linux-kernel - Re: [PATCH v3 10/11] cxl/acpi: Prepare use of EFI runtime services

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Message-ID: <aMsf7EP8W99QJFTI@gourry-fedora-PF4VCD3F>
Date: Wed, 17 Sep 2025 16:54:04 -0400
From: Gregory Price <gourry@...rry.net>
To: Robert Richter <rrichter@....com>
Cc: Alison Schofield <alison.schofield@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Ira Weiny <ira.weiny@...el.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Dave Jiang <dave.jiang@...el.com>,
	Davidlohr Bueso <dave@...olabs.net>, linux-cxl@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Fabio M. De Francesco" <fabio.m.de.francesco@...ux.intel.com>,
	Terry Bowman <terry.bowman@....com>,
	Joshua Hahn <joshua.hahnjy@...il.com>
Subject: Re: [PATCH v3 10/11] cxl/acpi: Prepare use of EFI runtime services

On Fri, Sep 12, 2025 at 04:45:12PM +0200, Robert Richter wrote:
> In order to use EFI runtime services, esp. ACPI PRM which uses the
> efi_rts_wq workqueue, initialize EFI before CXL ACPI.
> 
> There is a subsys_initcall order dependency if driver is builtin:
> 
>  subsys_initcall(cxl_acpi_init);
>  subsys_initcall(efisubsys_init);
> 
> Prevent the efi_rts_wq workqueue being used by cxl_acpi_init() before
> its allocation. Use subsys_initcall_sync(cxl_acpi_init) to always run
> efisubsys_init() first.
> 
> Reported-by: Gregory Price <gourry@...rry.net>
> Tested-by: Joshua Hahn <joshua.hahnjy@...il.com>
> Reviewed-by: Joshua Hahn <joshua.hahnjy@...il.com>

Reviewed-by: Gregory Price <gourry@...rry.net>

> Signed-off-by: Robert Richter <rrichter@....com>
> ---
>  drivers/cxl/acpi.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index 26c494704437..95a5ba395c1a 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -1012,8 +1012,12 @@ static void __exit cxl_acpi_exit(void)
>  	cxl_bus_drain();
>  }
>  
> -/* load before dax_hmem sees 'Soft Reserved' CXL ranges */
> -subsys_initcall(cxl_acpi_init);
> +/*
> + * Load before dax_hmem sees 'Soft Reserved' CXL ranges. Use
> + * subsys_initcall_sync() since there is an order dependency with
> + * subsys_initcall(efisubsys_init), which must run first.
> + */
> +subsys_initcall_sync(cxl_acpi_init);
>  
>  /*
>   * Arrange for host-bridge ports to be active synchronous with
> -- 
> 2.39.5
>