sunrpc: Fix misplaced barrier in call_decode
[ Upstream commit f8f7e0fb22b2e75be55f2f0c13e229e75b0eac07 ]
Fix a misplaced barrier in call_decode. The struct rpc_rqst is modified
as follows by xprt_complete_rqst:
req->rq_private_buf.len = copied;
/* Ensure all writes are done before we update */
/* req->rq_reply_bytes_recvd */
smp_wmb();
req->rq_reply_bytes_recvd = copied;
And currently read as follows by call_decode:
smp_rmb(); // misplaced
if (!req->rq_reply_bytes_recvd)
goto out;
req->rq_rcv_buf.len = req->rq_private_buf.len;
This patch places the smp_rmb after the if to ensure that
rq_reply_bytes_recvd and rq_private_buf.len are read in order.
Fixes: 9ba828861c
("SUNRPC: Don't try to parse incomplete RPC messages")
Signed-off-by: Baptiste Lepers <baptiste.lepers@gmail.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -2505,12 +2505,6 @@ call_decode(struct rpc_task *task)
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task->tk_flags &= ~RPC_CALL_MAJORSEEN;
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}
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/*
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* Ensure that we see all writes made by xprt_complete_rqst()
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* before it changed req->rq_reply_bytes_recvd.
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*/
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smp_rmb();
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/*
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* Did we ever call xprt_complete_rqst()? If not, we should assume
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* the message is incomplete.
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@ -2519,6 +2513,11 @@ call_decode(struct rpc_task *task)
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if (!req->rq_reply_bytes_recvd)
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goto out;
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/* Ensure that we see all writes made by xprt_complete_rqst()
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* before it changed req->rq_reply_bytes_recvd.
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*/
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smp_rmb();
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req->rq_rcv_buf.len = req->rq_private_buf.len;
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/* Check that the softirq receive buffer is valid */
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