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[PATCH] sunrpc: fix peername failed on closed listener

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Xiaotian Feng

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Dec 30, 2009, 10:00:02 PM12/30/09
to
There're some warnings of "nfsd: peername failed (err 107)!"
socket error -107 means Transport endpoint is not connected.
This warning message was outputed by svc_tcp_accept() [net/sunrpc/svcsock.c],
when kernel_getpeername returns -107. This means socket might be CLOSED.

And svc_tcp_accept was called by svc_recv() [net/sunrpc/svc_xprt.c]

if (test_bit(XPT_LISTENER, &xprt->xpt_flags)) {
<snip>
newxpt = xprt->xpt_ops->xpo_accept(xprt);
<snip>

So this might happen when xprt->xpt_flags has both XPT_LISTENER and XPT_CLOSE.

Let's take a look at commit b0401d72, this commit has moved the close
processing after do recvfrom method, but this commit also introduces this
warnings, if the xpt_flags has both XPT_LISTENER and XPT_CLOSED, we should
close it, not accpet then close.

Signed-off-by: Xiaotian Feng <df...@redhat.com>
Cc: J. Bruce Fields <bfi...@fieldses.org>
Cc: Neil Brown <ne...@suse.de>
Cc: Trond Myklebust <Trond.M...@netapp.com>
Cc: David S. Miller <da...@davemloft.net>
---
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 1c924ee..187f0f4 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -699,7 +699,8 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
spin_unlock_bh(&pool->sp_lock);

len = 0;
- if (test_bit(XPT_LISTENER, &xprt->xpt_flags)) {
+ if (test_bit(XPT_LISTENER, &xprt->xpt_flags) &&
+ !test_bit(XPT_CLOSE, &xprt->xpt_flags)) {
struct svc_xprt *newxpt;
newxpt = xprt->xpt_ops->xpo_accept(xprt);
if (newxpt) {
--
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Nikola Ciprich

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Jan 4, 2010, 2:20:02 AM1/4/10
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(CCing sta...@kernel.org)
Greg, once this patch is ACKed, can You also queue it for
2.6.32.x please?
thanks!
nik

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J. Bruce Fields

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Jan 5, 2010, 6:10:02 PM1/5/10
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On Thu, Dec 31, 2009 at 10:52:36AM +0800, Xiaotian Feng wrote:
> There're some warnings of "nfsd: peername failed (err 107)!"
> socket error -107 means Transport endpoint is not connected.
> This warning message was outputed by svc_tcp_accept() [net/sunrpc/svcsock.c],
> when kernel_getpeername returns -107. This means socket might be CLOSED.
>
> And svc_tcp_accept was called by svc_recv() [net/sunrpc/svc_xprt.c]
>
> if (test_bit(XPT_LISTENER, &xprt->xpt_flags)) {
> <snip>
> newxpt = xprt->xpt_ops->xpo_accept(xprt);
> <snip>
>
> So this might happen when xprt->xpt_flags has both XPT_LISTENER and XPT_CLOSE.
>
> Let's take a look at commit b0401d72, this commit has moved the close
> processing after do recvfrom method, but this commit also introduces this
> warnings, if the xpt_flags has both XPT_LISTENER and XPT_CLOSED, we should
> close it, not accpet then close.

The logic here seems unnecessarily complicated now, but as a minimal
fix, this seems fine.

Is the *only* justification for this to silence this warning, or is
there some more serious problem I'm missing?

--b.

Xiaotian Feng

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Jan 6, 2010, 4:10:01 AM1/6/10
to
On 01/06/2010 07:01 AM, J. Bruce Fields wrote:
> On Thu, Dec 31, 2009 at 10:52:36AM +0800, Xiaotian Feng wrote:
>> There're some warnings of "nfsd: peername failed (err 107)!"
>> socket error -107 means Transport endpoint is not connected.
>> This warning message was outputed by svc_tcp_accept() [net/sunrpc/svcsock.c],
>> when kernel_getpeername returns -107. This means socket might be CLOSED.
>>
>> And svc_tcp_accept was called by svc_recv() [net/sunrpc/svc_xprt.c]
>>
>> if (test_bit(XPT_LISTENER,&xprt->xpt_flags)) {

>> <snip>
>> newxpt = xprt->xpt_ops->xpo_accept(xprt);
>> <snip>
>>
>> So this might happen when xprt->xpt_flags has both XPT_LISTENER and XPT_CLOSE.
>>
>> Let's take a look at commit b0401d72, this commit has moved the close
>> processing after do recvfrom method, but this commit also introduces this
>> warnings, if the xpt_flags has both XPT_LISTENER and XPT_CLOSED, we should
>> close it, not accpet then close.
>
> The logic here seems unnecessarily complicated now, but as a minimal
> fix, this seems fine.
>
> Is the *only* justification for this to silence this warning, or is
> there some more serious problem I'm missing?

If a xprt->xpt_flags has XPT_CLOSE & XPT_LISTENER, kernel will accept it
first,
and svc_xprt_received(xptr) no mater xpo_accept is suceed or failed,
then svc_delete_xprt(xprt).

I'm not sure what will happened between the svc_xprt_received and
svc_delete_xprt, there isn't any
lock to protect it.

>
> --b.
>
>>
>> Signed-off-by: Xiaotian Feng<df...@redhat.com>
>> Cc: J. Bruce Fields<bfi...@fieldses.org>
>> Cc: Neil Brown<ne...@suse.de>
>> Cc: Trond Myklebust<Trond.M...@netapp.com>
>> Cc: David S. Miller<da...@davemloft.net>
>> ---
>> diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
>> index 1c924ee..187f0f4 100644
>> --- a/net/sunrpc/svc_xprt.c
>> +++ b/net/sunrpc/svc_xprt.c
>> @@ -699,7 +699,8 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
>> spin_unlock_bh(&pool->sp_lock);
>>
>> len = 0;
>> - if (test_bit(XPT_LISTENER,&xprt->xpt_flags)) {
>> + if (test_bit(XPT_LISTENER,&xprt->xpt_flags)&&

>> + !test_bit(XPT_CLOSE,&xprt->xpt_flags)) {

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