| Message ID | 20200117214720.1960-1-shiraz.saleem@intel.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [rdma-nxt] i40iw: Do an RCU lookup in i40iw_add_ipv4_addr | expand |
On Fri, Jan 17, 2020 at 03:47:20PM -0600, Shiraz Saleem wrote: > From: "Shiraz Saleem" <shiraz.saleem@intel.com> > > The in_dev_for_each_ifa_rtnl iterator in i40iw_add_ipv4_addr > requires that the rtnl lock be held. But the rtnl_trylock/unlock > scheme in this function does not guarantee it. > > Replace the rtnl locking with an RCU lookup since there are > no netdev object updates in this function. > > Fixes: 8e06af711bf2 ("i40iw: add main, hdr, status") > Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com> > --- > drivers/infiniband/hw/i40iw/i40iw_main.c | 16 +++++----------- > 1 file changed, 5 insertions(+), 11 deletions(-) > > diff --git a/drivers/infiniband/hw/i40iw/i40iw_main.c b/drivers/infiniband/hw/i40iw/i40iw_main.c > index 2386143..d7a1219 100644 > --- a/drivers/infiniband/hw/i40iw/i40iw_main.c > +++ b/drivers/infiniband/hw/i40iw/i40iw_main.c > @@ -1212,22 +1212,19 @@ static void i40iw_add_ipv4_addr(struct i40iw_device *iwdev) > { > struct net_device *dev; > struct in_device *idev; > - bool got_lock = true; > u32 ip_addr; > > - if (!rtnl_trylock()) > - got_lock = false; > - > - for_each_netdev(&init_net, dev) { > + rcu_read_lock(); > + for_each_netdev_rcu(&init_net, dev) { > if ((((rdma_vlan_dev_vlan_id(dev) < 0xFFFF) && > (rdma_vlan_dev_real_dev(dev) == iwdev->netdev)) || > (dev == iwdev->netdev)) && (dev->flags & IFF_UP)) { > const struct in_ifaddr *ifa; The rtnl does not just protect the pointers, but also values like flags from changing. When using RCU any varient values of the dev should be read with READ_ONCE, such as flags. I'm not completely sure the vlan tests are OK under RCU either, but netdev has historically been loose on its READ_ONCE/WRITE_ONCE annotations.. Jason
diff --git a/drivers/infiniband/hw/i40iw/i40iw_main.c b/drivers/infiniband/hw/i40iw/i40iw_main.c index 2386143..d7a1219 100644 --- a/drivers/infiniband/hw/i40iw/i40iw_main.c +++ b/drivers/infiniband/hw/i40iw/i40iw_main.c @@ -1212,22 +1212,19 @@ static void i40iw_add_ipv4_addr(struct i40iw_device *iwdev) { struct net_device *dev; struct in_device *idev; - bool got_lock = true; u32 ip_addr; - if (!rtnl_trylock()) - got_lock = false; - - for_each_netdev(&init_net, dev) { + rcu_read_lock(); + for_each_netdev_rcu(&init_net, dev) { if ((((rdma_vlan_dev_vlan_id(dev) < 0xFFFF) && (rdma_vlan_dev_real_dev(dev) == iwdev->netdev)) || (dev == iwdev->netdev)) && (dev->flags & IFF_UP)) { const struct in_ifaddr *ifa; - idev = in_dev_get(dev); + idev = __in_dev_get_rcu(dev); if (!idev) continue; - in_dev_for_each_ifa_rtnl(ifa, idev) { + in_dev_for_each_ifa_rcu(ifa, idev) { i40iw_debug(&iwdev->sc_dev, I40IW_DEBUG_CM, "IP=%pI4, vlan_id=%d, MAC=%pM\n", &ifa->ifa_address, rdma_vlan_dev_vlan_id(dev), dev->dev_addr); @@ -1239,12 +1236,9 @@ static void i40iw_add_ipv4_addr(struct i40iw_device *iwdev) true, I40IW_ARP_ADD); } - - in_dev_put(idev); } } - if (got_lock) - rtnl_unlock(); + rcu_read_unlock(); } /**