2009-12-31 02:54:57

by Xiaotian Feng

[permalink] [raw]
Subject: [PATCH] sunrpc: fix peername failed on closed listener

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 <[email protected]>
Cc: J. Bruce Fields <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: David S. Miller <[email protected]>
---
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) {


2010-01-04 07:12:32

by Nikola Ciprich

[permalink] [raw]
Subject: Re: [PATCH] sunrpc: fix peername failed on closed listener

(CCing [email protected])
Greg, once this patch is ACKed, can You also queue it for
2.6.32.x please?
thanks!
nik

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.
>
> Signed-off-by: Xiaotian Feng <[email protected]>
> Cc: J. Bruce Fields <[email protected]>
> Cc: Neil Brown <[email protected]>
> Cc: Trond Myklebust <[email protected]>
> Cc: David S. Miller <[email protected]>
> ---
> 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) {
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>

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

2010-01-05 23:00:48

by J. Bruce Fields

[permalink] [raw]
Subject: Re: [PATCH] sunrpc: fix peername failed on closed listener

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.

>
> Signed-off-by: Xiaotian Feng <[email protected]>
> Cc: J. Bruce Fields <[email protected]>
> Cc: Neil Brown <[email protected]>
> Cc: Trond Myklebust <[email protected]>
> Cc: David S. Miller <[email protected]>
> ---
> 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) {

2010-01-06 09:07:43

by Xiaotian Feng

[permalink] [raw]
Subject: Re: [PATCH] sunrpc: fix peername failed on closed listener

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<[email protected]>
>> Cc: J. Bruce Fields<[email protected]>
>> Cc: Neil Brown<[email protected]>
>> Cc: Trond Myklebust<[email protected]>
>> Cc: David S. Miller<[email protected]>
>> ---
>> 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) {
>