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

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.
---
 ls-tree.c | 10 +++++++---
 lspci.h   |  2 +-
 2 files changed, 8 insertions(+), 4 deletions(-)

On Monday 20 December 2021 20:53:49 Pali Rohár wrote:
> 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.
> ---
>  ls-tree.c | 10 +++++++---
>  lspci.h   |  2 +-
>  2 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/ls-tree.c b/ls-tree.c
> index aeb40870865e..17a95307b3fa 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 +31,14 @@ 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;

Oops, this is a mistake. Default value for bus->sibling needs to be
explicitly set because xmalloc() wrapper does not return zero
initialized memory. So correct change for above line should be:

-  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 +104,7 @@ 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
>

Hi!

> Oops, this is a mistake. Default value for bus->sibling needs to be
> explicitly set because xmalloc() wrapper does not return zero
> initialized memory. So correct change for above line should be:

Fine, could you please re-submit the whole patch.

					Martin