Re: [PATCH v4] irqchip: gic-v3-its: irq_pipeline: Fix OOB context in-band lock warning for ITS lock

On Tue, 2026-08-04 at 16:53 +0800, linz wrote:
> The warning shown below could be observed on Dovetail 6.6 with arm64
> architecture when CONFIG_DEBUG_IRQ_PIPELINE is enabled.
> 
> The reason is the usage of 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
> 
> Beyond that, note that IRQ chip handlers such as irq_mask / irq_unmask run in
> OOB context. For instance, any code path calling lpi_update_config() must
> be oob‑capable, so gic_data_rdist_cpu(cpu)->rd_lock and its_vpe->vpe_lock are
> modified in this patch.
> 
> Convert:
> - its_node->lock
> - rdists.rd_lock
> - its_vpe->vpe_lock
> from raw_spinlock_t to hard_spinlock_t.
> 
> Signed-off-by: linz <[email protected]>
> ---
>  drivers/irqchip/irq-gic-v3-its.c   | 2 +-
>  include/linux/irqchip/arm-gic-v3.h | 2 +-
>  include/linux/irqchip/arm-gic-v4.h | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> 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;
> diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
> index 7286913654..9dcbf4b331 100644
> --- a/include/linux/irqchip/arm-gic-v3.h
> +++ b/include/linux/irqchip/arm-gic-v3.h
> @@ -613,7 +613,7 @@
>  
>  struct rdists {
>      struct {
> -        raw_spinlock_t    rd_lock;
> +        hard_spinlock_t    rd_lock;
>          void __iomem    *rd_base;
>          struct page    *pend_page;
>          phys_addr_t    phys_base;
> diff --git a/include/linux/irqchip/arm-gic-v4.h b/include/linux/irqchip/arm-gic-v4.h
> index bf9e064028..d7afd9d2cd 100644
> --- a/include/linux/irqchip/arm-gic-v4.h
> +++ b/include/linux/irqchip/arm-gic-v4.h
> @@ -68,7 +68,7 @@ struct its_vpe {
>       * Ensures mutual exclusion between affinity setting of the
>       * vPE and vLPI operations using vpe->col_idx.
>       */
> -    raw_spinlock_t        vpe_lock;
> +    hard_spinlock_t        vpe_lock;

Can you please share the call stack where this lock is involved in an
OOB code path?

The other two locks are fine. I'm unsure about this one here.

>      /*
>       * This collection ID is used to indirect the target
>       * redistributor for this VPE. The ID itself isn't involved in
> -- 
> 2.34.1