Re: [patch 06/17] scsi: fix section mismatch in aic94xx

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Fri, 2008-03-28 at 14:48 -0700, akpm@linux-foundation.org wrote:
> From: Sam Ravnborg <sam@ravnborg.org>
> 
> Fix following warnings:
> WARNING: vmlinux.o(.data+0x17aa88): Section mismatch in reference from the variable asd_pcidev_data to the function .devinit.text:asd_aic9410_setup()
> WARNING: vmlinux.o(.data+0x17aa98): Section mismatch in reference from the variable asd_pcidev_data to the function .devinit.text:asd_aic9410_setup()
> WARNING: vmlinux.o(.data+0x17aaa8): Section mismatch in reference from the variable asd_pcidev_data to the function .devinit.text:asd_aic9405_setup()
> 
> asd_pcidev_data is only used by __devinit asd_pci_probe.  So mark is const and
> annotate it __devinitconst to fix the warnings.
> 
> [akpm@linux-foundation.org: fix warning]
> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
> Cc: Gilbert Wu <gilbert_wu@adaptec.com>
> Cc: James Bottomley <James.Bottomley@SteelEye.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
>  drivers/scsi/aic94xx/aic94xx_init.c |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff -puN drivers/scsi/aic94xx/aic94xx_init.c~scsi-fix-section-mismatch-in-aic94xx drivers/scsi/aic94xx/aic94xx_init.c
> --- a/drivers/scsi/aic94xx/aic94xx_init.c~scsi-fix-section-mismatch-in-aic94xx
> +++ a/drivers/scsi/aic94xx/aic94xx_init.c
> @@ -529,10 +529,10 @@ static void asd_remove_dev_attrs(struct 
>  /* The first entry, 0, is used for dynamic ids, the rest for devices
>   * we know about.
>   */
> -static struct asd_pcidev_struct {
> +static const struct asd_pcidev_struct {
>  	const char * name;
>  	int (*setup)(struct asd_ha_struct *asd_ha);
> -} asd_pcidev_data[] = {
> +} asd_pcidev_data[] __devinitconst = {
>  	/* Id 0 is used for dynamic ids. */
>  	{ .name  = "Adaptec AIC-94xx SAS/SATA Host Adapter",
>  	  .setup = asd_aic9410_setup

If your tools say this patch is correct, then the tools are wrong.

This patch actually takes something that's functionally correct but your
tools can't see it and transforms it to something that's actually
functionally wrong ... and the tool should spot that.

the problem is the contents of the .name field ... they can't live in
the devinit rodata section because we actually take a pointer to it (as
asd_ha->name and later ha->sas_ha_name) in asd_pci_probe() that lives
the entire lifetime of the driver and is used.  derefing it will trigger
a bug after the __devinit section is discarded in the non hotplug case.

James