmail.com
> Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
> ---
>  net/openvswitch/datapath.c   |    8 ++++----
>  net/openvswitch/flow_table.c |    2 +-
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
> index 832f898edb6a..020f8539fede 100644
> --- a/net/openvswitch/datapath.c
> +++ b/net/openvswitch/datapath.c
> @@ -1695,6 +1695,9 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
>  	if (err)
>  		goto err_destroy_ports;
>  
> +	/* So far only local changes have been made, now need the lock. */
> +	ovs_lock();

Should we move the lock below assignments to param?

Looks a little strange to protect stack variables with a global lock.

>  	/* Set up our datapath device. */
>  	parms.name = nla_data(a[OVS_DP_ATTR_NAME]);
>  	parms.type = OVS_VPORT_TYPE_INTERNAL;
> @@ -1707,9 +1710,6 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
>  	if (err)
>  		goto err_destroy_meters;
>  
> -	/* So far only local changes have been made, now need the lock. */
> -	ovs_lock();
> -
>  	vport = new_vport(&parms);
>  	if (IS_ERR(vport)) {
>  		err = PTR_ERR(vport);
> @@ -1725,7 +1725,6 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
>  				ovs_dp_reset_user_features(skb, info);
>  		}
>  
> -		ovs_unlock();
>  		goto err_destroy_meters;
>  	}
>  
> @@ -1742,6 +1741,7 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
>  	return 0;
>  
>  err_destroy_meters:

Let's update the name of the label.

> +	ovs_unlock();
>  	ovs_meters_exit(dp);
>  err_destroy_ports:
>  	kfree(dp->ports);
> diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
> index f3486a37361a..c89c8da99f1a 100644
> --- a/net/openvswitch/flow_table.c
> +++ b/net/openvswitch/flow_table.c
> @@ -390,7 +390,7 @@ static struct mask_cache *tbl_mask_cache_alloc(u32 size)
>  }
>  int ovs_flow_tbl_masks_cache_resize(struct flow_table *table, u32 size)
>  {
> -	struct mask_cache *mc = rcu_dereference(table->mask_cache);
> +	struct mask_cache *mc = rcu_dereference_ovsl(table->mask_cache);
>  	struct mask_cache *new;
>  
>  	if (size == mc->cache_size)
>
Eelco Chaudron Nov. 2, 2020, 8:52 a.m. UTC | #2
On 30 Oct 2020, at 22:28, Jakub Kicinski wrote:

> On Thu, 29 Oct 2020 15:53:21 +0100 Eelco Chaudron wrote:
>> Silence suspicious RCU usage warning in 
>> ovs_flow_tbl_masks_cache_resize()
>> by replacing rcu_dereference() with rcu_dereference_ovsl().
>>
>> In addition, when creating a new datapath, make sure it's configured 
>> under
>> the ovs_lock.
>>
>> Fixes: 9bf24f594c6a ("net: openvswitch: make masks cache size 
>> configurable")
>> Reported-by: syzbot+9a8f8bfcc56e8578016c@syzkaller.appspotmail.com
>> Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
>> ---
>>  net/openvswitch/datapath.c   |    8 ++++----
>>  net/openvswitch/flow_table.c |    2 +-
>>  2 files changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
>> index 832f898edb6a..020f8539fede 100644
>> --- a/net/openvswitch/datapath.c
>> +++ b/net/openvswitch/datapath.c
>> @@ -1695,6 +1695,9 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, 
>> struct genl_info *info)
>>  	if (err)
>>  		goto err_destroy_ports;
>>
>> +	/* So far only local changes have been made, now need the lock. */
>> +	ovs_lock();
>
> Should we move the lock below assignments to param?
>
> Looks a little strange to protect stack variables with a global lock.

You are right, I should have moved it down after the assignment. I will 
send out a v2.

>>  	/* Set up our datapath device. */
>>  	parms.name = nla_data(a[OVS_DP_ATTR_NAME]);
>>  	parms.type = OVS_VPORT_TYPE_INTERNAL;
>> @@ -1707,9 +1710,6 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, 
>> struct genl_info *info)
>>  	if (err)
>>  		goto err_destroy_meters;
>>
>> -	/* So far only local changes have been made, now need the lock. */
>> -	ovs_lock();
>> -
>>  	vport = new_vport(&parms);
>>  	if (IS_ERR(vport)) {
>>  		err = PTR_ERR(vport);
>> @@ -1725,7 +1725,6 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, 
>> struct genl_info *info)
>>  				ovs_dp_reset_user_features(skb, info);
>>  		}
>>
>> -		ovs_unlock();
>>  		goto err_destroy_meters;
>>  	}
>>
>> @@ -1742,6 +1741,7 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, 
>> struct genl_info *info)
>>  	return 0;
>>
>>  err_destroy_meters:
>
> Let's update the name of the label.

Guess now it is, unlock and destroy meters, so what label are you 
looking for?

err_unlock_and_destroy_meters: which looks a bit long, or just 
err_unlock:

>> +	ovs_unlock();
>>  	ovs_meters_exit(dp);
>>  err_destroy_ports:
>>  	kfree(dp->ports);
>> diff --git a/net/openvswitch/flow_table.c 
>> b/net/openvswitch/flow_table.c
>> index f3486a37361a..c89c8da99f1a 100644
>> --- a/net/openvswitch/flow_table.c
>> +++ b/net/openvswitch/flow_table.c
>> @@ -390,7 +390,7 @@ static struct mask_cache 
>> *tbl_mask_cache_alloc(u32 size)
>>  }
>>  int ovs_flow_tbl_masks_cache_resize(struct flow_table *table, u32 
>> size)
>>  {
>> -	struct mask_cache *mc = rcu_dereference(table->mask_cache);
>> +	struct mask_cache *mc = rcu_dereference_ovsl(table->mask_cache);
>>  	struct mask_cache *new;
>>
>>  	if (size == mc->cache_size)
>>
Jakub Kicinski Nov. 2, 2020, 7:51 p.m. UTC | #3
On Mon, 02 Nov 2020 09:52:19 +0100 Eelco Chaudron wrote:
> On 30 Oct 2020, at 22:28, Jakub Kicinski wrote:
> >> @@ -1695,6 +1695,9 @@ static int ovs_dp_cmd_new(struct sk_buff *skb, 
> >> struct genl_info *info)
> >>  	if (err)
> >>  		goto err_destroy_ports;
> >>
> >> +	/* So far only local changes have been made, now need the lock. */
> >> +	ovs_lock();  
> >
> > Should we move the lock below assignments to param?
> >
> > Looks a little strange to protect stack variables with a global lock.  
> 
> You are right, I should have moved it down after the assignment. I will 
> send out a v2.
> 
> > Let's update the name of the label.  
> 
> Guess now it is, unlock and destroy meters, so what label are you 
> looking for?
> 
> err_unlock_and_destroy_meters: which looks a bit long, or just 
> err_unlock:

I feel like I saw some names like err_unlock_and_destroy_meters in OvS
code, but can't find them in this file right now.

I'd personally go for kist err_unlock, or maybe err_unlock_ovs as is
used in other functions in this file.

But as long as it starts with err_unlock it's fine by me :)
Eelco Chaudron Nov. 3, 2020, 8:26 a.m. UTC | #4
On 2 Nov 2020, at 20:51, Jakub Kicinski wrote:

> On Mon, 02 Nov 2020 09:52:19 +0100 Eelco Chaudron wrote:
>> On 30 Oct 2020, at 22:28, Jakub Kicinski wrote:
>>>> @@ -1695,6 +1695,9 @@ static int ovs_dp_cmd_new(struct sk_buff *skb,
>>>> struct genl_info *info)
>>>>  	if (err)
>>>>  		goto err_destroy_ports;
>>>>
>>>> +	/* So far only local changes have been made, now need the lock. */
>>>> +	ovs_lock();
>>>
>>> Should we move the lock below assignments to param?
>>>
>>> Looks a little strange to protect stack variables with a global lock.
>>
>> You are right, I should have moved it down after the assignment. I will
>> send out a v2.
>>
>>> Let's update the name of the label.
>>
>> Guess now it is, unlock and destroy meters, so what label are you
>> looking for?
>>
>> err_unlock_and_destroy_meters: which looks a bit long, or just
>> err_unlock:
>
> I feel like I saw some names like err_unlock_and_destroy_meters in OvS
> code, but can't find them in this file right now.
>
> I'd personally go for kist err_unlock, or maybe err_unlock_ovs as is
> used in other functions in this file.
>
> But as long as it starts with err_unlock it's fine by me :)

Ack, sent out a v2.
diff mbox series

Patch

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 832f898edb6a..020f8539fede 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1695,6 +1695,9 @@  static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	if (err)
 		goto err_destroy_ports;
 
+	/* So far only local changes have been made, now need the lock. */
+	ovs_lock();
+
 	/* Set up our datapath device. */
 	parms.name = nla_data(a[OVS_DP_ATTR_NAME]);
 	parms.type = OVS_VPORT_TYPE_INTERNAL;
@@ -1707,9 +1710,6 @@  static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	if (err)
 		goto err_destroy_meters;
 
-	/* So far only local changes have been made, now need the lock. */
-	ovs_lock();
-
 	vport = new_vport(&parms);
 	if (IS_ERR(vport)) {
 		err = PTR_ERR(vport);
@@ -1725,7 +1725,6 @@  static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 				ovs_dp_reset_user_features(skb, info);
 		}
 
-		ovs_unlock();
 		goto err_destroy_meters;
 	}
 
@@ -1742,6 +1741,7 @@  static int ovs_dp_cmd_new(struct sk_buff *skb, struct genl_info *info)
 	return 0;
 
 err_destroy_meters:
+	ovs_unlock();
 	ovs_meters_exit(dp);
 err_destroy_ports:
 	kfree(dp->ports);
diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
index f3486a37361a..c89c8da99f1a 100644
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -390,7 +390,7 @@  static struct mask_cache *tbl_mask_cache_alloc(u32 size)
 }
 int ovs_flow_tbl_masks_cache_resize(struct flow_table *table, u32 size)
 {
-	struct mask_cache *mc = rcu_dereference(table->mask_cache);
+	struct mask_cache *mc = rcu_dereference_ovsl(table->mask_cache);
 	struct mask_cache *new;
 
 	if (size == mc->cache_size)