Re: [PATCH] dovetail: Fix interrupt re-enabling after hibernation

[Philippe Gerum <rpm@xenomai.org>]

Florian Bezdeka <florian.bezdeka@siemens.com> writes:

> On Fri, 2025-03-21 at 08:51 +0100, Philippe Gerum wrote:
>> Jan Kiszka <jan.kiszka@siemens.com> writes:
>> 
>> > From: Jan Kiszka <jan.kiszka@siemens.com>
>> > 
>> > We had unbalanced hard_cond_local_irq_disable here so far.
>> > 
>> > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> > ---
>> > 
>> > Minus one hunk that is already in current 6.12.y, this needs to be 
>> > applied to older stable versions as well.
>> > 
>> >  kernel/power/hibernate.c | 3 +++
>> >  1 file changed, 3 insertions(+)
>> > 
>> > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
>> > index 733b1a196f09e..e1c05f276a453 100644
>> > --- a/kernel/power/hibernate.c
>> > +++ b/kernel/power/hibernate.c
>> > @@ -352,6 +352,7 @@ static int create_image(int platform_mode)
>> >  	syscore_resume();
>> >  
>> >   Enable_irqs:
>> > +	hard_cond_local_irq_enable();
>> >  	system_state = SYSTEM_RUNNING;
>> >  	local_irq_enable();
>> >  
>> > @@ -522,6 +523,7 @@ static int resume_target_kernel(bool platform_mode)
>> >  	syscore_resume();
>> >  
>> >   Enable_irqs:
>> > +	hard_cond_local_irq_enable();
>> >  	system_state = SYSTEM_RUNNING;
>> >  	local_irq_enable();
>> >  
>> > @@ -628,6 +630,7 @@ int hibernation_platform_enter(void)
>> >   Power_up:
>> >  	syscore_resume();
>> >   Enable_irqs:
>> > +	hard_cond_local_irq_enable();
>> >  	system_state = SYSTEM_RUNNING;
>> >  	local_irq_enable();
>> 
>> Merged into v6.12 and backported to v6.1.y-cip, thanks.
>
> Sorry, but I have to highlight that this patch does not help at all.
> Testing shows that we already "hang" when trying to hibernate. We never
> make it into the "wakeup" path.
>
> I think the "process" we followed here is broken. First we have to
> implement and *TEST* things in latest development branches and once we
> are sure we fully addressed the problem back porting can happen.

The point is that this has never been a new and/or untested feature, we
may be seeing a regression on all versions of a feature that did work
for ages, the story does not start with v6.14. Now, the tricky issue
with hibernation is not necessarily in the code paths above, but most
likely in one of the many suspend/resume handlers, which are per-driver
beasts. First of all, we need to define a test configuration with
suspend/resume code which is known to work.

-- 
Philippe.