[PATCH] remove __ioremap_explicit() error message

[John Rose]

Ack, why can't I ever remember:

Signed-off-by: John Rose <johnrose at austin.ibm.com>


On Wed, 2004-09-29 at 14:30, John Rose wrote:
> Here's a really long explanation for a really short patch! :)
> 
> As an unfortunate side effect of runtime addition/removal of PCI Host Bridges,
> the RPA DLPAR driver can no longer depend on the success of ioremap_explicit() 
> (and therefore remap_page_range()) for the case of DLPAR adding an I/O Slot.  
> 
> Without addressing this, an attempt to add the first child slot of a newly
> added PHB will fail when __ioremap_explicit() determines the mappings for that
> range to already exist.
> 
> For a little context, __ioremap_explicit() creates mappings for the range of a
> newly added slot.  Here's why these calls will be expected to fail in some
> cases.  Keep in mind that at boot-time, the PPC64 kernel calls ioremap() for
> the entire range spanned by each PHB.  Consider the following scenarios of
> DLPAR-adding an I/O slot.
> 
> 1) Just after boot, one removes an I/O slot.  At this point the range 
>    associated with the parent PHB is fragmented, and the child range for the 
>    slot in question is iounmap()'ed.  One then re-adds the slot, at which point
>    remap_page_range()/ioremap_explicit() restores the mappings that were 
>    previously removed.
> 
> 2) One adds a new PHB, at which point the ppc64-specific addition ioremaps the 
>    entire PHB range.  One then performs a DLPAR-add of a child slot of that
>    PHB.  At this point, mappings already exist for the range of the slot to
>    be added.  So remap_page_range()/ioremap_explicit() will fail at this point.
> 
> The problem is, there's not a good way to distinguish between cases 1 and 2
> from the perspective of the DLPAR driver.  Because of that, I believe the
> correct solution to be:
> 
> - Removal of relevant error prints from iounmap_explicit(), which is only used 
>   for DLPAR.
> - Removal of error code checks from the RPA driver
> 
> Here's the first of these.
> 
> Thanks-
> John
> 
> diff -Nru a/arch/ppc64/mm/init.c b/arch/ppc64/mm/init.c
> --- a/arch/ppc64/mm/init.c	Wed Sep 29 14:10:06 2004
> +++ b/arch/ppc64/mm/init.c	Wed Sep 29 14:10:06 2004
> @@ -265,7 +265,7 @@
>  	} else {
>  		area = im_get_area(ea, size, IM_REGION_UNUSED|IM_REGION_SUBSET);
>  		if (area == NULL) {
> -			printk(KERN_ERR "could not obtain imalloc area for ea 0x%lx\n", ea);
> +			/* Expected when PHB-dlpar is in play */
>  			return 1;
>  		}
>  		if (ea != (unsigned long) area->addr) {