On Fri, 2014-05-30 at 11:00 -0400, Neil Horman wrote: > The Cnic driver handles lots of ulp operations in its netdevice event hanlder. > To do this, it accesses the ulp_ops array, which is an rcu protected array. > However, some ulp operations (like bnx2fc_indicate_netevent) try to lock > mutexes, which might sleep (somthing that you can't do while holding rcu read > side locks if you've configured non-preemptive rcu. > > Fix this by changing the dereference method. All accesses to the ulp_ops > array > for a cnic dev are modified under the protection of the rtnl lock, and so we > can > safely just use rcu_dereference_rtnl, and remove the rcu_read_lock here
Because the bnx2fc function can sleep, we need a more complete fix to prevent the ulp_ops from going away when the device is unregistered. synchronize_rcu() won't be able to protect it. I'll post the patch later today. Thanks. > > Signed-off-by: Neil Horman <[email protected]> > CC: "David S. Miller" <[email protected]> > CC: Michael Chan <[email protected]> > CC: [email protected] > CC: Robert Love <[email protected]> > CC: Vasu Dev <[email protected]> > --- > drivers/net/ethernet/broadcom/cnic.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/drivers/net/ethernet/broadcom/cnic.c > b/drivers/net/ethernet/broadcom/cnic.c > index f58a8b8..bfdb9f0 100644 > --- a/drivers/net/ethernet/broadcom/cnic.c > +++ b/drivers/net/ethernet/broadcom/cnic.c > @@ -5622,12 +5622,11 @@ static void cnic_rcv_netevent(struct cnic_local *cp, > unsigned long event, > { > int if_type; > > - rcu_read_lock(); > for (if_type = 0; if_type < MAX_CNIC_ULP_TYPE; if_type++) { > struct cnic_ulp_ops *ulp_ops; > void *ctx; > > - ulp_ops = rcu_dereference(cp->ulp_ops[if_type]); > + ulp_ops = rcu_dereference_rtnl(cp->ulp_ops[if_type]); > if (!ulp_ops || !ulp_ops->indicate_netevent) > continue; > > @@ -5635,7 +5634,6 @@ static void cnic_rcv_netevent(struct cnic_local *cp, > unsigned long event, > > ulp_ops->indicate_netevent(ctx, event, vlan_id); > } > - rcu_read_unlock(); > } > > /* netdev event handler */ _______________________________________________ fcoe-devel mailing list [email protected] http://lists.open-fcoe.org/mailman/listinfo/fcoe-devel
