Re: [PATCH v8 10/30] PCI: Introduce pci_host_bridge_list to manage host bridges

[Tomasz Nowicki <tomasz.nowicki@linaro.org>]

On 24.03.2015 04:34, Yijing Wang wrote:
> Introduce pci_host_bridge_list to manage pci host
> bridges in system, this make us have the ability
> to check whether the new host would conflict with
> existing one. Then we could remove bus alreay exist
> check in __pci_create_root_bus().
>
> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
> ---
>   drivers/pci/host-bridge.c |   41 ++++++++++++++++++++++++++++++++++++++++-
>   drivers/pci/probe.c       |    9 +--------
>   include/linux/pci.h       |    1 +
>   3 files changed, 42 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
> index 1a9834b..8af6d51 100644
> --- a/drivers/pci/host-bridge.c
> +++ b/drivers/pci/host-bridge.c
> @@ -8,6 +8,9 @@
>
>   #include "pci.h"
>
> +static LIST_HEAD(pci_host_bridge_list);
> +static DEFINE_MUTEX(pci_host_mutex);
> +
>   static void pci_release_host_bridge_dev(struct device *dev)
>   {
>   	struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
> @@ -41,12 +44,29 @@ static void pci_host_update_busn_res(
>   	pci_add_resource(resources, &host->busn_res);
>   }
>
> +static bool pci_host_busn_res_overlap(
> +		struct pci_host_bridge *new, struct pci_host_bridge *old)
> +{
> +	struct resource_entry *entry;
> +	struct resource *res1 = NULL, *res2 = NULL;
> +
> +	resource_list_for_each_entry(entry, &old->windows)
> +		if (entry->res->flags & IORESOURCE_BUS)
> +			res1 = entry->res;
> +
> +	resource_list_for_each_entry(entry, &new->windows)
> +		if (entry->res->flags & IORESOURCE_BUS)
> +			res2 = entry->res;
> +
> +	return resource_overlaps(res1, res2);
> +}
> +
>   struct pci_host_bridge *pci_create_host_bridge(
>   		struct device *parent, int domain, int bus,
>   		struct list_head *resources)
>   {
>   	int error;
> -	struct pci_host_bridge *host;
> +	struct pci_host_bridge *host, *tmp;
>   	struct resource_entry *window, *n;
>
>   	host = kzalloc(sizeof(*host), GFP_KERNEL);
> @@ -65,6 +85,21 @@ struct pci_host_bridge *pci_create_host_bridge(
>   	 */
>   	host->domain = domain;
>   	pci_host_assign_domain_nr(host);
> +	mutex_lock(&pci_host_mutex);
> +	list_for_each_entry(tmp, &pci_host_bridge_list, list) {
> +		if (tmp->domain != host->domain
> +			  || pci_host_busn_res_overlap(host, tmp)) {

I think you should construct condition this way:
+		if (tmp->domain == host->domain
+			  && pci_host_busn_res_overlap(host, tmp)) {

Regards,
Tomasz

> +			pr_warn("pci host bridge pci%04x:%02x exist\n",
> +					host->domain, bus);
> +			mutex_unlock(&pci_host_mutex);
> +			pci_free_resource_list(&host->windows);
> +			kfree(host);
> +			return NULL;
> +		}
> +	}
> +	list_add_tail(&host->list, &pci_host_bridge_list);
> +	mutex_unlock(&pci_host_mutex);
> +
>   	host->dev.release = pci_release_host_bridge_dev;
>   	dev_set_name(&host->dev, "pci%04x:%02x",
>   			host->domain, bus);
> @@ -80,6 +115,10 @@ struct pci_host_bridge *pci_create_host_bridge(
>
>   void pci_free_host_bridge(struct pci_host_bridge *host)
>   {
> +	mutex_lock(&pci_host_mutex);
> +	list_del(&host->list);
> +	mutex_unlock(&pci_host_mutex);
> +
>   	device_unregister(&host->dev);
>   }
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 25ac741..8517d1b 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1869,7 +1869,7 @@ static struct pci_bus *__pci_create_root_bus(
>   		void *sysdata)
>   {
>   	int error;
> -	struct pci_bus *b, *b2;
> +	struct pci_bus *b;
>   	struct resource_entry *window;
>   	struct device *parent;
>   	struct resource *res;
> @@ -1887,12 +1887,6 @@ static struct pci_bus *__pci_create_root_bus(
>   	b->number = b->busn_res.start =
>   		pci_host_first_busnr(bridge);
>   	pci_bus_assign_domain_nr(b, parent);
> -	b2 = pci_find_bus(pci_domain_nr(b), b->number);
> -	if (b2) {
> -		/* If we already got to this bus through a different bridge, ignore it */
> -		dev_dbg(&b2->dev, "bus already known\n");
> -		goto err_out;
> -	}
>
>   	bridge->bus = b;
>   	b->bridge = get_device(&bridge->dev);
> @@ -1952,7 +1946,6 @@ static struct pci_bus *__pci_create_root_bus(
>
>   put_dev:
>   	put_device(&bridge->dev);
> -err_out:
>   	kfree(b);
>   	return NULL;
>   }
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index f189dfb..91cba01 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -407,6 +407,7 @@ struct pci_host_bridge {
>   	/* we use default bus resource if no bus resource provided */
>   	struct resource busn_res;
>   	struct list_head windows;	/* resource_entry */
> +	struct list_head list;
>   	void (*release_fn)(struct pci_host_bridge *);
>   	void *release_data;
>   };
>