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[v11,2/7] PCI: A fix for caculating bridge window's size and alignment

Message ID 20170417213639.21092.22951.stgit@bhelgaas-glaptop.roam.corp.google.com (mailing list archive)
State New, archived
Delegated to: Bjorn Helgaas
Headers show

Commit Message

Bjorn Helgaas April 17, 2017, 9:36 p.m. UTC 
From: Yongji Xie <elohimes@gmail.com>

In case that one device's alignment is greater than its size,
we may get an incorrect size and alignment for its bus's memory
window in pbus_size_mem(). This patch fixes this case.

Signed-off-by: Yongji Xie <elohimes@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/setup-bus.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Yinghai Lu April 17, 2017, 9:45 p.m. UTC | #1 
On Mon, Apr 17, 2017 at 2:36 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
> From: Yongji Xie <elohimes@gmail.com>
>
> In case that one device's alignment is greater than its size,
> we may get an incorrect size and alignment for its bus's memory
> window in pbus_size_mem(). This patch fixes this case.

In which case, that device alignment is not same as size?
or powerpc need small size, but alignment is PAGE_SIZE?

Thanks

Yinghai
Yongji Xie April 18, 2017, 2:16 a.m. UTC | #2 
Hi Yinghai,

On 18 April 2017 at 05:45, Yinghai Lu <yinghai@kernel.org> wrote:
> On Mon, Apr 17, 2017 at 2:36 PM, Bjorn Helgaas <bhelgaas@google.com> wrote:
>> From: Yongji Xie <elohimes@gmail.com>
>>
>> In case that one device's alignment is greater than its size,
>> we may get an incorrect size and alignment for its bus's memory
>> window in pbus_size_mem(). This patch fixes this case.
>
> In which case, that device alignment is not same as size?
> or powerpc need small size, but alignment is PAGE_SIZE?
>

Yes, powerpc may have some small size (smaller than PAGE_SIZE)
devices whose alignment would be enforced to be PAGE_SIZE
by pcibios_default_alignment() (in patch 4).

Thanks,
Yongji
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Patch

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index cb389277df41..958da7db9033 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1066,10 +1066,10 @@  static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
 				r->flags = 0;
 				continue;
 			}
-			size += r_size;
+			size += max(r_size, align);
 			/* Exclude ranges with size > align from
 			   calculation of the alignment. */
-			if (r_size == align)
+			if (r_size <= align)
 				aligns[order] += align;
 			if (order > max_order)
 				max_order = order;