On 2015/3/12 10:55, Bjorn Helgaas wrote:
On Mon, Mar 09, 2015 at 10:34:07AM +0800, Yijing Wang wrote:
Introduce pci_host_bridge_list to manage pci host
bridges in system, so we could detect whether
the host in domain:bus is alreay registered.
Then we could remove bus alreay exist test in
__pci_create_root_bus().
It's a nice idea to move this test into the core. While you're at it, why
don't you check for any overlap with the bus ranges of existing host
bridges? For example, if we're trying to create a new host bridge to
[bus 40-7f], it should conflict with existing bridges to [bus 00-7f]
as well as to [bus 40-ff]. I think your current patch will detect the
latter conflict but not the former.
Now pci host bridge may only know its start bus number, like acpi _BBN provided,
but does not limit the end bus number, Eg. two pci roots report _BBN 0x0 and 0x80,
so we have two bus number resource (0, 0xff) and (0x80, 0xff), if we check it strictly,
some pci scan would fail which currently scan success.
Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
---
drivers/pci/host-bridge.c | 24 +++++++++++++++++++++++-
drivers/pci/probe.c | 8 +-------
include/linux/pci.h | 1 +
3 files changed, 25 insertions(+), 8 deletions(-)
diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
index 3bd45e7..0bb08ef 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(phb_mutex);
We don't use the "phb" abbreviation in the PCI core.
OK
+
static void pci_release_host_bridge_dev(struct device *dev)
{
struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
@@ -25,7 +28,7 @@ struct pci_host_bridge *pci_create_host_bridge(
int error;
int bus = PCI_BUSNUM(db);
int domain = PCI_DOMAIN(db);
- struct pci_host_bridge *host;
+ struct pci_host_bridge *host, *temp;
struct resource_entry *window, *n;
host = kzalloc(sizeof(*host), GFP_KERNEL);
@@ -40,6 +43,18 @@ struct pci_host_bridge *pci_create_host_bridge(
*/
pci_host_assign_domain_nr(host);
+ mutex_lock(&phb_mutex);
+ list_for_each_entry(temp, &pci_host_bridge_list, list)
+ if (temp->domain == host->domain
+ && temp->busnum == host->busnum) {
+ dev_dbg(&host->dev, "pci host bridge pci%04x:%02x exist\n",
+ host->domain, host->busnum);
&host->dev hasn't been initialized yet! And the text of the original
message was better.
Oh, my mistake, good catch.
+ mutex_unlock(&phb_mutex);
+ kfree(host);
+ return NULL;
+ }
+ mutex_unlock(&phb_mutex);
This is racy. Two CPUs adding a bridge to [bus 00-7f] at about the same
time can both succeed.
Hmm, I need to unlock after I add the new host bridge to the gloal host bridge list, thanks.
And it needs curly braces around the list_for_each_entry() body.
OK
+
host->dev.parent = parent;
INIT_LIST_HEAD(&host->windows);
host->dev.release = pci_release_host_bridge_dev;
@@ -55,11 +70,18 @@ struct pci_host_bridge *pci_create_host_bridge(
resource_list_for_each_entry_safe(window, n, resources)
list_move_tail(&window->node, &host->windows);
+ mutex_lock(&phb_mutex);
+ list_add_tail(&host->list, &pci_host_bridge_list);
+ mutex_unlock(&phb_mutex);
return host;
}
void pci_free_host_bridge(struct pci_host_bridge *host)
{
+ mutex_lock(&phb_mutex);
+ list_del(&host->list);
+ mutex_unlock(&phb_mutex);
+
device_unregister(&host->dev);
}
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 27ec612..7238fa3 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1870,7 +1870,7 @@ 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->ops = ops;
b->number = b->busn_res.start = bridge->busnum;
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);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 463eaa3..b621f5b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -406,6 +406,7 @@ struct pci_host_bridge {
struct device dev;
struct pci_bus *bus; /* root bus */
struct list_head windows; /* resource_entry */
+ struct list_head list;
void (*release_fn)(struct pci_host_bridge *);
void *release_data;
};
--
1.7.1
.
--
Thanks!
Yijing
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