[PATCH v8 21/61] PCI: Treat optional as required in first try for bridge rescan

From: Yinghai Lu
Date: Tue Oct 27 2015 - 17:15:02 EST

For rescan bridge/bus that children are removed before, we should treat
optional as required just like root bus the boot time in 19aa7ee432ce
(PCI: make re-allocation try harder by reassigning ranges higher in
the heirarchy).

The reason: allocate required and expand to optional path do not
put failed resource to fail list, so will lose required info before
next try.

So we are using following way:
1. First and following try before last try:
We don't keep realloc list so treat every optional as required.
allocate for required+optional and put failed in the fail list.
then size info (include must and optonal separatedly) will be kept
for next try.
2. last try:
a: try to allocate required+optional to see if all get allocated.
b: try to allocate required then expand to optional.

Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
drivers/pci/setup-bus.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 53ab81f..5505942 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1802,25 +1802,34 @@ void __init pci_assign_unassigned_resources(void)
void pci_assign_unassigned_bridge_resources(struct pci_dev *bridge)
struct pci_bus *parent = bridge->subordinate;
- LIST_HEAD(add_list); /* list of resources that
+ LIST_HEAD(realloc_head); /* list of resources that
want additional resources */
+ struct list_head *add_list = NULL;
int tried_times = 0;
struct pci_dev_resource *fail_res;
int retval;
unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM |
+ int pci_try_num = 2;

- __pci_bus_size_bridges(parent, &add_list);
- __pci_bridge_assign_resources(bridge, &add_list, &fail_head);
- pci_bus_check_realloc(&add_list);
+ /*
+ * last try will use add_list, otherwise will try good to have as
+ * must have, so can realloc parent bridge resource
+ */
+ if (tried_times + 1 == pci_try_num)
+ add_list = &realloc_head;
+ __pci_bus_size_bridges(parent, add_list);
+ __pci_bridge_assign_resources(bridge, add_list, &fail_head);
+ if (add_list)
+ pci_bus_check_realloc(add_list);

if (list_empty(&fail_head))
goto enable_all;

- if (tried_times >= 2) {
+ if (tried_times >= pci_try_num) {
/* still fail, don't need to try more */
goto enable_all;

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