[PATCH v2 pciutils] lspci: Print buses of multibus PCI domain in ascending order

["Pali Rohár" <pali@kernel.org>]

Currently PCI domains are printed in ascending order. Devices on each PCI
bus are also printed in ascending order. PCI buses behind PCI-to-PCI
bridges are also printed in ascending order.

But buses of PCI domain are currently printed in descending order because
function new_bus() puts newly created bus at the beginning of linked list.

In most cases PCI domain contains only one (top level) bus, so in most
cases it is not visible this inconsistency.

Multibus PCI domains (where PCI domain contains more independent top level
PCI buses) are available on ARM devices.

This change fixes print order of multibus PCI domains, so also top level
PCI buses are printed in ascending order, like PCI buses behind PCI-to-PCI
bridges.
---
v2: Initialize bus->sibling to NULL.
---
 ls-tree.c | 11 ++++++++---
 lspci.h   |  2 +-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/ls-tree.c b/ls-tree.c
index aeb40870865e..ba7873b77649 100644
--- a/ls-tree.c
+++ b/ls-tree.c
@@ -12,7 +12,7 @@
 
 #include "lspci.h"
 
-struct bridge host_bridge = { NULL, NULL, NULL, NULL, 0, ~0, 0, ~0, NULL };
+struct bridge host_bridge = { NULL, NULL, NULL, NULL, NULL, 0, ~0, 0, ~0, NULL };
 
 static struct bus *
 find_bus(struct bridge *b, unsigned int domain, unsigned int n)
@@ -31,11 +31,15 @@ new_bus(struct bridge *b, unsigned int domain, unsigned int n)
   struct bus *bus = xmalloc(sizeof(struct bus));
   bus->domain = domain;
   bus->number = n;
-  bus->sibling = b->first_bus;
+  bus->sibling = NULL;
   bus->first_dev = NULL;
   bus->last_dev = &bus->first_dev;
   bus->parent_bridge = b;
-  b->first_bus = bus;
+  if (b->last_bus)
+    b->last_bus->sibling = bus;
+  b->last_bus = bus;
+  if (!b->first_bus)
+    b->first_bus = bus;
   return bus;
 }
 
@@ -101,6 +105,7 @@ grow_tree(void)
 	  last_br = &b->chain;
 	  b->next = b->child = NULL;
 	  b->first_bus = NULL;
+	  b->last_bus = NULL;
 	  b->br_dev = d;
 	  d->bridge = b;
 	  pacc->debug("Tree: bridge %04x:%02x:%02x.%d: %02x -> %02x-%02x\n",
diff --git a/lspci.h b/lspci.h
index fefee5256423..352177fcce7b 100644
--- a/lspci.h
+++ b/lspci.h
@@ -90,7 +90,7 @@ void show_kernel_cleanup(void);
 struct bridge {
   struct bridge *chain;			/* Single-linked list of bridges */
   struct bridge *next, *child;		/* Tree of bridges */
-  struct bus *first_bus;		/* List of buses connected to this bridge */
+  struct bus *first_bus, *last_bus;	/* List of buses connected to this bridge */
   unsigned int domain;
   unsigned int primary, secondary, subordinate;	/* Bus numbers */
   struct device *br_dev;
-- 
2.20.1