Re: [patch] revert: [NET]: Fix races in net_rx_action vs netpoll

[Ingo Molnar <mingo@elte.hu>]

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

>    With MSI, edge-triggered interrupts are making a comeback in a big 
>    way, and yeah, e1000 is one of the drivers that do MSI. Ingo might 
>    want to confirm whether it's actually enabled for him, and whether 
>    turning it off might hide the problem, but if that's it, then the 
>    whole patch is fundamentally broken, and not worth saving.

MSI was off for the test:

  # CONFIG_PCI_MSI is not set

full config is at:

  http://redhat.com/~mingo/misc/config

the hang-log is at:

  http://redhat.com/~mingo/misc/hang.log

netconsole output went silent during the last tx-timeout message. (the 
above hang.log is from dmesg)

> but in either case (or, indeed, even if I didn't see any problem at 
> all), I think reverting a patch that isn't needed is _always_ the 
> right choice.
> 
> If we don't know what caused a problem in the first place, or if the 
> fix is known to be required for something else and reverting it would 
> cause *another* regression, it would be another issue. But as it is, 
> reverting it would seem to unquestionably get rid of a regression, and 
> is thus a no-brainer.
> 
> No?

i also offered to quickly try any test-version of the fixed patch, so 
there's a real and deterministic path towards fixing the patch. The 
regression is obvious and triggers all the time.

	Ingo