[PATCH] Stop recvfrom errors from killing nfsd

[PATCH] Stop recvfrom errors from killing nfsd

[Olaf Kirch]

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Hi,

I just looked into a customer report about nfsd processes terminating
because svc_recv() returned -107.

This is caused by svc_tcp_recvfrom propagating errors such as ENOTCONN
and ECONNRESET up to svc_recv, which is not equipped to deal with this.
svc_recv expects the return value from svsk->sk_recvfrom to be either
positive (a packet length), 0 (accept call or incomplete record), or
-EAGAIN (no data). Any other error codes are treated just like a packet
length.

The original code in svc_tcp_recvfrom would always kill the socket
when it got an unexpected error, and return EAGAIN. This was changed
some time between 2.4.18 and 2.4.21 - I don't know for what reasons.

The patch below reverts that change.

Alternatively, we could add special case treatment for certain error codes;
e.g. propagating EINTR up to nfsd while making ECONNRESET and ENOTCONN
simply kill the connection.

Cheers,
Olaf
-- 
Olaf Kirch     |  The Hardware Gods hate me.
okir@suse.de   |
---------------+ 

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From: Olaf Kirch <okir@suse.de>

svc_recv is not equipped to deal with error codes other than EAGAIN,
and will propagate anything else (such as ECONNRESET) up to nfsd,
causing it to exit.

Signed-off-by: Olaf Kirch <okir@suse.de>

Index: 2.4.21/net/sunrpc/svcsock.c
===================================================================
--- 2.4.21.orig/net/sunrpc/svcsock.c	2003-06-13 16:51:39.000000000 +0200
+++ 2.4.21/net/sunrpc/svcsock.c	2004-09-20 13:11:53.000000000 +0200
@@ -894,7 +894,7 @@ svc_tcp_recvfrom(struct svc_rqst *rqstp)
 	} else {
 		printk(KERN_NOTICE "%s: recvfrom returned errno %d\n",
 					svsk->sk_server->sv_name, -len);
-		svc_sock_received(svsk);
+		goto err_delete;
 	}
 
 	return len;

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