netdev - Re: [PATCH] net/tg3: fix race condition in tg3_reset_task

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Message-ID: <6852b406-1301-4570-b448-6fd58694d219@linux.vnet.ibm.com>
Date: Tue, 31 Oct 2023 18:18:14 -0500
From: Thinh Tran <thinhtr@...ux.vnet.ibm.com>
To: Pavan Chebbi <pavan.chebbi@...adcom.com>
Cc: netdev@...r.kernel.org, siva.kallam@...adcom.com, prashant@...adcom.com,
        mchan@...adcom.com, drc@...ux.vnet.ibm.com,
        Venkata Sai Duggi <venkata.sai.duggi@....com>
Subject: Re: [PATCH] net/tg3: fix race condition in tg3_reset_task_cancel()

Thanks for the review and I apologize for the delayed response. I had 
some trouble accessing the system, which delayed my investigation.

On 10/2/2023 11:34 PM, Pavan Chebbi wrote:
> 
> Can you elaborate on the race condition please? Are you saying
> tg3_reset_task_cancel() cleared the flag and tg3_tx_recover() set it
> again and the reset task never got a chance to run?
> Is that what is leading to TX stall?

This code path only triggered once, and after updating both the system 
and adapter firmware, I haven't encountered it again. However, the race 
condition issue still persists, causing the interfaces to go down.

Implementing the memory barrier, smp_mb__after_atomic(), as suggested by 
Michael Chan, the intermittent problem still persists. Upon closer 
investigation, I identified the root cause, details in the next version 
of the patch. When I commented out the call to the tg3_dump_state() 
function in the tg3_tx_timeout() function, the issue occurred quicker.

I'm working on submitting the v2 of the patch.

Regards,
Thinh Tran