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SUNRPC: Use RCU to dereference the rpc_clnt.cl_xprt field

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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>
This commit is contained in:
Trond Myklebust
2012-03-01 17:00:56 -05:00
parent a3ca5651cb
commit 2446ab6070
13 changed files with 175 additions and 50 deletions
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25
fs/nfs/nfs4state.c
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@@ -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);
}
}
/*