Re: [PATCH net 1/3] bonding: Fix race condition between bond_enslave() and bond_3ad_update_lacp_rate()

[Jay Vosburgh <fubar@us.ibm.com>]

Nikolay Aleksandrov <nikolay@redhat.com> wrote:

>port->slave can be NULL since it's being initialized in bond_enslave
>thus dereferencing a NULL pointer in bond_3ad_update_lacp_rate()
>Also fix a minor bug, which could cause a port not to have
>AD_STATE_LACP_TIMEOUT since there's no sync between
>bond_3ad_update_lacp_rate() and bond_3ad_bind_slave(), by changing
>the read_lock to a write_lock_bh in bond_3ad_update_lacp_rate().

Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>

>Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
>---
> drivers/net/bonding/bond_3ad.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
>index a030e63..1720742 100644
>--- a/drivers/net/bonding/bond_3ad.c
>+++ b/drivers/net/bonding/bond_3ad.c
>@@ -2494,11 +2494,13 @@ void bond_3ad_update_lacp_rate(struct bonding *bond)
> 	struct port *port = NULL;
> 	int lacp_fast;
>
>-	read_lock(&bond->lock);
>+	write_lock_bh(&bond->lock);
> 	lacp_fast = bond->params.lacp_fast;
>
> 	bond_for_each_slave(bond, slave, i) {
> 		port = &(SLAVE_AD_INFO(slave).port);
>+		if (port->slave == NULL)
>+			continue;
> 		__get_state_machine_lock(port);
> 		if (lacp_fast)
> 			port->actor_oper_port_state |= AD_STATE_LACP_TIMEOUT;
>@@ -2507,5 +2509,5 @@ void bond_3ad_update_lacp_rate(struct bonding *bond)
> 		__release_state_machine_lock(port);
> 	}
>
>-	read_unlock(&bond->lock);
>+	write_unlock_bh(&bond->lock);
> }
>-- 
>1.7.11.7
>