[PATCH] tipc: set sk_err correctly when connection fails

[PATCH] tipc: set sk_err correctly when connection fails

[erik.hugne]

From: Erik Hugne <erik.hugne@ericsson.com>

This fixes a problem when connect() fails and returns the error
code as a positive value, whereas errno itself is never set. The
reason is that error codes set in sk_err should never be inverted.

Signed-off-by: Erik Hugne <erik.hugne@ericsson.com>
---
 net/tipc/socket.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index ce8249c..6cc7ddd 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1257,7 +1257,7 @@ static u32 filter_connect(struct tipc_sock *tsock, struct sk_buff **buf)
 		/* Accept only ACK or NACK message */
 		if (unlikely(msg_errcode(msg))) {
 			sock->state = SS_DISCONNECTING;
-			sk->sk_err = -ECONNREFUSED;
+			sk->sk_err = ECONNREFUSED;
 			retval = TIPC_OK;
 			break;
 		}
@@ -1268,7 +1268,7 @@ static u32 filter_connect(struct tipc_sock *tsock, struct sk_buff **buf)
 		res = auto_connect(sock, msg);
 		if (res) {
 			sock->state = SS_DISCONNECTING;
-			sk->sk_err = res;
+			sk->sk_err = -res;
 			retval = TIPC_OK;
 			break;
 		}
-- 
1.7.9.5


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Re: [PATCH] tipc: set sk_err correctly when connection fails

[Ying Xue]

On 08/23/2013 09:56 PM, erik.hugne@ericsson.com wrote:
> From: Erik Hugne <erik.hugne@ericsson.com>
> 
> This fixes a problem when connect() fails and returns the error
> code as a positive value, whereas errno itself is never set. The
> reason is that error codes set in sk_err should never be inverted.
> 
> Signed-off-by: Erik Hugne <erik.hugne@ericsson.com>

Acked-by: Ying Xue <ying.xue@windriver.com>

> ---
>  net/tipc/socket.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/tipc/socket.c b/net/tipc/socket.c
> index ce8249c..6cc7ddd 100644
> --- a/net/tipc/socket.c
> +++ b/net/tipc/socket.c
> @@ -1257,7 +1257,7 @@ static u32 filter_connect(struct tipc_sock *tsock, struct sk_buff **buf)
>  		/* Accept only ACK or NACK message */
>  		if (unlikely(msg_errcode(msg))) {
>  			sock->state = SS_DISCONNECTING;
> -			sk->sk_err = -ECONNREFUSED;
> +			sk->sk_err = ECONNREFUSED;
>  			retval = TIPC_OK;
>  			break;
>  		}
> @@ -1268,7 +1268,7 @@ static u32 filter_connect(struct tipc_sock *tsock, struct sk_buff **buf)
>  		res = auto_connect(sock, msg);
>  		if (res) {
>  			sock->state = SS_DISCONNECTING;
> -			sk->sk_err = res;
> +			sk->sk_err = -res;
>  			retval = TIPC_OK;
>  			break;
>  		}
> 

Re: [PATCH] tipc: set sk_err correctly when connection fails

[Paul Gortmaker]

On 13-08-23 09:56 AM, erik.hugne@ericsson.com wrote:
> From: Erik Hugne <erik.hugne@ericsson.com>
> 
> This fixes a problem when connect() fails and returns the error
> code as a positive value, whereas errno itself is never set. The
> reason is that error codes set in sk_err should never be inverted.

That seems consistent with the other instances at least.

~/git/linux-head$ git grep ECONNREFUSED net|grep sk_err
net/caif/caif_socket.c:		cf_sk->sk.sk_err = ECONNREFUSED;
net/decnet/dn_nsp_in.c:		sk->sk_err = ECONNREFUSED;
net/ipv4/tcp_input.c:		sk->sk_err = ECONNREFUSED;
net/tipc/socket.c:			sk->sk_err = -ECONNREFUSED;
~/git/linux-head$

What was the high level user visible symptom in this case?
Stalled connections or ... ?

Thanks,
Paul.
--

> 
> Signed-off-by: Erik Hugne <erik.hugne@ericsson.com>
> ---
>  net/tipc/socket.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/tipc/socket.c b/net/tipc/socket.c
> index ce8249c..6cc7ddd 100644
> --- a/net/tipc/socket.c
> +++ b/net/tipc/socket.c
> @@ -1257,7 +1257,7 @@ static u32 filter_connect(struct tipc_sock *tsock, struct sk_buff **buf)
>  		/* Accept only ACK or NACK message */
>  		if (unlikely(msg_errcode(msg))) {
>  			sock->state = SS_DISCONNECTING;
> -			sk->sk_err = -ECONNREFUSED;
> +			sk->sk_err = ECONNREFUSED;
>  			retval = TIPC_OK;
>  			break;
>  		}
> @@ -1268,7 +1268,7 @@ static u32 filter_connect(struct tipc_sock *tsock, struct sk_buff **buf)
>  		res = auto_connect(sock, msg);
>  		if (res) {
>  			sock->state = SS_DISCONNECTING;
> -			sk->sk_err = res;
> +			sk->sk_err = -res;
>  			retval = TIPC_OK;
>  			break;
>  		}
> 

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Re: [PATCH] tipc: set sk_err correctly when connection fails

[Erik Hugne]

On Tue, Aug 27, 2013 at 09:20:23AM -0400, Paul Gortmaker wrote:
> What was the high level user visible symptom in this case?
> Stalled connections or ... ?

Should the connect fail, if the publication/server is unavailable or some other
error. The connect() call returns the error code directly (as a positive value).

[...]
socket(0x1e /* PF_??? */, SOCK_SEQPACKET, 0) = 3
setsockopt(3, 0x10f /* SOL_?? */, 129, [0], 4) = 0
setsockopt(3, 0x10f /* SOL_?? */, 127, [0], 4) = 0
connect(3, {sa_family=0x1e /* AF_??? */, sa_data="\2\1\322\4\0\0\322\4\0\0\0\0\0\0"}, 16) = 111
sendto(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 66000, 0, NULL, 0) = -1 EPIPE (Broken pipe)

In the strace above, error checking was done as:
if (connect(fd,.....) < 0)
    perror("connect");

//E

Re: [PATCH] tipc: set sk_err correctly when connection fails

[Paul Gortmaker]

On 13-08-27 11:18 AM, Erik Hugne wrote:
> On Tue, Aug 27, 2013 at 09:20:23AM -0400, Paul Gortmaker wrote:
>> What was the high level user visible symptom in this case?
>> Stalled connections or ... ?
> 
> Should the connect fail, if the publication/server is unavailable or some other
> error. The connect() call returns the error code directly (as a positive value).

Please send a v2 with the end-user visible symptom clearly described;
as this information is what people use in order to triage whether
commits belong in stable, or net vs. net-next etc.   For example:

  Should the connect fail, say if the publication/server is unavailable or
  some other error, then the code returns a positive return value.  Since
  most code only checks for a negative return on connect(), it tries to
  continue, but will ultimately fail on the 1st sendto() as the strace
  snippet below shows.

I've said "most code" since I simply don't know what it was that you were
tracing below.  It would help if we knew if this part of a common application
or similar.

Thanks,
Paul.
--

> 
> [...]
> socket(0x1e /* PF_??? */, SOCK_SEQPACKET, 0) = 3
> setsockopt(3, 0x10f /* SOL_?? */, 129, [0], 4) = 0
> setsockopt(3, 0x10f /* SOL_?? */, 127, [0], 4) = 0
> connect(3, {sa_family=0x1e /* AF_??? */, sa_data="\2\1\322\4\0\0\322\4\0\0\0\0\0\0"}, 16) = 111
> sendto(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 66000, 0, NULL, 0) = -1 EPIPE (Broken pipe)
> 
> In the strace above, error checking was done as:
> if (connect(fd,.....) < 0)
>     perror("connect");
> 
> //E
> 

Re: [PATCH] tipc: set sk_err correctly when connection fails

[Ying Xue]

On 08/28/2013 02:12 AM, Paul Gortmaker wrote:
> On 13-08-27 11:18 AM, Erik Hugne wrote:
>> On Tue, Aug 27, 2013 at 09:20:23AM -0400, Paul Gortmaker wrote:
>>> What was the high level user visible symptom in this case?
>>> Stalled connections or ... ?
>>
>> Should the connect fail, if the publication/server is unavailable or some other
>> error. The connect() call returns the error code directly (as a positive value).
> 
> Please send a v2 with the end-user visible symptom clearly described;
> as this information is what people use in order to triage whether
> commits belong in stable, or net vs. net-next etc.   For example:
> 
>   Should the connect fail, say if the publication/server is unavailable or
>   some other error, then the code returns a positive return value.  Since
>   most code only checks for a negative return on connect(), it tries to
>   continue, but will ultimately fail on the 1st sendto() as the strace
>   snippet below shows.
> 
> I've said "most code" since I simply don't know what it was that you were
> tracing below.  It would help if we knew if this part of a common application
> or similar.
> 

Firstly it's absolutely wrong that connect() returns a positive error
code - 111(i.e, ECONNREFUSED) if connect() is failed, that is, it
violates POSIX standard.

As the patch's changelog describes, sk_err is incorrectly set to a
negative value instead of positive value in filter_connect(). In
connect(), it will set its return value with sock_error(sk) if it fails.
As the return value of sock_error(sk) almost can be deemed as -sk_err,
this is why we see a positive error code of connect() in below strace log.

But, the patch is absolutely able to fix the issue.

Regards,
Ying

> Thanks,
> Paul.
> --
> 
>>
>> [...]
>> socket(0x1e /* PF_??? */, SOCK_SEQPACKET, 0) = 3
>> setsockopt(3, 0x10f /* SOL_?? */, 129, [0], 4) = 0
>> setsockopt(3, 0x10f /* SOL_?? */, 127, [0], 4) = 0
>> connect(3, {sa_family=0x1e /* AF_??? */, sa_data="\2\1\322\4\0\0\322\4\0\0\0\0\0\0"}, 16) = 111
>> sendto(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 66000, 0, NULL, 0) = -1 EPIPE (Broken pipe)
>>
>> In the strace above, error checking was done as:
>> if (connect(fd,.....) < 0)
>>     perror("connect");
>>
>> //E
>>
> 
>