Re: Linux 2.4.23-pre4 => NFSD problem on alpha

[Neil Brown]

On Sunday September 14, willy@xxxxxxxxx wrote:
> Hi Marcelo, Neil,
> 
> I've tested -pre4 on my alpha, and noticed that knsfd doesn't work anymore :
> the client sticks in D state forever. It has been working flawlessly for
> weeks with 2.4.22-rc2. What's strange is that 23-pre4 is OK on my athlon with
> the same nfs-utils (1.0.5).
> 
> I have the following NFSD options on both kernels :
> CONFIG_NFSD=m
> CONFIG_NFSD_V3=y
> CONFIG_NFSD_TCP=y
> 
> My alpha kernels were build with GCC 3.2.3, while the athlon one is done with
> 2.95.3.
> 
> If I have some time, I'll try intermediate kernels to find which one brought
> the problem. I noticed that there were knfsd changes in 2.4.23-pre3, perhaps
> they're related. If you want me to try a patch, please ask.

I know what broke it.  Please try this patch and let me know.

NeilBrown

=======================================================================
Fix cmsg setup for sock_sendmsg in svc_sendto

From: Trond Myklebust <trond.myklebust@xxxxxxxxxx>

... see the code in ip_sockglue.c + the macros in socket.h....
AFAICS the control messages have wierd alignment requirements.

 ----------- Diffstat output ------------
 ./net/sunrpc/svcsock.c |   20 ++++++++++----------
 1 files changed, 10 insertions(+), 10 deletions(-)

diff ./net/sunrpc/svcsock.c~current~ ./net/sunrpc/svcsock.c
--- ./net/sunrpc/svcsock.c~current~	2003-09-12 13:41:15.000000000 +1000
+++ ./net/sunrpc/svcsock.c	2003-09-14 21:46:50.000000000 +1000
@@ -317,9 +317,9 @@ svc_sendto(struct svc_rqst *rqstp, struc
 	struct svc_sock	*svsk = rqstp->rq_sock;
 	struct socket	*sock = svsk->sk_sock;
 	struct msghdr	msg;
-	struct { struct cmsghdr cmh;
-		struct in_pktinfo pki;
-	} cm;
+	char 		buffer[CMSG_SPACE(sizeof(struct in_pktinfo))];
+	struct cmsghdr *cmh = (struct cmsghdr *)buffer;
+	struct in_pktinfo *pki = (struct in_pktinfo *)CMSG_DATA(cmh);
 	int		i, buflen, len;
 
 	for (i = buflen = 0; i < nr; i++)
@@ -330,13 +330,13 @@ svc_sendto(struct svc_rqst *rqstp, struc
 	msg.msg_iov     = iov;
 	msg.msg_iovlen  = nr;
 	if (rqstp->rq_prot == IPPROTO_UDP) {
-		msg.msg_control = &cm;
-		msg.msg_controllen = sizeof(cm);
-		cm.cmh.cmsg_len = sizeof(cm);
-		cm.cmh.cmsg_level = SOL_IP;
-		cm.cmh.cmsg_type = IP_PKTINFO;
-		cm.pki.ipi_ifindex = 0;
-		cm.pki.ipi_spec_dst.s_addr = rqstp->rq_daddr;
+		msg.msg_control = cmh;
+		msg.msg_controllen = sizeof(buffer);
+		cmh->cmsg_len = CMSG_LEN(sizeof(*pki));
+		cmh->cmsg_level = SOL_IP;
+		cmh->cmsg_type = IP_PKTINFO;
+		pki->ipi_ifindex = 0;
+		pki->ipi_spec_dst.s_addr = rqstp->rq_daddr;
 	} else {
 		msg.msg_control = NULL;
 		msg.msg_controllen = 0;
-
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