SUNRPC: Fix potential races in xprt_lock_write_next()
We have to ensure that the wake up from the waitqueue and the assignment
of xprt->snd_task are atomic. We can do this by assigning the snd_task
while under the waitqueue spinlock.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index a42e60d..f0e9881 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -190,23 +190,22 @@
static void nfs4_end_drain_session(struct nfs_client *clp)
{
struct nfs4_session *ses = clp->cl_session;
+ struct nfs4_slot_table *tbl;
int max_slots;
if (ses == NULL)
return;
+ tbl = &ses->fc_slot_table;
if (test_and_clear_bit(NFS4_SESSION_DRAINING, &ses->session_state)) {
- spin_lock(&ses->fc_slot_table.slot_tbl_lock);
- max_slots = ses->fc_slot_table.max_slots;
+ spin_lock(&tbl->slot_tbl_lock);
+ max_slots = tbl->max_slots;
while (max_slots--) {
- struct rpc_task *task;
-
- task = rpc_wake_up_next(&ses->fc_slot_table.
- slot_tbl_waitq);
- if (!task)
+ if (rpc_wake_up_first(&tbl->slot_tbl_waitq,
+ nfs4_set_task_privileged,
+ NULL) == NULL)
break;
- rpc_task_set_priority(task, RPC_PRIORITY_PRIVILEGED);
}
- spin_unlock(&ses->fc_slot_table.slot_tbl_lock);
+ spin_unlock(&tbl->slot_tbl_lock);
}
}