[Bug 996] DPDK:20.11.1: net/ena crash while fetching xstats

[bugzilla@dpdk.org]

https://bugs.dpdk.org/show_bug.cgi?id=996

Michal Krawczyk (mk@semihalf.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|WONTFIX                     |---
             Status|RESOLVED                    |UNCONFIRMED

--- Comment #3 from Michal Krawczyk (mk@semihalf.com) ---
Hey Amiya,

sorry for the late reply, I was OOO for one week.

Thank you for providing us with more details. 

If you aren't calling any API that needs to use the ENA admin queue from the
secondary process, the situation you're seeing shouldn't happen.

I just executed simple application on DPDK v20.11.1 in MP mode - the main
process is fetching the xstats, the secondary process is simply performing the
packets forwarding. The application is not crashing for my case.

From what I understand, the crash happens, because:

1. The ENA admin queue is not using the shared memory
2. The secondary process sends the request and saves it in the secondary
process memory
3. The primary process receives the interrupt and executes the completion
handler 
4. The completion handler cannot find the relevant request (as it's in the
secondary process memory) and the app crashes.

Please double check if:

1. The xstats aren't being fetched from the secondary process
2. You aren't calling any of API below from the secondary process, which also
uses the ENA admin queue:
  - rte_eth_dev_set_mtu()
  - rte_eth_dev_rss_reta_update()
  - rte_eth_dev_rss_reta_query()

The point 1. is much more likely as you've described it's a regression in
v20.11, and indeed - the xstats were extended after v19.11 release.

If none of the above is true, every other information that could potentially
get us closer to the core of the issue may be helpful (we can't reproduce this
on our side).

Thanks,
Michal

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