Re: [PATCH v15] x86/split_lock: Enable split lock detection by kernel

[Tony Luck]

On Sat, Jan 25, 2020 at 6:53 PM Luck, Tony <tony.luck@xxxxxxxxx> wrote:

> So why don't we come through __switch_to_xtra() when the spinner
> runs out its time slice (or the udelay interrupt happens and
> preempts the spinner)?

To close out this part of the thread. Linux doesn't call __switch_to_xtra()
in this case because I didn't ask it to. There are separate masks to check
TIF bits for the previous and next tasks in a context switch. I'd only set the
_TIF_SLD bit in the mask for the previous task.

See the v17 I posted a few hours before this message for the fix.

-Tony