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Date: Tue, 10 May 2011 18:19:17 -0700
From: Yinghai Lu <yinghai@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
CC: Jesse Barnes <jbarnes@...tuousgeek.org>,
Ram Pai <linuxram@...ibm.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH -v2] pci: Check bridge resources after resource allocation.
On 05/09/2011 03:36 PM, Linus Torvalds wrote:
> On Mon, May 9, 2011 at 2:20 PM, Jesse Barnes <jbarnes@...tuousgeek.org> wrote:
>>
>> Linus? Bjorn? Ram?
>
> I dunno. The patch really makes me go "that looks *broken*". I really
> dislike it. But maybe the crappiness of the patch comes from the
> horror that is the current code.
please check if this one is ok.
[PATCH] pci: Clear bridge resource flags if requested size is 0
During pci remove/rescan testing found:
[ 541.141614] pci 0000:c0:03.0: PCI bridge to [bus c4-c9]
[ 541.141965] pci 0000:c0:03.0: bridge window [io 0x1000-0x0fff]
[ 541.159181] pci 0000:c0:03.0: bridge window [mem 0xf0000000-0xf00fffff]
[ 541.159540] pci 0000:c0:03.0: bridge window [mem 0xfc180000000-0xfc197ffffff 64bit pref]
[ 541.179374] pci 0000:c0:03.0: device not available (can't reserve [io 0x1000-0x0fff])
[ 541.199198] pci 0000:c0:03.0: Error enabling bridge (-22), continuing
[ 541.199202] pci 0000:c0:03.0: enabling bus mastering
[ 541.199209] pci 0000:c0:03.0: setting latency timer to 64
[ 541.199917] pcieport 0000:c0:03.0: device not available (can't reserve [io 0x1000-0x0fff])
[ 541.199963] pcieport: probe of 0000:c0:03.0 failed with error -22
This bug was cause by commit
| commit c8adf9a3e873eddaaec11ac410a99ef6b9656938
| Author: Ram Pai <linuxram@...ibm.com>
| Date: Mon Feb 14 17:43:20 2011 -0800
|
| PCI: pre-allocate additional resources to devices only after successful allocation of essential resources.
After that commit, pci_hotplug_io_size is changed to additional_io_size from minium size.
So it will not go through resource_size(res) != 0 path, and will not be reset there.
The root cause is: pci_bridge_check_ranges will set RESOURCE_IO flag for pci
bridge, and later if children do not need IO resource. those bridge
resources will not need to be allocated. but flags is still there. that will
confuse the the pci_enable_bridges later.
related code:
| static void assign_requested_resources_sorted(struct resource_list *head,
| struct resource_list_x *fail_head)
| {
| struct resource *res;
| struct resource_list *list;
| int idx;
|
| for (list = head->next; list; list = list->next) {
| res = list->res;
| idx = res - &list->dev->resource[0];
| if (resource_size(res) && pci_assign_resource(list->dev, idx)) {
| ...
| reset_resource(res);
| }
| }
| }
At last, We have to clear the flags in pbus_size_mem/io and etc.
also need to update adjust_resources_sorted() to handle this special case if
requested_size is 0, but add_size is not 0.
after patch, will get right result:
[ 621.206655] pci 0000:c0:03.0: PCI bridge to [bus c4-c9]
[ 621.206912] pci 0000:c0:03.0: bridge window [io disabled]
[ 621.226594] pci 0000:c0:03.0: bridge window [mem 0xf0000000-0xf00fffff]
[ 621.226904] pci 0000:c0:03.0: bridge window [mem 0xfc180000000-0xfc197ffffff 64bit pref]
[ 621.247012] pci 0000:c0:03.0: enabling bus mastering
[ 621.247275] pci 0000:c0:03.0: setting latency timer to 64
[ 621.267656] pcieport 0000:c0:03.0: setting latency timer to 64
[ 621.268134] pcieport 0000:c0:03.0: irq 160 for MSI/MSI-X
[ 621.286832] pcieport 0000:c0:03.0: Signaling PME through PCIe PME interrupt
[ 621.306360] pci 0000:c4:00.0: Signaling PME through PCIe PME interrupt
[ 621.306684] pcie_pme 0000:c0:03.0:pcie01: service driver pcie_pme loaded
[ 621.326512] aer 0000:c0:03.0:pcie02: service driver aer loaded
[ 621.326911] pciehp 0000:c0:03.0:pcie04: Hotplug Controller:
Signed-off-by: Yinghai Lu <yinghai@...nel.org>
---
drivers/pci/setup-bus.c | 31 +++++++++++++++++++++----------
1 file changed, 21 insertions(+), 10 deletions(-)
Index: linux-2.6/drivers/pci/setup-bus.c
===================================================================
--- linux-2.6.orig/drivers/pci/setup-bus.c
+++ linux-2.6/drivers/pci/setup-bus.c
@@ -138,9 +138,26 @@ static void adjust_resources_sorted(stru
for (list = add_head->next; list;) {
res = list->res;
/* skip resource that has been reset */
- if (!res->flags)
+ if (!res->flags && !res->start && !res->end)
goto out;
+ idx = res - &list->dev->resource[0];
+ add_size = list->add_size;
+ if (!add_size) {
+ dev_warn(&list->dev->dev, "idx %d add_size == 0\n",
+ idx);
+ goto out;
+ }
+
+ if (!resource_size(res)) {
+ /* need to restore the flag */
+ res->flags = list->flags;
+ res->end = res->start + add_size - 1;
+ if (pci_assign_resource(list->dev, idx))
+ reset_resource(res);
+ goto out;
+ }
+
/* skip this resource if not found in head list */
for (hlist = head->next; hlist && hlist->res != res;
hlist = hlist->next);
@@ -150,16 +167,8 @@ static void adjust_resources_sorted(stru
continue;
}
- idx = res - &list->dev->resource[0];
- add_size=list->add_size;
- if (!resource_size(res) && add_size) {
- res->end = res->start + add_size - 1;
- if(pci_assign_resource(list->dev, idx))
- reset_resource(res);
- } else if (add_size) {
- adjust_resource(res, res->start,
+ adjust_resource(res, res->start,
resource_size(res) + add_size);
- }
out:
tmp = list;
prev->next = list = list->next;
@@ -596,6 +605,8 @@ static void pbus_size_io(struct pci_bus
b_res->flags |= IORESOURCE_STARTALIGN;
if (size1 > size0 && add_head)
add_to_list(add_head, bus->self, b_res, size1-size0);
+ if (!size0)
+ b_res->flags = 0;
}
/**
@@ -693,6 +704,8 @@ static int pbus_size_mem(struct pci_bus
b_res->flags |= IORESOURCE_STARTALIGN | mem64_mask;
if (size1 > size0 && add_head)
add_to_list(add_head, bus->self, b_res, size1-size0);
+ if (!size0)
+ b_res->flags = 0;
return 1;
}
--
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