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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Trond Myklebust <trond.myklebust@primarydata.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.15 176/189] SUNRPC: Don't call
 __UDPX_INC_STATS() from a preemptible context
Thread-Topic: [PATCH AUTOSEL for 4.15 176/189] SUNRPC: Don't call
 __UDPX_INC_STATS() from a preemptible context
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Date:   Mon, 9 Apr 2018 00:19:08 +0000
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From: Trond Myklebust <trond.myklebust@primarydata.com>

[ Upstream commit 0afa6b4412988019db14c6bfb8c6cbdf120ca9ad ]

Calling __UDPX_INC_STATS() from a preemptible context leads to a
warning of the form:

 BUG: using __this_cpu_add() in preemptible [00000000] code: kworker/u5:0/3=
1
 caller is xs_udp_data_receive_workfn+0x194/0x270
 CPU: 1 PID: 31 Comm: kworker/u5:0 Not tainted 4.15.0-rc8-00076-g90ea9f1 #2
 Workqueue: xprtiod xs_udp_data_receive_workfn
 Call Trace:
  dump_stack+0x85/0xc1
  check_preemption_disabled+0xce/0xe0
  xs_udp_data_receive_workfn+0x194/0x270
  process_one_work+0x318/0x620
  worker_thread+0x20a/0x390
  ? process_one_work+0x620/0x620
  kthread+0x120/0x130
  ? __kthread_bind_mask+0x60/0x60
  ret_from_fork+0x24/0x30

Since we're taking a spinlock in those functions anyway, let's fix the
issue by moving the call so that it occurs under the spinlock.

Reported-by: kernel test robot <fengguang.wu@intel.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 net/sunrpc/xprtsock.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 6d0cc3b8f932..33e2baebdca7 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1070,18 +1070,18 @@ static void xs_udp_data_read_skb(struct rpc_xprt *x=
prt,
=20
 	/* Suck it into the iovec, verify checksum if not done by hw. */
 	if (csum_partial_copy_to_xdr(&rovr->rq_private_buf, skb)) {
-		__UDPX_INC_STATS(sk, UDP_MIB_INERRORS);
 		spin_lock(&xprt->recv_lock);
+		__UDPX_INC_STATS(sk, UDP_MIB_INERRORS);
 		goto out_unpin;
 	}
=20
-	__UDPX_INC_STATS(sk, UDP_MIB_INDATAGRAMS);
=20
 	spin_lock_bh(&xprt->transport_lock);
 	xprt_adjust_cwnd(xprt, task, copied);
 	spin_unlock_bh(&xprt->transport_lock);
 	spin_lock(&xprt->recv_lock);
 	xprt_complete_rqst(task, copied);
+	__UDPX_INC_STATS(sk, UDP_MIB_INDATAGRAMS);
 out_unpin:
 	xprt_unpin_rqst(rovr);
  out_unlock:
--=20
2.15.1