Re: [PATCH 1/2] virtio: console: Serialise control work

[Rusty Russell <rusty@xxxxxxxxxxxxxxx>]

On Fri,  6 Jan 2012 16:19:07 +0530, Amit Shah <amit.shah@xxxxxxxxxx> wrote:
> We currently allow multiple instances of the control work handler to run
> in parallel.  This isn't expected to work; serialise access by disabling
> interrupts on new packets from the Host and enable them when all the
> existing ones are consumed.
> 
> Testcase: hot-plug/unplug a port in a loop.  Without this patch, some
> sysfs warnings are seen along with freezes.  With the patch, all works
> fine.

Wait a sec... This might *work*, but it's not correct.  Remember that
disabling callbacks is a hint, and it's cetainly not synchronous.

You need something else to explicitly prevent reentry.

Unapplied,
Rusty.
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