Re: [PATCH v2] core, x86: Add user return notifiers

From: Avi Kivity
Date: Thu Oct 01 2009 - 11:21:50 EST


On 09/22/2009 06:19 PM, H. Peter Anvin wrote:
Ingo Molnar wrote:
* Avi Kivity <avi@xxxxxxxxxx> wrote:

On 09/19/2009 09:40 AM, Avi Kivity wrote:
Add a general per-cpu notifier that is called whenever the kernel is
about to return to userspace. The notifier uses a thread_info flag
and existing checks, so there is no impact on user return or context
switch fast paths.
Ingo/Peter?

Would be nice to convert some existing open-coded return-to-user-space logic to this facility. One such candidate would be lockdep_sys_exit?

Ingo

Sorry, limited bandwidth due to LinuxCon, but I like the concept, and the previous (partial) patch was really clean. I agree with Ingo that arch support so we can use this as a general facility would be nice, but I don't consider that as a prerequisite for merging.

Re-ping?

If accepted, please merge just the core patch and I will carry all of them in parallel. Once tip is merged I'll drop my copy of the first patch.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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