On Thu, 2016-03-10 at 15:11 -0300, Guilherme G. Piccoli wrote:
> The domain/PHB field of PCI addresses has its value obtained from a
> global variable, incremented each time a new domain (represented by
> struct pci_controller) is added on the system. The domain addition
> process happens during boot or due to PCI device hotplug.
I'd rather we use a fixed numbering for domains, for example, under
OPAL, use the opal-id, under phyp, there is also a number in the DT we
can use (forgot what it's called) etc...
> As recent kernels are using predictable naming for network
> interfaces,
> the network stack is more tied to PCI naming. This can be a problem
> in
> hotplug scenarios, because PCI addresses will change if a device is
> removed and then re-added. This situation seems unusual, but it can
> happen if a user wants to replace a NIC without rebooting the
> machine,
> for example.
>
> This patch changes the way PCI domain values are generated: the
> global
> variable is no longer used; instead, a list is introduced, containing
> a flag that indicates whenever a domain is in use or was released,
> for
> example by a PCI hotplug remove. If the new PHB being added finds a
> free domain, it will use its number; otherwise a new number is
> generated incrementing the higher domain value present on the system.
> No functional changes were introduced.
>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxxxxxxxxxx>
> ---
> arch/powerpc/kernel/pci-common.c | 47
> +++++++++++++++++++++++++++++++++++++---
> 1 file changed, 44 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/kernel/pci-common.c
> b/arch/powerpc/kernel/pci-common.c
> index 0f7a60f..6eac0dd 100644
> --- a/arch/powerpc/kernel/pci-common.c
> +++ b/arch/powerpc/kernel/pci-common.c
> @@ -44,8 +44,12 @@
> static DEFINE_SPINLOCK(hose_spinlock);
> LIST_HEAD(hose_list);
>
> -/* XXX kill that some day ... */
> -static int global_phb_number; /* Global phb counter
> */
> +/* Global PHB counter list */
> +struct global_phb_number {
> + bool used;
> + struct list_head node;
> +};
> +LIST_HEAD(global_phb_number_list);
>
> /* ISA Memory physical address */
> resource_size_t isa_mem_base;
> @@ -64,6 +68,42 @@ struct dma_map_ops *get_pci_dma_ops(void)
> }
> EXPORT_SYMBOL(get_pci_dma_ops);
>
> +static int get_phb_number(void)
> +{
> + struct global_phb_number *ptr;
> + int latest_number = 0;
> +
> + list_for_each_entry(ptr, &global_phb_number_list, node) {
> + if (!ptr->used) {
> + ptr->used = true;
> + return latest_number;
> + }
> + latest_number++;
> + }
> +
> + ptr = zalloc_maybe_bootmem(sizeof(struct global_phb_number),
> GFP_KERNEL);
> + BUG_ON(ptr == NULL);
> +
> + ptr->used = true;
> + list_add_tail(&ptr->node, &global_phb_number_list);
> +
> + return latest_number;
> +}
> +
> +static void release_phb_number(int phb_number)
> +{
> + struct global_phb_number *ptr;
> + int current_number = 0;
> +
> + list_for_each_entry(ptr, &global_phb_number_list, node) {
> + if (current_number == phb_number) {
> + ptr->used = false;
> + return;
> + }
> + current_number++;
> + }
> +}
> +
> struct pci_controller *pcibios_alloc_controller(struct device_node
> *dev)
> {
> struct pci_controller *phb;
> @@ -72,7 +112,7 @@ struct pci_controller
> *pcibios_alloc_controller(struct device_node *dev)
> if (phb == NULL)
> return NULL;
> spin_lock(&hose_spinlock);
> - phb->global_number = global_phb_number++;
> + phb->global_number = get_phb_number();
> list_add_tail(&phb->list_node, &hose_list);
> spin_unlock(&hose_spinlock);
> phb->dn = dev;
> @@ -94,6 +134,7 @@ EXPORT_SYMBOL_GPL(pcibios_alloc_controller);
> void pcibios_free_controller(struct pci_controller *phb)
> {
> spin_lock(&hose_spinlock);
> + release_phb_number(phb->global_number);
> list_del(&phb->list_node);
> spin_unlock(&hose_spinlock);
>
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
