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authorTrond Myklebust <Trond.Myklebust@netapp.com>2012-03-01 17:00:56 -0500
committerTrond Myklebust <Trond.Myklebust@netapp.com>2012-03-02 15:36:38 -0500
commit2446ab6070861aba2dd9229463ffbc40016a9f33 (patch)
tree2e366c3236788936b9f4f58c0787ae01c265f4a4 /fs/nfs/nfs4state.c
parenta3ca5651cb5eebe2e56e510bbf5cd60abc301c9f (diff)
SUNRPC: Use RCU to dereference the rpc_clnt.cl_xprt field
A migration event will replace the rpc_xprt used by an rpc_clnt. To ensure this can be done safely, all references to cl_xprt must now use a form of rcu_dereference(). Special care is taken with rpc_peeraddr2str(), which returns a pointer to memory whose lifetime is the same as the rpc_xprt. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> [ cel: fix lockdep splats and layering violations ] [ cel: forward ported to 3.4 ] [ cel: remove rpc_max_reqs(), add rpc_net_ns() ] Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs/nfs4state.c')
-rw-r--r--fs/nfs/nfs4state.c25
1 files changed, 17 insertions, 8 deletions
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index c1111a37dc14..bae959e294cd 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1037,19 +1037,28 @@ static void nfs4_clear_state_manager_bit(struct nfs_client *clp)
void nfs4_schedule_state_manager(struct nfs_client *clp)
{
struct task_struct *task;
+ char buf[INET6_ADDRSTRLEN + sizeof("-manager") + 1];
if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
return;
__module_get(THIS_MODULE);
atomic_inc(&clp->cl_count);
- task = kthread_run(nfs4_run_state_manager, clp, "%s-manager",
- rpc_peeraddr2str(clp->cl_rpcclient,
- RPC_DISPLAY_ADDR));
- if (!IS_ERR(task))
- return;
- nfs4_clear_state_manager_bit(clp);
- nfs_put_client(clp);
- module_put(THIS_MODULE);
+
+ /* The rcu_read_lock() is not strictly necessary, as the state
+ * manager is the only thread that ever changes the rpc_xprt
+ * after it's initialized. At this point, we're single threaded. */
+ rcu_read_lock();
+ snprintf(buf, sizeof(buf), "%s-manager",
+ rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));
+ rcu_read_unlock();
+ task = kthread_run(nfs4_run_state_manager, clp, buf);
+ if (IS_ERR(task)) {
+ printk(KERN_ERR "%s: kthread_run: %ld\n",
+ __func__, PTR_ERR(task));
+ nfs4_clear_state_manager_bit(clp);
+ nfs_put_client(clp);
+ module_put(THIS_MODULE);
+ }
}
/*