[PATCH] ACPI: APEI: GHES: 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().

Instead of returning an error code, emit a better error message than the
core. Apart from the improved error message this patch has no effects
for the driver.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
---
Hello,

I tried to improve this driver before, see

	https://lore.kernel.org/linux-acpi/CAJZ5v0ifb-wvyp0JRq_4c1L6vTi_qEeXJ6P=Pmmq_56xRL74_A@mail.gmail.com
	https://lore.kernel.org/linux-arm-kernel/20221219221439.1681770-1-u.kleine-koenig@pengutronix.de
	https://lore.kernel.org/linux-arm-kernel/20221220154447.12341-1-u.kleine-koenig@pengutronix.de

but this didn't result in any patch being applied.

I think it's inarguable that there is a problem that wants to be fixed.
My tries to fix this problem fixxled out, so here comes a minimal change
that just points out the problem and otherwise makes ghes_remove()
return void without further side effects to allow me to continue my
quest to make platform_driver remove callbacks return no error.

Best regards
Uwe

 drivers/acpi/apei/ghes.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 63ad0541db38..dd8cd10b7809 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -1438,7 +1438,7 @@ static int ghes_probe(struct platform_device *ghes_dev)
 	return rc;
 }
 
-static int ghes_remove(struct platform_device *ghes_dev)
+static void ghes_remove(struct platform_device *ghes_dev)
 {
 	int rc;
 	struct ghes *ghes;
@@ -1475,8 +1475,15 @@ static int ghes_remove(struct platform_device *ghes_dev)
 		break;
 	case ACPI_HEST_NOTIFY_SOFTWARE_DELEGATED:
 		rc = apei_sdei_unregister_ghes(ghes);
-		if (rc)
-			return rc;
+		if (rc) {
+			/*
+			 * Returning early results in a resource leak, but we're
+			 * only here if stopping the hardware failed.
+			 */
+			dev_err(&ghes_dev->dev, "Failed to unregister ghes (%pe)\n",
+				ERR_PTR(rc));
+			return;
+		}
 		break;
 	default:
 		BUG();
@@ -1490,8 +1497,6 @@ static int ghes_remove(struct platform_device *ghes_dev)
 	mutex_unlock(&ghes_devs_mutex);
 
 	kfree(ghes);
-
-	return 0;
 }
 
 static struct platform_driver ghes_platform_driver = {
@@ -1499,7 +1504,7 @@ static struct platform_driver ghes_platform_driver = {
 		.name	= "GHES",
 	},
 	.probe		= ghes_probe,
-	.remove		= ghes_remove,
+	.remove_new	= ghes_remove,
 };
 
 void __init acpi_ghes_init(void)

base-commit: 5a82d69d48c82e89aef44483d2a129f869f3506a
-- 
2.42.0