Re: WARNING: suspicious RCU usage - sdhci-pltfm: SDHCI platform and OF driver helper

[Peter Zijlstra]

On Tue, Sep 01, 2020 at 09:13:40AM -0700, Paul E. McKenney wrote:
> On Tue, Sep 01, 2020 at 05:50:14PM +0200, peterz@xxxxxxxxxxxxx wrote:
> > On Tue, Sep 01, 2020 at 09:44:17AM -0600, Lina Iyer wrote:
> > > > > > > > I could add RCU_NONIDLE for the calls to pm_runtime_put_sync_suspend()
> > > > > > > > and pm_runtime_get_sync() in psci_enter_domain_idle_state(). Perhaps
> > > > > > > > that's the easiest approach, at least to start with.
> > 
> > > I think this would be nice. This should also cover the case, where PM domain
> > > power off notification callbacks call trace function internally. Right?
> > 
> > That's just more crap for me to clean up later :-(
> > 
> > trace_*_rcuidle() and RCU_NONIDLE() need to die, not proliferate.
> 
> Moving the idle-entry boundary further in is good in any number of ways.
> But experience indicates that no matter how far you move it, there will
> be something complex further in.  Unless you are pushing it all the way
> into all the arch-specific code down as far as it can possibly go?

Not all; the simple cpuidle drivers should be good already. The more
complicated ones need some help.

The patch provided earlier:

  https://lkml.kernel.org/r/20200901104206.GU1362448@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

should allow the complicated drivers to take over and DTRT.