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Subject[PATCH 3.4 008/176] SUNRPC: Fix locking around callback channel reply receive
Date
From: Trond Myklebust <trond.myklebust@primarydata.com>

3.4.107-rc1 review patch. If anyone has any objections, please let me know.

------------------


commit 093a1468b6edb0e568be7311b8d2228d205702db upstream.

Both xprt_lookup_rqst() and xprt_complete_rqst() require that you
take the transport lock in order to avoid races with xprt_transmit().

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Reviewed-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
net/sunrpc/svcsock.c | 27 ++++++++++++++++-----------
1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 4c23cfc..a0769e1 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1055,17 +1055,12 @@ static int receive_cb_reply(struct svc_sock *svsk, struct svc_rqst *rqstp)
xid = *p++;
calldir = *p;

- if (bc_xprt)
- req = xprt_lookup_rqst(bc_xprt, xid);
-
- if (!req) {
- printk(KERN_NOTICE
- "%s: Got unrecognized reply: "
- "calldir 0x%x xpt_bc_xprt %p xid %08x\n",
- __func__, ntohl(calldir),
- bc_xprt, xid);
+ if (!bc_xprt)
return -EAGAIN;
- }
+ spin_lock_bh(&bc_xprt->transport_lock);
+ req = xprt_lookup_rqst(bc_xprt, xid);
+ if (!req)
+ goto unlock_notfound;

memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
/*
@@ -1076,11 +1071,21 @@ static int receive_cb_reply(struct svc_sock *svsk, struct svc_rqst *rqstp)
dst = &req->rq_private_buf.head[0];
src = &rqstp->rq_arg.head[0];
if (dst->iov_len < src->iov_len)
- return -EAGAIN; /* whatever; just giving up. */
+ goto unlock_eagain; /* whatever; just giving up. */
memcpy(dst->iov_base, src->iov_base, src->iov_len);
xprt_complete_rqst(req->rq_task, svsk->sk_reclen);
rqstp->rq_arg.len = 0;
+ spin_unlock_bh(&bc_xprt->transport_lock);
return 0;
+unlock_notfound:
+ printk(KERN_NOTICE
+ "%s: Got unrecognized reply: "
+ "calldir 0x%x xpt_bc_xprt %p xid %08x\n",
+ __func__, ntohl(calldir),
+ bc_xprt, ntohl(xid));
+unlock_eagain:
+ spin_unlock_bh(&bc_xprt->transport_lock);
+ return -EAGAIN;
}

static int copy_pages_to_kvecs(struct kvec *vec, struct page **pages, int len)
--
1.9.1


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