[PATCH 00/11] firmware: Convert to platform remove callback returning void

[PATCH 00/11] firmware: Convert to platform remove callback returning void

[Uwe Kleine-König]

Hello,

this series converts all platform drivers below drivers/firmware that
make use of .remove() to use .remove_new() instead.

See commit 5c5a7680e67b ("platform: Provide a remove callback that
returns no value") for an extended explanation and the eventual goal.
The TL;DR; is to make it harder for driver authors to leak resources
without noticing. The drivers here get it right though and so can be
converted trivially.

This is merge window material. There doesn't seem to be a maintainer for
all of drivers/firmware and I don't know how patch application works
there usually.  All patches are pairwise independent, so they can be
applied individually.

Best regards
Uwe

Uwe Kleine-König (11):
  firmware: arm_scmi: Convert to platform remove callback returning void
  firmware: arm_scpi: Convert to platform remove callback returning void
  firmware: coreboot_table: Convert to platform remove callback returning void
  firmware: imx-dsp: Convert to platform remove callback returning void
  firmware: mtk-adsp-ipc: Convert to platform remove callback returning void
  firmware: qemu_fw_cfg: Convert to platform remove callback returning void
  firmware: raspberrypi: Convert to platform remove callback returning void
  firmware: stratix10-rsu: Convert to platform remove callback returning void
  firmware: stratix10-svc: Convert to platform remove callback returning void
  firmware: turris-mox-rwtm: Convert to platform remove callback returning void
  firmware: zynqmp: Convert to platform remove callback returning void

 drivers/firmware/arm_scmi/driver.c       | 6 ++----
 drivers/firmware/arm_scpi.c              | 6 ++----
 drivers/firmware/google/coreboot_table.c | 5 ++---
 drivers/firmware/imx/imx-dsp.c           | 6 ++----
 drivers/firmware/mtk-adsp-ipc.c          | 6 ++----
 drivers/firmware/qemu_fw_cfg.c           | 5 ++---
 drivers/firmware/raspberrypi.c           | 6 ++----
 drivers/firmware/stratix10-rsu.c         | 5 ++---
 drivers/firmware/stratix10-svc.c         | 6 ++----
 drivers/firmware/turris-mox-rwtm.c       | 6 ++----
 drivers/firmware/xilinx/zynqmp.c         | 6 ++----
 11 files changed, 22 insertions(+), 41 deletions(-)

base-commit: 39676dfe52331dba909c617f213fdb21015c8d10
-- 
2.43.0

[PATCH 06/11] firmware: qemu_fw_cfg: Convert to platform remove callback returning void

[Uwe Kleine-König]

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.

To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new(), which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/firmware/qemu_fw_cfg.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index 1448f61173b3..03da9a4354f8 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -731,7 +731,7 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev)
 	return err;
 }
 
-static int fw_cfg_sysfs_remove(struct platform_device *pdev)
+static void fw_cfg_sysfs_remove(struct platform_device *pdev)
 {
 	pr_debug("fw_cfg: unloading.\n");
 	fw_cfg_sysfs_cache_cleanup();
@@ -739,7 +739,6 @@ static int fw_cfg_sysfs_remove(struct platform_device *pdev)
 	fw_cfg_io_cleanup();
 	fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
 	fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
-	return 0;
 }
 
 static const struct of_device_id fw_cfg_sysfs_mmio_match[] = {
@@ -758,7 +757,7 @@ MODULE_DEVICE_TABLE(acpi, fw_cfg_sysfs_acpi_match);
 
 static struct platform_driver fw_cfg_sysfs_driver = {
 	.probe = fw_cfg_sysfs_probe,
-	.remove = fw_cfg_sysfs_remove,
+	.remove_new = fw_cfg_sysfs_remove,
 	.driver = {
 		.name = "fw_cfg",
 		.of_match_table = fw_cfg_sysfs_mmio_match,
-- 
2.43.0

Re: [PATCH 06/11] firmware: qemu_fw_cfg: Convert to platform remove callback returning void

[Philippe Mathieu-Daudé]

On 27/12/23 17:26, Uwe Kleine-König wrote:
> The .remove() callback for a platform driver returns an int which makes
> many driver authors wrongly assume it's possible to do error handling by
> returning an error code. However the value returned is ignored (apart
> from emitting a warning) and this typically results in resource leaks.
> 
> To improve here there is a quest to make the remove callback return
> void. In the first step of this quest all drivers are converted to
> .remove_new(), which already returns void. Eventually after all drivers
> are converted, .remove_new() will be renamed to .remove().
> 
> Trivially convert this driver from always returning zero in the remove
> callback to the void returning variant.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>   drivers/firmware/qemu_fw_cfg.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Re: [PATCH 06/11] firmware: qemu_fw_cfg: Convert to platform remove callback returning void

[Michael S. Tsirkin]

On Wed, Dec 27, 2023 at 05:26:30PM +0100, Uwe Kleine-König wrote:
> The .remove() callback for a platform driver returns an int which makes
> many driver authors wrongly assume it's possible to do error handling by
> returning an error code. However the value returned is ignored (apart
> from emitting a warning) and this typically results in resource leaks.
> 
> To improve here there is a quest to make the remove callback return
> void. In the first step of this quest all drivers are converted to
> .remove_new(), which already returns void. Eventually after all drivers
> are converted, .remove_new() will be renamed to .remove().
> 
> Trivially convert this driver from always returning zero in the remove
> callback to the void returning variant.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

I don't mind.

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  drivers/firmware/qemu_fw_cfg.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
> index 1448f61173b3..03da9a4354f8 100644
> --- a/drivers/firmware/qemu_fw_cfg.c
> +++ b/drivers/firmware/qemu_fw_cfg.c
> @@ -731,7 +731,7 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev)
>  	return err;
>  }
>  
> -static int fw_cfg_sysfs_remove(struct platform_device *pdev)
> +static void fw_cfg_sysfs_remove(struct platform_device *pdev)
>  {
>  	pr_debug("fw_cfg: unloading.\n");
>  	fw_cfg_sysfs_cache_cleanup();
> @@ -739,7 +739,6 @@ static int fw_cfg_sysfs_remove(struct platform_device *pdev)
>  	fw_cfg_io_cleanup();
>  	fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
>  	fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
> -	return 0;
>  }
>  
>  static const struct of_device_id fw_cfg_sysfs_mmio_match[] = {
> @@ -758,7 +757,7 @@ MODULE_DEVICE_TABLE(acpi, fw_cfg_sysfs_acpi_match);
>  
>  static struct platform_driver fw_cfg_sysfs_driver = {
>  	.probe = fw_cfg_sysfs_probe,
> -	.remove = fw_cfg_sysfs_remove,
> +	.remove_new = fw_cfg_sysfs_remove,
>  	.driver = {
>  		.name = "fw_cfg",
>  		.of_match_table = fw_cfg_sysfs_mmio_match,
> -- 
> 2.43.0