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

[Sam Ravnborg <sam@ravnborg.org>]

On Sun, Mar 30, 2008 at 01:05:04PM -0500, James Bottomley wrote:
> 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.
asd_pcidev_dada[].name is dereferenced only in the above mentioned function.
The string is used in other places - correct. But this patch does
not try to move the defined string anywhere only the data member
holding the pointer to the string.

Take a look at the content of .rodata.str1.1 to see the string
being contained there.

	Sam