[PATCH] tipc: set sk_err correctly when connection fails

From: Erik Hugne <redacted>

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 <redacted>
---
 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


------------------------------------------------------------------------------
Introducing Performance Central, a new site from SourceForge and 
AppDynamics. Performance Central is your source for news, insights, 
analysis and resources for efficient Application Performance Management. 
Visit us today!
http://pubads.g.doubleclick.net/gampad/clk?id=48897511&iu=/4140/ostg.clktrk

On 08/23/2013 09:56 PM, erik.hugne@ericsson.com wrote:

From: Erik Hugne <redacted>

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 <redacted>

Acked-by: Ying Xue <redacted>

On 13-08-23 09:56 AM, erik.hugne@ericsson.com wrote:

From: Erik Hugne <redacted>

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.
--

------------------------------------------------------------------------------
Introducing Performance Central, a new site from SourceForge and 
AppDynamics. Performance Central is your source for news, insights, 
analysis and resources for efficient Application Performance Management. 
Visit us today!
http://pubads.g.doubleclick.net/gampad/clk?id=48897511&iu=/4140/ostg.clktrk

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

On 13-08-27 11:18 AM, Erik Hugne wrote:

On Tue, Aug 27, 2013 at 09:20:23AM -0400, Paul Gortmaker wrote:

quoted

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

On 08/28/2013 02:12 AM, Paul Gortmaker wrote:

On 13-08-27 11:18 AM, Erik Hugne wrote:

quoted

On Tue, Aug 27, 2013 at 09:20:23AM -0400, Paul Gortmaker wrote:

quoted

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.
--

quoted

[...]
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