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

From: Ingo Molnar
Date: Mon Jul 16 2007 - 17:51:39 EST



* Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> 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
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