[3.13.y-ckt stable] Patch "SUNRPC: Fix locking around callback channel reply receive" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Mon Dec 8 20:10:21 UTC 2014


This is a note to let you know that I have just added a patch titled

    SUNRPC: Fix locking around callback channel reply receive

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt13.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From b057063947cb4b63f0b9ebdc3b544bb68eba399d Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust at primarydata.com>
Date: Wed, 12 Nov 2014 18:04:04 -0500
Subject: SUNRPC: Fix locking around callback channel reply receive

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 at primarydata.com>
Reviewed-by: Jeff Layton <jlayton at primarydata.com>
Signed-off-by: J. Bruce Fields <bfields at redhat.com>
[ kamal: backport to 3.13-stable: context ]
Signed-off-by: Kamal Mostafa <kamal at canonical.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 d06cb87..d4d2a2d 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -989,17 +989,12 @@ 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));
 	/*
@@ -1010,11 +1005,21 @@ 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, rqstp->rq_arg.len);
 	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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