Re: [PATCH v2] irqdomain: Auto-set IRQ_DOMAIN_FLAG_DESTROY_GC in __irq_domain_instantiate()

[Thomas Gleixner]

On Fri, Sep 04 2026 at 15:09, Qingshuang Fu wrote:
> When a driver uses irq_domain_instantiate() with dgc_info to create
> generic irq chips, the domain is expected to automatically clean up
> the generic chips when irq_domain_remove() is called. However,
> __irq_domain_instantiate() does not set the IRQ_DOMAIN_FLAG_DESTROY_GC
> flag which is required by irq_domain_remove() to trigger cleanup.
>
> Currently all existing callers of irq_domain_instantiate() with dgc_info
> manually set this flag, which is error-prone. If a future caller forgets to
> set the flag, generic chips allocated by irq_domain_alloc_generic_chips()
> will leak on domain removal.
>
> Set IRQ_DOMAIN_FLAG_DESTROY_GC right after irq_domain_alloc_generic_chips()
> succeeds inside __irq_domain_instantiate().
>
> This makes automatic cleanup the default for all users that provide
> dgc_info via irq_domain_instantiate().
>
> This is the correct location for several reasons:
> - irq_domain_instantiate() is a high-level wrapper which internally
>   allocates the generic chips, so it should also take responsibility
>   for arranging their cleanup.
> - Automatically setting the flag inside irq_domain_alloc_generic_chips()
>   would affect legacy callers like __irq_alloc_domain_generic_chips(),
>   some of which perform custom manual cleanup and could hit use-after-free.
>
> Fixes: e6f67ce32e8e ("irqdomain: Add support for generic irq chips creation before publishing a domain")

This does not fix anything.

All users which invoke irq_domain_instantiate() with info->dgc_info
populated set the flag, no?

And instead of adding a bogus Fixes tag, you could have made a series
which removes the redundant flag from the three perfectly fine working
drivers.