[PATCH 00/20] mtd: Convert to platform remove callback returning void

[PATCH 00/20] mtd: Convert to platform remove callback returning void

[Uwe Kleine-König]

Hello,

this series converts all platform drivers below drivers/mtd to use the
.remove_new() callback. Compared to the traditional .remove() callback
.remove_new() returns no value. This is a good thing because the driver
core doesn't (and cannot) cope for errors during remove. The only effect
of a non-zero return value in .remove() is that the driver core emits a
warning. The device is removed anyhow and an early return from .remove()
usually yields resource leaks and/or use-after-free bugs.

All drivers touched here returned zero unconditionally in their remove
callback, so they could all be converted trivially to .remove_new().

See commit 5c5a7680e67b ("platform: Provide a remove callback that
returns no value") for an extended explanation and the eventual goal.

As an added bonus the series starts with a minor fix and a
simplification of the txx9ndfmc driver.

The only interdependencies in this series is between the three txx9ndfmc
patches. As there are still quite a few drivers to convert, I'm happy
about every patch that makes it in. So even if there is a merge conflict
with one patch until you apply (or a different concern that doesn't
apply to all patches), please apply the remainder of this series anyhow.
I'll come back to the part that you (maybe) skipped at a later point.

Best regards
Uwe

Uwe Kleine-König (20):
  mtd: rawnand: txx9ndfmc: Mark driver struct with __refdata to prevent
    section mismatch warning
  mtd: rawnand: txx9ndfmc: Drop if block with always false condition
  mtd: bcm47xxsflash: Convert to platform remove callback returning void
  mtd: docg3: Convert to platform remove callback returning void
  mtd: phram: Convert to platform remove callback returning void
  mtd: powernv_flash: Convert to platform remove callback returning void
  mtd: spear_smi: Convert to platform remove callback returning void
  mtd: st_spi_fsm: Convert to platform remove callback returning void
  mtd: hyperbus: hbmc-am654: Convert to platform remove callback
    returning void
  mtd: hyperbus: rpc-if: Convert to platform remove callback returning
    void
  mtd: lpddr2_nvm: Convert to platform remove callback returning void
  mtd: maps: lantiq-flash: Convert to platform remove callback returning
    void
  mtd: maps: physmap-core: Convert to platform remove callback returning
    void
  mtd: maps: plat-ram: Convert to platform remove callback returning
    void
  mtd: maps: pxa2xx-flash: Convert to platform remove callback returning
    void
  mtd: maps: sa1100-flash: Convert to platform remove callback returning
    void
  mtd: maps: sun_uflash: Convert to platform remove callback returning
    void
  mtd: rawnand: txx9ndfmc: Convert to platform remove callback returning
    void
  mtd: spi-nor: hisi-sfc: Convert to platform remove callback returning
    void
  mtd: spi-nor: nxp-spifi: Convert to platform remove callback returning
    void

 drivers/mtd/devices/bcm47xxsflash.c         |  6 ++----
 drivers/mtd/devices/docg3.c                 |  5 ++---
 drivers/mtd/devices/phram.c                 |  6 ++----
 drivers/mtd/devices/powernv_flash.c         |  6 ++----
 drivers/mtd/devices/spear_smi.c             |  6 ++----
 drivers/mtd/devices/st_spi_fsm.c            |  6 ++----
 drivers/mtd/hyperbus/hbmc-am654.c           |  6 ++----
 drivers/mtd/hyperbus/rpc-if.c               |  6 ++----
 drivers/mtd/lpddr/lpddr2_nvm.c              |  6 ++----
 drivers/mtd/maps/lantiq-flash.c             |  6 ++----
 drivers/mtd/maps/physmap-core.c             |  5 ++---
 drivers/mtd/maps/plat-ram.c                 |  8 +++-----
 drivers/mtd/maps/pxa2xx-flash.c             |  5 ++---
 drivers/mtd/maps/sa1100-flash.c             |  6 ++----
 drivers/mtd/maps/sun_uflash.c               |  6 ++----
 drivers/mtd/nand/raw/txx9ndfmc.c            | 15 +++++++++------
 drivers/mtd/spi-nor/controllers/hisi-sfc.c  |  5 ++---
 drivers/mtd/spi-nor/controllers/nxp-spifi.c |  6 ++----
 18 files changed, 44 insertions(+), 71 deletions(-)


base-commit: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d
-- 
2.40.1

[PATCH 06/20] mtd: powernv_flash: 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/mtd/devices/powernv_flash.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/devices/powernv_flash.c b/drivers/mtd/devices/powernv_flash.c
index 36e060386e59..66044f4f5bad 100644
--- a/drivers/mtd/devices/powernv_flash.c
+++ b/drivers/mtd/devices/powernv_flash.c
@@ -265,14 +265,12 @@ static int powernv_flash_probe(struct platform_device *pdev)
  *
  * Returns 0
  */
-static int powernv_flash_release(struct platform_device *pdev)
+static void powernv_flash_release(struct platform_device *pdev)
 {
 	struct powernv_flash *data = dev_get_drvdata(&(pdev->dev));
 
 	/* All resources should be freed automatically */
 	WARN_ON(mtd_device_unregister(&data->mtd));
-
-	return 0;
 }
 
 static const struct of_device_id powernv_flash_match[] = {
@@ -285,7 +283,7 @@ static struct platform_driver powernv_flash_driver = {
 		.name		= "powernv_flash",
 		.of_match_table	= powernv_flash_match,
 	},
-	.remove		= powernv_flash_release,
+	.remove_new	= powernv_flash_release,
 	.probe		= powernv_flash_probe,
 };
 
-- 
2.40.1

Re: [PATCH 00/20] mtd: Convert to platform remove callback returning void

[Tudor Ambarus]

On 10/8/23 21:01, Uwe Kleine-König wrote:
> Hello,
> 
> this series converts all platform drivers below drivers/mtd to use the
> .remove_new() callback. Compared to the traditional .remove() callback
> .remove_new() returns no value. This is a good thing because the driver
> core doesn't (and cannot) cope for errors during remove. The only effect
> of a non-zero return value in .remove() is that the driver core emits a
> warning. The device is removed anyhow and an early return from .remove()
> usually yields resource leaks and/or use-after-free bugs.
> 
> All drivers touched here returned zero unconditionally in their remove
> callback, so they could all be converted trivially to .remove_new().
> 
> See commit 5c5a7680e67b ("platform: Provide a remove callback that
> returns no value") for an extended explanation and the eventual goal.
> 

Acked-by: Tudor Ambarus <tudor.ambarus@linaro.org>

Re: [PATCH 06/20] mtd: powernv_flash: Convert to platform remove callback returning void

[Miquel Raynal]

On Sun, 2023-10-08 at 20:01:29 UTC, =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= 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>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.

Miquel