Messages in this thread |  | | | From | "Suzanne Wood" <> | | Subject | rcu read-side protection | | Date | Tue, 16 Aug 2005 17:09:29 -0700 |
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In dn_neigh_construct() of linux-2.6.12/net/decnet/dn_neigh.c
static int dn_neigh_construct(struct neighbour *neigh) { struct net_device *dev = neigh->dev; struct dn_neigh *dn = (struct dn_neigh *)neigh; struct dn_dev *dn_db; struct neigh_parms *parms; rcu_read_lock(); dn_db = rcu_dereference(dev->dn_ptr); if (dn_db == NULL) { rcu_read_unlock(); return -EINVAL; } parms = dn_db->neigh_parms; if (!parms) { rcu_read_unlock(); return -EINVAL; } __neigh_parms_put(neigh->parms); neigh->parms = neigh_parms_clone(parms); rcu_read_unlock();
if (dn_db->use_long) neigh->ops = &dn_long_ops; else neigh->ops = &dn_short_ops; if (dn->flags & DN_NDFLAG_P3) neigh->ops = &dn_phase3_ops; neigh->nud_state = NUD_NOARP; neigh->output = neigh->ops->connected_output;
if ((dev->type == ARPHRD_IPGRE) || (dev->flags & IFF_POINTOPOINT)) memcpy(neigh->ha, dev->broadcast, dev->addr_len); else if ((dev->type == ARPHRD_ETHER) || (dev->type == ARPHRD_LOOPBACK)) dn_dn2eth(neigh->ha, dn->addr); else { if (net_ratelimit()) printk(KERN_DEBUG "Trying to create neigh for hw %d\n", dev->type); return -EINVAL; } A read-side critical section is marked to protect the dereference of the dn_ptr and assignment to dn_db which is a pointer to a dn_dev. (struct net_device is defined in /linux/netdevice.h and its dn_ptr in /include/net/dn_dev.h) Should this rcu-protection be extended to the line following rcu_read_lock()? Even though use_long is a simple char, it appears to be a member of an rcu-protected structure.
Thank you.
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