Re: [PATCH v2] irqchip: gic-v3-its: irq_pipeline: Fix OOB context in-band lock warning for ITS lock

On Thu, 2026-07-16 at 09:27 +0200, Florian Bezdeka wrote:
> On Tue, 2026-07-14 at 11:43 +0800, linz wrote:
> > Thank you for your feedback
>=20
> Welcome, but that shoudn't be part of the patch description.
>=20
> >=20
> > Under 6.6.63-dovetail2 environment, raw_spinlock_t for the ITS node loc=
k triggers out=E2=80=91of=E2=80=91band context warning in irq=E2=80=91pipel=
ine code.
> > As suggested by Florian, hybrid_spinlock_t should be limited to struct =
irq_desc and irqchip internals. ITS node lock is more suitable to use hard_=
spinlock_t.
> >=20
> > After replacing raw_spinlock_t with hard_spinlock_t, the call=E2=80=91t=
race warning disappears and system runs stably.
>=20
> Which warning? That should be part of the problem description here.
> (I know that it was part of some previous report/patch)
>=20
> >=20
> > In addition, the gic=E2=80=91v3 irqchip already has IRQCHIP_PIPELINE_SA=
FE flag, while its_irq_chip lacks this flag.
> > Enabling IRQCHIP_PIPELINE_SAFE for its_irq_chip has no effect to resolv=
e the warning.
>=20
> To my understanding gic-v3-its is kind of an extension to the gic-v3, so
> that gic-v3-its doesn't need to be flagged with IRQCHIP_PIPELINE_SAFE on
> its own. That part should be fine.
>=20
> The main question for me: Is it an invalid code path that we take or is
> the oob stage not properly synchronized with the inband code? I will try
> to find some time to look at this again. Meanwhile:
>=20
> Philippe, any comment on that?

I revisited v1 right ahead now. Link below.

I'm now quite sure that v2 is correct - code wise - but we should work
on a proper patch description. The description of v1 was quite good.

The raw_spinlock triggers a inband stage check that fires the warning
that was also part of v1. So we have a oob code path (hard IRQ masking)
using an inband only spinlock API. That's wrong and has to be fixed as
done in v2.

v1:
https://lore.kernel.org/xenomai/6ca12451-a015-4b54-9e22-0256e97d834e@siemen=
s.com/T/


Proposal for v3 patch description:

The warning shown below could be observed on dovetail 6.6.

The reason is the usage of a a raw_spinlock_t in hard IRQ masking code
path. A migration to hard_spinlock_t fixes this issue.

[    1.510903] IRQ pipeline: some code running in oob context 'Xenomai'
                             called an in-band only routine
[    1.510912] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G S                 6=
.6.63-dovetail2 #8
[    1.510918] Hardware name: Pe2204 DEMO DDR4 (DT)
[    1.510920] IRQ stage: Xenomai
[    1.510923] Call trace:
[    1.510926]  dump_backtrace+0x90/0xe4
[    1.510940]  show_stack+0x14/0x1c
[    1.510946]  dump_stack_lvl+0x84/0xc8
[    1.510953]  dump_stack+0x14/0x1c
[    1.510957]  check_inband_stage+0xb0/0xc8
[    1.510965]  inband_irq_save+0xc/0x28
[    1.510971]  _raw_spin_lock_irqsave+0x14/0x90
[    1.510977]  its_send_single_command+0x24/0x154
[    1.510984]  lpi_update_config+0x9c/0x144
[    1.510990]  its_mask_irq+0x2c/0x64
[    1.510997]  irq_chip_mask_parent+0x18/0x20
[    1.511005]  its_mask_msi_irq+0x1c/0x28
[    1.511012]  handle_fasteoi_irq+0x1cc/0x2b4
[    1.511016]  generic_pipeline_irq_desc+0x6c/0xa4
[    1.511021]  generic_handle_domain_irq+0x18/0x20
[    1.511028]  gic_handle_irq+0x4c/0x120
[    1.511032]  handle_irq_pipelined+0x40/0x64
[    1.511038]  call_on_irq_stack+0x24/0x30
[    1.511044]  do_interrupt_handler+0x138/0x158
[    1.511050]  el1_interrupt+0x40/0x110
[    1.511055]  el1h_64_irq_handler+0x14/0x1c
[    1.511061]  el1h_64_irq+0x64/0x68
[    1.511064]  default_idle_call+0x30/0x78
[    1.511071]  do_idle+0x128/0x150
[    1.511077]  cpu_startup_entry+0x34/0x38
[    1.511081]  kernel_init+0x0/0x1d4
[    1.511088]  arch_post_acpi_subsys_init+0x0/0x8
[    1.511096]  start_kernel+0x504/0x5cc
[    1.511103]  __primary_switched+0xbc/0xc4

>=20
> >=20
> > Signed-off-by: zhanglin <[email protected]>
> > ---
> >  drivers/irqchip/irq-gic-v3-its.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >=20
> > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic=
-v3-its.c
> > index 0e57735eac..3f2b02b8f4 100644
> > --- a/drivers/irqchip/irq-gic-v3-its.c
> > +++ b/drivers/irqchip/irq-gic-v3-its.c
> > @@ -94,7 +94,7 @@ struct its_device;
> >   * list.
> >   */
> >  struct its_node {
> > -	raw_spinlock_t		lock;
> > +	hard_spinlock_t		lock;
> >  	struct mutex		dev_alloc_lock;
> >  	struct list_head	entry;
> >  	void __iomem		*base;
> > --=20
> > 2.34.1