Messages in this thread |  | | Date | Wed, 6 Feb 2013 11:07:07 +0900 | From | Joonsoo Kim <> | Subject | Re: [PATCH v5 3/3] ARM: mm: use static_vm for managing static mapped areas |
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Hello, Rob.
On Tue, Feb 05, 2013 at 01:12:51PM -0600, Rob Herring wrote: > On 02/05/2013 12:13 PM, Nicolas Pitre wrote: > > On Tue, 5 Feb 2013, Rob Herring wrote: > > > >> On 02/04/2013 10:44 PM, Nicolas Pitre wrote: > >>> On Tue, 5 Feb 2013, Joonsoo Kim wrote: > >>> > >>>> A static mapped area is ARM-specific, so it is better not to use > >>>> generic vmalloc data structure, that is, vmlist and vmlist_lock > >>>> for managing static mapped area. And it causes some needless overhead and > >>>> reducing this overhead is better idea. > >>>> > >>>> Now, we have newly introduced static_vm infrastructure. > >>>> With it, we don't need to iterate all mapped areas. Instead, we just > >>>> iterate static mapped areas. It helps to reduce an overhead of finding > >>>> matched area. And architecture dependency on vmalloc layer is removed, > >>>> so it will help to maintainability for vmalloc layer. > >>>> > >>>> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> > >> > >> [snip] > >> > >>>> @@ -859,17 +864,12 @@ static void __init pci_reserve_io(void) > >>>> { > >>>> struct vm_struct *vm; > >>>> unsigned long addr; > >>>> + struct static_vm *svm; > >>>> > >>>> - /* we're still single threaded hence no lock needed here */ > >>>> - for (vm = vmlist; vm; vm = vm->next) { > >>>> - if (!(vm->flags & VM_ARM_STATIC_MAPPING)) > >>>> - continue; > >>>> - addr = (unsigned long)vm->addr; > >>>> - addr &= ~(SZ_2M - 1); > >>>> - if (addr == PCI_IO_VIRT_BASE) > >>>> - return; > >>>> + svm = find_static_vm_vaddr((void *)PCI_IO_VIRT_BASE); > >>>> + if (svm) > >>>> + return; > >>>> > >>>> - } > >>>> > >>>> vm_reserve_area_early(PCI_IO_VIRT_BASE, SZ_2M, pci_reserve_io); > >>>> } > >>> > >>> The replacement code is not equivalent. I can't recall why the original > >>> is as it is, but it doesn't look right to me. The 2MB round down > >>> certainly looks suspicious. > >> > >> The PCI mapping is at a fixed, aligned 2MB mapping. If we find any > >> virtual address within that region already mapped, it is an error. > > Ah, OK. This wasn't clear looking at the code. > >> We probably should have had a WARN here. > > > > Indeed. > >
Okay. I should fix it to find any mapping within PCI reserved region. But, I think that it is not an error. Now, I see your original commit 'c2794437091a4fda72c4a4f3567dd728dcc0c3c9' and find below message.
"Platforms which need early i/o mapping (e.g. for vga console) can call pci_map_io_early in their .map_io function."
Therfore, for some platform, it is possible that there is a mapping within PCI reserved range.
So, I will not add WARN here.
I will fix and re-send v6 with your ACK.
Thanks for review.
> >>> > >>> The replacement code should be better. However I'd like you to get an > >>> ACK from Rob Herring as well for this patch. > >> > >> It doesn't appear to me the above case is handled. The virt addr is > >> checked whether it is within an existing mapping, but not whether the > >> new mapping would overlap an existing mapping. It would be good to check > >> for this generically rather than specifically for the PCI i/o mapping. > > > > Agreed. However that is checked already in vm_area_add_early(). > > Therefore the overlap test here is redundant. > > Ah, right. In that case: > > Acked-by: Rob Herring <rob.herring@calxeda.com> > > Rob > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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