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FreeRTOS_send gets stuck replying 0

Posted by dibosco on August 30, 2016

Folks,

I have a situation where, ocassionally, FreeRTOS_send() returns 0.

I followed the premise on this page:

http://www.freertos.org/FreeRTOS-Plus/FreeRTOSPlusTCP/TCPNetworkingTutorialSendingTCP_Data.html

However, very ocassionally, I find that in this part:

if( FreeRTOSconnect( xSocket, &xRemoteAddress, sizeof( xRemoteAddress ) ) == 0 ) { /* Keep sending until the entire buffer has been sent. / while( xAlreadyTransmitted < xTotalLengthToSend ) { / How many bytes are left to send? */ xLenToSend = xTotalLengthToSend - xAlreadyTransmitted; xBytesSent = FreeRTOSsend( /* The socket being sent to. / xSocket, / The data being sent. / &( pcBufferToTransmit[ xAlreadyTransmitted ] ), / The remaining length of data to send. / xLenToSend, / ulFlags. */ 0 );

    if( xBytesSent >= 0 )
    {
        /* Data was sent successfully. */
        xAlreadyTransmitted += xBytesSent;
    }
    else
    {
        /* Error - break out of the loop for graceful socket close. */
        break;
    }
}

}

The xBytesSent is always zero and therefore the thread gets stuck infinitely in that bit of the code and the whole web server just stops responding,

I changed the line from:

if( xBytesSent >= 0 )

to

if( xBytesSent > 0 )

And that seems to stop the thread from locking up, but I very ocassionally get my auto-refresh page not responding and have to manually refresh the page, then all is well again.

I'm using a version of the TCP/IP stack that is around a year old. Is it worth updating it? Or do these symptoms point to something more sinister?

If it's of any help I did step into the code and found that the zero return value was here:

else if( pxSocket->u.xTcp.bits.bFinSent )
{
    /* This TCP connection is closing already, the FIN flag has been sent.
    Maybe it is still delivering or receiving data.
    Return OK in order not to get closed/deleted too quickly */
    xResult = 0;
}

Which is in prvTCPSendCheck() which is called by FreeRTOS_send().

Many thanks!

Rob


FreeRTOS_send gets stuck replying 0

Posted by heinbali01 on August 30, 2016

Hi Rob,

There is a newer release available of the +TCP library than the one that you are using:

http://www.freertos.org/FreeRTOS-Labs/RTOSlabsdownload.html

Just thinking out loud: if the FIN has been sent (bFinSent), then the connection is in a closing state. Apparently, the peer has not yet acknowledged the FIN, because ucTCPState != eCLOSED yet, the connection isn't closed.

It would be interesting to see a PCAP dump of that conversation in which send() hangs. Can you create that?

On itself, your code seems correct: eventually FreeRTOS_send() will either send all data, or the connection gets closed and FreeRTOS_send() will return a negative errno code.

If FreeRTOS_send() returns 0, it means that the buffers are full. Does the call still block when nothing can be sent? Isn't it just spinning around on a too high priority?

Do you have these enabled?

~~~~ #define ipconfigTCPHANGPROTECTION 1 #define ipconfigTCPKEEPALIVE 1 ~~~~

Not sure if it would help you with this problem though :-)

What does your code do after sending the file? After the last successful call to FreeRTOS_send()? Do you wait for the data to be properly delivered? Do you use the same socket for more transactions?

Regards.


FreeRTOS_send gets stuck replying 0

Posted by dibosco on September 1, 2016

Hi Hein,

I have attached an instance where the auto page request is sent out and nothing is returned to the browser.

Eventually, I hit the little x on the right of the URL bar in Firefox, re-request the page by hitting the curved arrow and it works fine.

In twenty minutes of the auto request page being active, it fails to reply once or twice.

I would say, this isn't sending a file, this is updating the web browser where the system is up to, when setting up the addresses on a pair of DALI buses. A process that takes around twenty minutes.

Both of those #defines are enabled, yes.

I'll try the latest version of the stack.

Thanks!

Rob

On 30/08/16 16:43, Hein Tibosch wrote: > Hi Rob, > > There is a newer release available of the +TCP library than the one that > you are using: > > http://www.freertos.org/FreeRTOS-Labs/RTOSlabsdownload.html > > Just thinking out loud: if the FIN has been sent (|bFinSent|), then the > connection is in a closing state. > Apparently, the peer has not yet acknowledged the FIN, because > |ucTCPState != eCLOSED| yet, the connection isn't closed. > > It would be interesting to see a PCAP dump of that conversation in which > send() hangs. Can you create that? > > On itself, your code seems correct: eventually |FreeRTOSsend()| will > either send all data, or the connection gets closed and > |FreeRTOSsend()| will return a negative errno code. > > If |FreeRTOSsend()| returns 0, it means that the buffers are full. Does > the call still block when nothing can be sent? Isn't it just spinning > around on a too high priority? > > Do you have these enabled? > > #define ipconfigTCPHANGPROTECTION 1 > #define ipconfigTCPKEEPALIVE 1 > > Not sure if it would help you with this problem though :-) > > What does your code do after sending the file? After the last successful > call to |FreeRTOSsend()|? Do you wait for the data to be properly > delivered? > Do you use the same socket for more transactions? > > Regards. > > ------------------------------------------------------------------------ > > FreeRTOS_send gets stuck replying 0 > https://sourceforge.net/p/freertos/discussion/382005/thread/07900148/?limit=25#ab7d > > ------------------------------------------------------------------------ > > Sent from sourceforge.net because you indicated interest in > https://sourceforge.net/p/freertos/discussion/382005/ > > To unsubscribe from further messages, please visit > https://sourceforge.net/auth/subscriptions/ >

Attachments


FreeRTOS_send gets stuck replying 0

Posted by heinbali01 on September 1, 2016

Hi Rob,

The PCAP shows a GET request that isn't responded to. The browser waits for 30 seconds and disconnects.

Things are still not clear to me :-(

I'll try the latest version of the stack.

Good idea. Make sure you get the latest, which is "160831FreeRTOSLabs.zip".

Regards.


FreeRTOS_send gets stuck replying 0

Posted by dibosco on September 2, 2016

Hi Hein,

I did update the stack and kernel from the link you sent and ran the cycle several times with no issues, so hopefully the new stack has done the trick!

Thanks!

Rob

On 02/09/16 00:34, Hein Tibosch wrote: > > Hi Rob, > > The PCAP shows a GET request that isn't responded to. The browser > waits for 30 seconds and disconnects. > > Things are still not clear to me :-( > > I'll try the latest version of the stack. > > Good idea. Make sure you get the latest, which is > "160831FreeRTOSLabs.zip". > > Regards. > > ------------------------------------------------------------------------ > > FreeRTOS_send gets stuck replying 0 > https://sourceforge.net/p/freertos/discussion/382005/thread/07900148/?limit=25#956f > > ------------------------------------------------------------------------ > > Sent from sourceforge.net because you indicated interest in > https://sourceforge.net/p/freertos/discussion/382005/ > > To unsubscribe from further messages, please visit > https://sourceforge.net/auth/subscriptions/ >

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