From c18c821fd40ad0ffc199a55be874e556bf999416 Mon Sep 17 00:00:00 2001 From: Boaz Harrosh Date: Tue, 29 Jun 2010 14:33:55 +0300 Subject: [PATCH] nfsd41: Fix a crash when a callback is retried If a callback is retried at nfsd4_cb_recall_done() due to some error, the returned rpc reply crashes here: @@ -514,6 +514,7 @@ decode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *res, u32 dummy; __be32 *p; + BUG_ON(!res); if (res->cbs_minorversion == 0) return 0; [BUG_ON added for demonstration] This is because the nfsd4_cb_done_sequence() has NULLed out the task->tk_msg.rpc_resp pointer. Also eventually the rpc would use the new slot without making sure it is free by calling nfsd41_cb_setup_sequence(). This problem was introduced by a 4.1 protocol addition patch: [0421b5c5] nfsd41: Backchannel: Implement cb_recall over NFSv4.1 Which was overlooking the possibility of an RPC callback retries. For not-4.1 case redoing the _prepare is harmless. Signed-off-by: Boaz Harrosh Signed-off-by: J. Bruce Fields --- fs/nfsd/nfs4callback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c index 1e6497ed3e12..988cbb3a19b6 100644 --- a/fs/nfsd/nfs4callback.c +++ b/fs/nfsd/nfs4callback.c @@ -697,7 +697,7 @@ static void nfsd4_cb_recall_done(struct rpc_task *task, void *calldata) if (dp->dl_retries--) { rpc_delay(task, 2*HZ); task->tk_status = 0; - rpc_restart_call(task); + rpc_restart_call_prepare(task); return; } else { atomic_set(&clp->cl_cb_set, 0); -- 2.20.1