Re: [PATCH v3 06/10] ACPI: extlog: Defer CXL protocol error handling to avoid lock inversion

On Fri, Jul 17, 2026 at 09:16:43AM -0700, Dave Jiang wrote:
> sashiko-bot flagged an AB-BA deadlock between the PCI device_lock and
> the MCE decoder chain rwsem.
> 
> extlog_print() calls cxl_cper_handle_prot_err() synchronously while the
> MCE notifier chain rwsem is held, and that path takes the PCI device_lock
> via guard(device)(). The probe path takes the locks in the opposite
> order (device_lock held while mce_register_decode_chain() takes the
> rwsem), so the two form an AB-BA deadlock.
> 
> ghes.c already avoids this by posting protocol errors to a kfifo and
> handling them from a workqueue via cxl_cper_post_prot_err(). Export that
> function and use it from acpi_extlog.c instead of calling
> cxl_cper_handle_prot_err() directly.
> 
> Reported-by: [email protected]
> Link: https://lore.kernel.org/linux-cxl/[email protected]/
> Assisted-by: Claude:claude-sonnet-4-6
> Signed-off-by: Dave Jiang <[email protected]>

Reviewed-by: Alison Schofield <[email protected]>