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Altera_Forum
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21 years ago

uC/OS-II LWIP pbuf_free fail

Has any one seen an issue with the following error durring run time: Assertion "pbuf_free: p->ref > 0" failed at line 567 in /cygdrive/c/applications /altera/kits/nios2/components/altera_lwip...
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Altera_Forum
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20 years ago

Does anyone know if this bug is also present in NIOS-II 1.1?

In the lwIP support forum several posts relating to some not yet solved pbuff issues can be read, including at least one that could produce a "pbuf_free: p->ref > 0" assertion.

Working in an FTP client, based on lwIP + uC/OS-II, we found that several pbuff related issues could arise when deleting a connection while lwIP was still trying to send un-acked TCP packets. A network sniffer was a great help for detecting that this was the cause.

Waiting for all the packets (in the connection) being send and acked (or timed-out) was the work-around. The connection object has two fields that are not NULL when packets are still pending (waiting to be sent or acked).