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SUNRPC: add WARN_ON_ONCE for potential deadlock

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rpc_shutdown_client should never be called from a workqueue context.
If it is, it could deadlock looping forever trying to kill tasks that are
assigned to the same kworker thread (and will never run rpc_exit_task).

Signed-off-by: Weston Andros Adamson <dros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Weston Andros Adamson 2012-10-30 17:01:40 -04:00 • committed by Trond Myklebust
commit 168e4b39d1
1 changed files with 7 additions and 0 deletions
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7
net/sunrpc/clnt.c
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@ -607,6 +607,13 @@ EXPORT_SYMBOL_GPL(rpc_killall_tasks);
*/
void rpc_shutdown_client(struct rpc_clnt *clnt)
{
/*
* To avoid deadlock, never call rpc_shutdown_client from a
* workqueue context!
*/
WARN_ON_ONCE(current->flags & PF_WQ_WORKER);
might_sleep();
dprintk_rcu("RPC: shutting down %s client for %s\n",
clnt->cl_protname,
rcu_dereference(clnt->cl_xprt)->servername);