[PATCH 01/20] mtd: rawnand: txx9ndfmc: Mark driver struct with __refdata to prevent section mismatch warning

[Arnd Bergmann]

On Mon, Oct 9, 2023, at 09:22, Masahiro Yamada wrote:
> On Mon, Oct 9, 2023 at 5:02 AM Uwe Kleine-König <u.kleine-koenig at pengutronix.de> wrote:
>>
>> As described in the added code comment, a reference to .exit.text is ok
>> for drivers registered via module_platform_driver_probe(). Make this
>> explicit to prevent a section mismatch warning with

>
> We have thousands of module_platform_drivers.
> I would be scared if they started to add __refdata.
>
> I am not sure if this is the right direction.

For a normal module_platform_driver(), this would indeed be
wrong, but as Uwe said above there is a special case for
module_platform_driver_probe(), which implicitly sets the
drv->driver.suppress_bind_attrs=true flag.

> In my understanding of the current DT overlay,
> there is no way to create/remove a platform device dynamically.
> I do not know if that will happen in the future.

For drivers without suppress_bind_attrs, you can manually
unbind the device from a driver, which in case of a loadable
module ends up calling the .remove callback (this is fine),
but in a built-in driver this would use a NULL pointer for
.remove and cause unexpected behavior.

This is the list of module_platform_driver_probe() instances
I found that have a .remove callback:

drivers/ata/pata_falcon.c-	.remove = __exit_p(pata_falcon_remove_one),
drivers/ata/pata_gayle.c-	.remove = __exit_p(pata_gayle_remove_one),
drivers/char/hw_random/mxc-rnga.c-	.remove = __exit_p(mxc_rnga_remove),
drivers/hwmon/mc13783-adc.c-	.remove_new	= mc13783_adc_remove,
drivers/input/mouse/amimouse.c-	.remove = __exit_p(amimouse_remove),
drivers/input/serio/q40kbd.c-	.remove_new	= q40kbd_remove,
drivers/input/touchscreen/mc13783_ts.c-	.remove_new	= mc13783_ts_remove,
drivers/leds/leds-mc13783.c-	.remove_new	= mc13xxx_led_remove,
drivers/media/platform/renesas/sh_vou.c:	.remove_new = sh_vou_remove,
drivers/media/rc/meson-ir-tx.c-	.remove_new = meson_irtx_remove,
drivers/memory/emif.c-	.remove		= __exit_p(emif_remove),
drivers/memory/ti-aemif.c-	.remove = aemif_remove,
drivers/memory/ti-emif-pm.c-	.remove = ti_emif_remove,
drivers/mtd/devices/docg3.c-	.remove		= docg3_release,
drivers/net/ethernet/broadcom/tg3.c-	.remove		= tg3_remove_one,
drivers/rapidio/switches/idt_gen3.c-	.remove = idtg3_remove,
drivers/video/fbdev/cg3.c-	.remove_new	= cg3_remove,
drivers/mtd/nand/raw/fsmc_nand.c-	.remove_new = fsmc_nand_remove,
drivers/mtd/nand/raw/orion_nand.c-	.remove_new	= orion_nand_remove,
drivers/mtd/nand/raw/sh_flctl.c-	.remove_new	= flctl_remove,
drivers/mtd/nand/raw/txx9ndfmc.c-	.remove		= __exit_p(txx9ndfmc_remove),
drivers/net/ethernet/cirrus/cs89x0.c-	.remove_new = cs89x0_platform_remove,
drivers/parport/parport_amiga.c-	.remove = __exit_p(amiga_parallel_remove),
drivers/power/reset/at91-poweroff.c-	.remove = __exit_p(at91_poweroff_remove),
drivers/power/reset/at91-reset.c-	.remove = __exit_p(at91_reset_remove),
drivers/power/reset/at91-sama5d2_shdwc.c-	.remove = __exit_p(at91_shdwc_remove),
drivers/rtc/rtc-at91rm9200.c-	.remove		= __exit_p(at91_rtc_remove),
drivers/rtc/rtc-at91sam9.c-	.remove_new	= at91_rtc_remove,
drivers/rtc/rtc-ftrtc010.c-	.remove_new	= ftrtc010_rtc_remove,
drivers/rtc/rtc-imxdi.c-	.remove = __exit_p(dryice_rtc_remove),
drivers/rtc/rtc-mc13xxx.c-	.remove_new = mc13xxx_rtc_remove,
drivers/rtc/rtc-mv.c-	.remove		= __exit_p(mv_rtc_remove),
drivers/rtc/rtc-pcap.c-	.remove = __exit_p(pcap_rtc_remove),
drivers/rtc/rtc-pxa.c-	.remove		= __exit_p(pxa_rtc_remove),
drivers/rtc/rtc-sh.c-	.remove		= __exit_p(sh_rtc_remove),
drivers/scsi/a3000.c-	.remove = __exit_p(amiga_a3000_scsi_remove),
drivers/scsi/a4000t.c-	.remove = __exit_p(amiga_a4000t_scsi_remove),
drivers/scsi/atari_scsi.c-	.remove = __exit_p(atari_scsi_remove),
drivers/scsi/mac_scsi.c-	.remove = __exit_p(mac_scsi_remove),
drivers/scsi/sun3_scsi.c-	.remove = __exit_p(sun3_scsi_remove),
drivers/tty/amiserial.c-	.remove = __exit_p(amiga_serial_remove),
drivers/usb/gadget/udc/at91_udc.c-	.remove		= at91udc_remove,
drivers/staging/emxx_udc/emxx_udc.c-	.remove_new	= nbu2ss_drv_remove,
drivers/usb/gadget/udc/aspeed_udc.c-	.remove			= ast_udc_remove,
drivers/usb/gadget/udc/at91_udc.c-	.remove		= at91udc_remove,
drivers/usb/gadget/udc/atmel_usba_udc.c-	.remove_new	= usba_udc_remove,
drivers/usb/gadget/udc/bcm63xx_udc.c-	.remove_new	= bcm63xx_udc_remove,
drivers/usb/gadget/udc/dummy_hcd.c-	.remove_new	= dummy_udc_remove,
drivers/usb/gadget/udc/fsl_qe_udc.c-	.remove_new     = qe_udc_remove,
drivers/usb/gadget/udc/fsl_udc_core.c-	.remove		= fsl_udc_remove,
drivers/usb/gadget/udc/lpc32xx_udc.c-	.remove		= lpc32xx_udc_remove,
drivers/usb/gadget/udc/mv_udc_core.c-	.remove_new	= mv_udc_remove,
drivers/usb/gadget/udc/omap_udc.c-	.remove_new	= omap_udc_remove,
drivers/usb/gadget/udc/pch_udc.c-	.remove =	pch_udc_remove,
drivers/usb/gadget/udc/pxa25x_udc.c-	.remove		= pxa25x_udc_remove,
drivers/usb/gadget/udc/pxa27x_udc.c-	.remove_new	= pxa_udc_remove,
drivers/usb/gadget/udc/renesas_usbf.c-	.remove_new     = usbf_remove,
drivers/usb/gadget/udc/tegra-xudc.c-	.remove_new = tegra_xudc_remove,
drivers/usb/gadget/udc/udc-xilinx.c-	.remove_new = xudc_remove,
drivers/usb/usbip/vudc_main.c-	.remove		= vudc_remove,
drivers/usb/gadget/udc/fusb300_udc.c-	.remove_new =	fusb300_remove,
drivers/usb/gadget/udc/lpc32xx_udc.c-	.remove		= lpc32xx_udc_remove,
drivers/usb/gadget/udc/m66592-udc.c-	.remove_new =	m66592_remove,
drivers/usb/gadget/udc/r8a66597-udc.c-	.remove_new =	r8a66597_remove,
drivers/usb/host/r8a66597-hcd.c-	.remove_new =	r8a66597_remove,
drivers/video/fbdev/amifb.c-	.remove = __exit_p(amifb_remove),
drivers/video/fbdev/atmel_lcdfb.c-	.remove		= __exit_p(atmel_lcdfb_remove),
drivers/video/fbdev/omap2/omapfb/vrfb.c-	.remove		= __exit_p(vrfb_remove),
drivers/virt/coco/sev-guest/sev-guest.c-	.remove		= __exit_p(sev_guest_remove),
drivers/watchdog/at91rm9200_wdt.c-	.remove_new	= at91wdt_remove,
drivers/watchdog/at91sam9_wdt.c-	.remove		= __exit_p(at91wdt_remove),
drivers/watchdog/txx9wdt.c-	.remove = __exit_p(txx9wdt_remove),

Out of these, only 29 have the .remove callback in the .exit.text section,
and they all use __exit_p:

drivers/ata/pata_falcon.c:static int __exit pata_falcon_remove_one(struct platform_device *pdev)
drivers/ata/pata_gayle.c:static int __exit pata_gayle_remove_one(struct platform_device *pdev)
drivers/char/hw_random/mxc-rnga.c:static int __exit mxc_rnga_remove(struct platform_device *pdev)
drivers/input/mouse/amimouse.c:static int __exit amimouse_remove(struct platform_device *pdev)
drivers/memory/emif.c:static int __exit emif_remove(struct platform_device *pdev)
drivers/mtd/nand/raw/txx9ndfmc.c:static int __exit txx9ndfmc_remove(struct platform_device *dev)
drivers/parport/parport_amiga.c:static int __exit amiga_parallel_remove(struct platform_device *pdev)
drivers/power/reset/at91-poweroff.c:static int __exit at91_poweroff_remove(struct platform_device *pdev)
drivers/power/reset/at91-reset.c:static int __exit at91_reset_remove(struct platform_device *pdev)
drivers/power/reset/at91-sama5d2_shdwc.c:static int __exit at91_shdwc_remove(struct platform_device *pdev)
drivers/rtc/rtc-at91rm9200.c:static int __exit at91_rtc_remove(struct platform_device *pdev)
drivers/rtc/rtc-imxdi.c:static int __exit dryice_rtc_remove(struct platform_device *pdev)
drivers/rtc/rtc-mv.c:static int __exit mv_rtc_remove(struct platform_device *pdev)
drivers/rtc/rtc-pcap.c:static int __exit pcap_rtc_remove(struct platform_device *pdev)
drivers/rtc/rtc-pxa.c:static int __exit pxa_rtc_remove(struct platform_device *pdev)
drivers/rtc/rtc-sh.c:static int __exit sh_rtc_remove(struct platform_device *pdev)
drivers/scsi/a3000.c:static int __exit amiga_a3000_scsi_remove(struct platform_device *pdev)
drivers/scsi/a4000t.c:static int __exit amiga_a4000t_scsi_remove(struct platform_device *pdev)
drivers/scsi/atari_scsi.c:static int __exit atari_scsi_remove(struct platform_device *pdev)
drivers/scsi/mac_scsi.c:static int __exit mac_scsi_remove(struct platform_device *pdev)
drivers/scsi/sun3_scsi.c:static int __exit sun3_scsi_remove(struct platform_device *pdev)
drivers/tty/amiserial.c:static int __exit amiga_serial_remove(struct platform_device *pdev)
drivers/video/fbdev/amifb.c:static int __exit amifb_remove(struct platform_device *pdev)
drivers/video/fbdev/atmel_lcdfb.c:static int __exit atmel_lcdfb_remove(struct platform_device *pdev)
drivers/video/fbdev/omap2/omapfb/vrfb.c:static void __exit vrfb_remove(struct platform_device *pdev)
drivers/virt/coco/sev-guest/sev-guest.c:static int __exit sev_guest_remove(struct platform_device *pdev)
drivers/watchdog/at91sam9_wdt.c:static int __exit at91wdt_remove(struct platform_device *pdev)
drivers/watchdog/at91sam9_wdt.c:static int __exit at91wdt_remove(struct platform_device *pdev)
drivers/watchdog/txx9wdt.c:static int __exit txx9wdt_remove(struct platform_device *dev)

These are mostly ancient drivers, and half of them don't even have
DT support, so I think annotating them with __refdata is probably
fine, but removing the __exit_p() and __exit annotations would
also work, depending on the individual maintainer's preferences.

There are three more drivers that set .suppress_bind_addrs=true
and have a __exit_p .remove callback (coresight-etm4x-core.c,
pcie-kirin.c, omapfb), they would also need to make the same
decision to shut up the warning.

All other drivers that have an __exit annotated .remove callback
are in probably broken and need a proper fix.

      Arnd