RE: iflib_timer() vs ixl_admin_timer() race

From: Galazka, Krzysztof <>
Date: Fri, 14 Jan 2022 23:28:55 UTC
> -----Original Message-----
> From: Alexander Motin <> On Behalf Of Alexander Motin
> Sent: Wednesday, January 12, 2022 6:16 PM
> Subject: Re: iflib_timer() vs ixl_admin_timer() race
> Grepping now for iflib_admin_intr_deferred() through the sources I see
> the same issue in other Intel NIC drivers, plus bnxt(4).  So the main
> controversy I see is this: either admin intr should not stop and restart
> the callouts (and then question is why it does that now), or if it
> should be so heavy-weight, it should not be called so regularly (and
> then question why so many drivers do it).

I think the reason for stopping the callouts is the queue hang check,
which is done in them. Running IFDI_UPDATE_ADMIN_STATUS(ctx)
or IFDI_WATCHDOG_RESET(ctx) in parallel could lead to false positives.

As for the second part, not all cases, when admin task is scheduled
by timers, look justified. 
> In few drivers I've found it even more interesting: iflib_timer() calls
> IFDI_TIMER(), which calls ixgbe_if_timer(), which calls
> iflib_admin_intr_deferred(), which in its turn restart the
> iflib_timer().  Ouroboros. ;)

Yeah, that does not look right. I guess the intention was to fire off
the task only when link state change is detected, but I need to
double check that.


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