Re: [PATCH] ACPICA: Fix dispatcher timeout mechanism

[Bart Van Assche <bvanassche@acm.org>]

On Tue, 2018-10-16 at 07:04 +0200, Greg KH wrote:
> On Mon, Oct 15, 2018 at 04:01:35PM -0700, Bart Van Assche wrote:
> > On Tue, 2018-10-16 at 00:44 +0200, Rafael J. Wysocki wrote:
> > > On Tue, Oct 16, 2018 at 12:19 AM Bart Van Assche <bvanassche@acm.org> wrote:
> > > > 
> > > > This patch avoids that the following warning is reported during hibernation:
> > > 
> > > Well, what exactly is the problem and why is the patch the right way
> > > to address it?
> > 
> > It is not safe to call ktime_get() after having called timekeeping_suspend().
> > 
> > > >  /*
> > > > diff --git a/drivers/acpi/acpica/dscontrol.c b/drivers/acpi/acpica/dscontrol.c
> > > > index 0da96268deb5..9dbea4549484 100644
> > > > --- a/drivers/acpi/acpica/dscontrol.c
> > > > +++ b/drivers/acpi/acpica/dscontrol.c
> > > > @@ -84,8 +84,8 @@ acpi_ds_exec_begin_control_op(struct acpi_walk_state *walk_state,
> > > >                 control_state->control.package_end =
> > > >                     walk_state->parser_state.pkg_end;
> > > >                 control_state->control.opcode = op->common.aml_opcode;
> > > > -               control_state->control.loop_timeout = acpi_os_get_timer() +
> > > > -                   (u64)(acpi_gbl_max_loop_iterations * ACPI_100NSEC_PER_SEC);
> > > > +               control_state->control.loop_timeout = jiffies +
> > > > +                   acpi_gbl_max_loop_iterations * HZ;
> > > 
> > > jiffies is Linux-specific and so it should not be used in the ACPICA code.
> > 
> > Really? There is plenty of other ACPI code that uses the jiffies counter directly.
> > Why wouldn't it be allowed to use the jiffies counter in this context since there
> > is so much other ACPI code that uses that counter?
> 
> acpica is different from acpi.  It is the "core acpi code" that is
> shared across other operating systems.  That is why jiffies does not
> work in it :(

Thanks Greg for the feedback. I wasn't aware of the difference between ACPICA and
other ACPI code.

Bart.