This is v2 of a patch series that:
a) exports struct acpi_pci_root
b) fixes an assumption in acpiphp about finding struct pci_bus
It's a minimal fix that's aimed at -rc4, as (b) fixes an assumption
introduced in -rc1.
I'll send the rest of the cleanups for linux-next later, after doing
some more testing.
Original thread here:
http://thread.gmane.org/gmane.linux.kernel.pci/5080
v1 -> v2:
- fixed build error in acpi_pci_root
- reduced patch series in scope to be much smaller
---
Alex Chiang (2):
ACPI: export acpi_pci_root and friends
PCI Hotplug: acpiphp: get pci_bus from acpi handle correctly
drivers/acpi/pci_root.c | 17 ++---------------
drivers/pci/hotplug/acpiphp_glue.c | 27 ++++++++++++++++-----------
include/acpi/acpi_bus.h | 16 ++++++++++++++++
3 files changed, 34 insertions(+), 26 deletions(-)
We can simplify ACPI drivers if we can tell whether a handle is an
ACPI PCI root or not.
Cc: Bjorn Helgaas <[email protected]>
Signed-off-by: Alex Chiang <[email protected]>
---
drivers/acpi/pci_root.c | 17 ++---------------
include/acpi/acpi_bus.h | 16 ++++++++++++++++
2 files changed, 18 insertions(+), 15 deletions(-)
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 55b5b90..31b961c 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -61,20 +61,6 @@ static struct acpi_driver acpi_pci_root_driver = {
},
};
-struct acpi_pci_root {
- struct list_head node;
- struct acpi_device *device;
- struct pci_bus *bus;
- u16 segment;
- u8 bus_nr;
-
- u32 osc_support_set; /* _OSC state of support bits */
- u32 osc_control_set; /* _OSC state of control bits */
- u32 osc_control_qry; /* the latest _OSC query result */
-
- u32 osc_queried:1; /* has _OSC control been queried? */
-};
-
static LIST_HEAD(acpi_pci_roots);
static struct acpi_pci_driver *sub_driver;
@@ -317,7 +303,7 @@ static acpi_status acpi_pci_osc_support(struct acpi_pci_root *root, u32 flags)
return status;
}
-static struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle)
+struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle)
{
struct acpi_pci_root *root;
@@ -327,6 +313,7 @@ static struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle)
}
return NULL;
}
+EXPORT_SYMBOL_GPL(acpi_pci_find_root);
struct acpi_handle_node {
struct list_head node;
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index c65e4ce..c3ace75 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -369,10 +369,26 @@ int register_acpi_bus_type(struct acpi_bus_type *);
int unregister_acpi_bus_type(struct acpi_bus_type *);
struct device *acpi_get_physical_device(acpi_handle);
+struct acpi_pci_root {
+ struct list_head node;
+ struct acpi_device * device;
+ struct acpi_pci_id id;
+ struct pci_bus *bus;
+ u16 segment;
+ u8 bus_nr;
+
+ u32 osc_support_set; /* _OSC state of support bits */
+ u32 osc_control_set; /* _OSC state of control bits */
+ u32 osc_control_qry; /* the latest _OSC query result */
+
+ u32 osc_queried:1; /* has _OSC control been queried? */
+};
+
/* helper */
acpi_handle acpi_get_child(acpi_handle, acpi_integer);
int acpi_is_root_bridge(acpi_handle);
acpi_handle acpi_get_pci_rootbridge_handle(unsigned int, unsigned int);
+struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle);
#define DEVICE_ACPI_HANDLE(dev) ((acpi_handle)((dev)->archdata.acpi_handle))
#ifdef CONFIG_PM_SLEEP
We cannot simply call acpi_get_pci_dev() on any random ACPI handle
and hope that it works, because a PCI root bridge may not have
an associated struct pci_dev.
This is allowed per the PCI specification, and is referred to as a
non-materialized bridge.
So, depending on the type of PCI bridge that the handle points to,
use the appropriate interface to return the struct pci_bus correctly.
Signed-off-by: Alex Chiang <[email protected]>
---
drivers/pci/hotplug/acpiphp_glue.c | 27 ++++++++++++++++-----------
1 files changed, 16 insertions(+), 11 deletions(-)
diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 0cb0f83..fa4658b 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -62,6 +62,21 @@ static void acpiphp_sanitize_bus(struct pci_bus *bus);
static void acpiphp_set_hpp_values(acpi_handle handle, struct pci_bus *bus);
static void handle_hotplug_event_func(acpi_handle handle, u32 type, void *context);
+static struct pci_bus *pci_bus_from_handle(acpi_handle handle)
+{
+ struct pci_bus *pbus;
+
+ if (acpi_is_root_bridge(handle)) {
+ struct acpi_pci_root *root = acpi_pci_find_root(handle);
+ pbus = root->bus;
+ } else {
+ struct pci_dev *pdev = acpi_get_pci_dev(handle);
+ pbus = pdev->subordinate;
+ pci_dev_put(pdev);
+ }
+ return pbus;
+}
+
/* callback routine to check for the existence of a pci dock device */
static acpi_status
is_pci_dock_device(acpi_handle handle, u32 lvl, void *context, void **rv)
@@ -1387,16 +1402,7 @@ static void acpiphp_sanitize_bus(struct pci_bus *bus)
/* Program resources in newly inserted bridge */
static int acpiphp_configure_bridge (acpi_handle handle)
{
- struct pci_dev *dev;
- struct pci_bus *bus;
-
- dev = acpi_get_pci_dev(handle);
- if (!dev) {
- err("cannot get PCI domain and bus number for bridge\n");
- return -EINVAL;
- }
-
- bus = dev->bus;
+ struct pci_bus *bus = pci_bus_from_handle(handle);
pci_bus_size_bridges(bus);
pci_bus_assign_resources(bus);
@@ -1404,7 +1410,6 @@ static int acpiphp_configure_bridge (acpi_handle handle)
acpiphp_set_hpp_values(handle, bus);
pci_enable_bridges(bus);
acpiphp_configure_ioapics(handle);
- pci_dev_put(dev);
return 0;
}
On Tuesday 14 July 2009 02:53:33 pm Alex Chiang wrote:
> We cannot simply call acpi_get_pci_dev() on any random ACPI handle
> and hope that it works, because a PCI root bridge may not have
> an associated struct pci_dev.
>
> This is allowed per the PCI specification, and is referred to as a
> non-materialized bridge.
>
> So, depending on the type of PCI bridge that the handle points to,
> use the appropriate interface to return the struct pci_bus correctly.
>
> Signed-off-by: Alex Chiang <[email protected]>
> ---
>
> drivers/pci/hotplug/acpiphp_glue.c | 27 ++++++++++++++++-----------
> 1 files changed, 16 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index 0cb0f83..fa4658b 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -62,6 +62,21 @@ static void acpiphp_sanitize_bus(struct pci_bus *bus);
> static void acpiphp_set_hpp_values(acpi_handle handle, struct pci_bus *bus);
> static void handle_hotplug_event_func(acpi_handle handle, u32 type, void *context);
>
> +static struct pci_bus *pci_bus_from_handle(acpi_handle handle)
> +{
> + struct pci_bus *pbus;
> +
> + if (acpi_is_root_bridge(handle)) {
> + struct acpi_pci_root *root = acpi_pci_find_root(handle);
> + pbus = root->bus;
> + } else {
> + struct pci_dev *pdev = acpi_get_pci_dev(handle);
> + pbus = pdev->subordinate;
> + pci_dev_put(pdev);
> + }
> + return pbus;
I worry that acpi_is_root_bridge() merely checks the device IDs of
"handle", which isn't quite the same as checking whether the pci_root
driver has claimed "handle".
Are you confident that it's safe to move the pci_dev_put(), so it is
released before configuring the bridge?
What do you think about something like this (even though the get/put
is still a little clunky):
struct pci_dev *dev = NULL;
root = acpi_pci_find_root(handle);
if (root)
bus = root->bus;
else {
dev = acpi_get_pci_dev(handle);
if (dev)
bus = pdev->subordinate;
else {
err("cannot get PCI domain and bus number for bridge\n");
return -EINVAL;
}
}
pci_bus_size_bridges(bus);
...
if (dev)
pci_dev_put(dev);
return 0;
> +}
> +
> /* callback routine to check for the existence of a pci dock device */
> static acpi_status
> is_pci_dock_device(acpi_handle handle, u32 lvl, void *context, void **rv)
> @@ -1387,16 +1402,7 @@ static void acpiphp_sanitize_bus(struct pci_bus *bus)
> /* Program resources in newly inserted bridge */
> static int acpiphp_configure_bridge (acpi_handle handle)
> {
> - struct pci_dev *dev;
> - struct pci_bus *bus;
> -
> - dev = acpi_get_pci_dev(handle);
> - if (!dev) {
> - err("cannot get PCI domain and bus number for bridge\n");
> - return -EINVAL;
> - }
> -
> - bus = dev->bus;
> + struct pci_bus *bus = pci_bus_from_handle(handle);
>
> pci_bus_size_bridges(bus);
> pci_bus_assign_resources(bus);
> @@ -1404,7 +1410,6 @@ static int acpiphp_configure_bridge (acpi_handle handle)
> acpiphp_set_hpp_values(handle, bus);
> pci_enable_bridges(bus);
> acpiphp_configure_ioapics(handle);
> - pci_dev_put(dev);
> return 0;
> }
* Bjorn Helgaas <[email protected]>:
> On Tuesday 14 July 2009 02:53:33 pm Alex Chiang wrote:
> > We cannot simply call acpi_get_pci_dev() on any random ACPI handle
> > and hope that it works, because a PCI root bridge may not have
> > an associated struct pci_dev.
> >
> > This is allowed per the PCI specification, and is referred to as a
> > non-materialized bridge.
> >
> > So, depending on the type of PCI bridge that the handle points to,
> > use the appropriate interface to return the struct pci_bus correctly.
> >
> > Signed-off-by: Alex Chiang <[email protected]>
> > ---
> >
> > drivers/pci/hotplug/acpiphp_glue.c | 27 ++++++++++++++++-----------
> > 1 files changed, 16 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> > index 0cb0f83..fa4658b 100644
> > --- a/drivers/pci/hotplug/acpiphp_glue.c
> > +++ b/drivers/pci/hotplug/acpiphp_glue.c
> > @@ -62,6 +62,21 @@ static void acpiphp_sanitize_bus(struct pci_bus *bus);
> > static void acpiphp_set_hpp_values(acpi_handle handle, struct pci_bus *bus);
> > static void handle_hotplug_event_func(acpi_handle handle, u32 type, void *context);
> >
> > +static struct pci_bus *pci_bus_from_handle(acpi_handle handle)
> > +{
> > + struct pci_bus *pbus;
> > +
> > + if (acpi_is_root_bridge(handle)) {
> > + struct acpi_pci_root *root = acpi_pci_find_root(handle);
> > + pbus = root->bus;
> > + } else {
> > + struct pci_dev *pdev = acpi_get_pci_dev(handle);
> > + pbus = pdev->subordinate;
> > + pci_dev_put(pdev);
> > + }
> > + return pbus;
>
> I worry that acpi_is_root_bridge() merely checks the device IDs of
> "handle", which isn't quite the same as checking whether the pci_root
> driver has claimed "handle".
Hm, I understand this concern in a theoretical sense, but could
you explain more of what you're thinking about, and give me a
concrete example of something that might go wrong here?
> Are you confident that it's safe to move the pci_dev_put(), so it is
> released before configuring the bridge?
I'm confident that I'm not changing the lifetime assumptions in
acpiphp_configure_bridge(), as the old code didn't seem to care
either.
Commit d6aa484c (acpiphp: convert to acpi_get_pci_dev) changed
from pci_find_bus() to use acpi_get_pci_dev(), and pci_find_bus()
does not elevate any reference counts.
What I'm trying to fix here is that acpi_get_pci_dev() /might/
not work all the time, namely on machines that have both:
a) hotpluggable root bridges
b) non-materialized root bridges
> What do you think about something like this (even though the get/put
> is still a little clunky):
>
> struct pci_dev *dev = NULL;
>
> root = acpi_pci_find_root(handle);
> if (root)
> bus = root->bus;
> else {
> dev = acpi_get_pci_dev(handle);
> if (dev)
> bus = pdev->subordinate;
> else {
> err("cannot get PCI domain and bus number for bridge\n");
> return -EINVAL;
> }
> }
>
> pci_bus_size_bridges(bus);
> ...
> if (dev)
> pci_dev_put(dev);
> return 0;
This seems like a good approach too, but I'd like to understand
your concern about acpi_is_root_bridge() first.
Thanks for the review.
/ac
On Tuesday 21 July 2009 01:57:55 pm Alex Chiang wrote:
> * Bjorn Helgaas <[email protected]>:
> > On Tuesday 14 July 2009 02:53:33 pm Alex Chiang wrote:
> > > We cannot simply call acpi_get_pci_dev() on any random ACPI handle
> > > and hope that it works, because a PCI root bridge may not have
> > > an associated struct pci_dev.
> > >
> > > This is allowed per the PCI specification, and is referred to as a
> > > non-materialized bridge.
> > >
> > > So, depending on the type of PCI bridge that the handle points to,
> > > use the appropriate interface to return the struct pci_bus correctly.
> > >
> > > Signed-off-by: Alex Chiang <[email protected]>
> > > ---
> > >
> > > drivers/pci/hotplug/acpiphp_glue.c | 27 ++++++++++++++++-----------
> > > 1 files changed, 16 insertions(+), 11 deletions(-)
> > >
> > > diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> > > index 0cb0f83..fa4658b 100644
> > > --- a/drivers/pci/hotplug/acpiphp_glue.c
> > > +++ b/drivers/pci/hotplug/acpiphp_glue.c
> > > @@ -62,6 +62,21 @@ static void acpiphp_sanitize_bus(struct pci_bus *bus);
> > > static void acpiphp_set_hpp_values(acpi_handle handle, struct pci_bus *bus);
> > > static void handle_hotplug_event_func(acpi_handle handle, u32 type, void *context);
> > >
> > > +static struct pci_bus *pci_bus_from_handle(acpi_handle handle)
> > > +{
> > > + struct pci_bus *pbus;
> > > +
> > > + if (acpi_is_root_bridge(handle)) {
> > > + struct acpi_pci_root *root = acpi_pci_find_root(handle);
> > > + pbus = root->bus;
> > > + } else {
> > > + struct pci_dev *pdev = acpi_get_pci_dev(handle);
> > > + pbus = pdev->subordinate;
> > > + pci_dev_put(pdev);
> > > + }
> > > + return pbus;
> >
> > I worry that acpi_is_root_bridge() merely checks the device IDs of
> > "handle", which isn't quite the same as checking whether the pci_root
> > driver has claimed "handle".
>
> Hm, I understand this concern in a theoretical sense, but could
> you explain more of what you're thinking about, and give me a
> concrete example of something that might go wrong here?
My concern is only theoretical -- I could imagine a PNP0A03 device
in the namespace (so acpi_is_root_bridge() is true) that has not been
claimed by the pci_root driver (so acpi_pci_find_root() returns NULL).
I don't think this will happen in practice because pci_root can't be
a module, but it's easier to analyze with just one check, since you
can learn everything you need from acpi_pci_find_root() without also
depending on acpi_is_root_bridge().
Bjorn
* Bjorn Helgaas <[email protected]>:
> On Tuesday 21 July 2009 01:57:55 pm Alex Chiang wrote:
> > * Bjorn Helgaas <[email protected]>:
> > > On Tuesday 14 July 2009 02:53:33 pm Alex Chiang wrote:
> > > > +static struct pci_bus *pci_bus_from_handle(acpi_handle handle)
> > > > +{
> > > > + struct pci_bus *pbus;
> > > > +
> > > > + if (acpi_is_root_bridge(handle)) {
> > > > + struct acpi_pci_root *root = acpi_pci_find_root(handle);
> > > > + pbus = root->bus;
> > > > + } else {
> > > > + struct pci_dev *pdev = acpi_get_pci_dev(handle);
> > > > + pbus = pdev->subordinate;
> > > > + pci_dev_put(pdev);
> > > > + }
> > > > + return pbus;
> > >
> > > I worry that acpi_is_root_bridge() merely checks the device IDs of
> > > "handle", which isn't quite the same as checking whether the pci_root
> > > driver has claimed "handle".
> >
> > Hm, I understand this concern in a theoretical sense, but could
> > you explain more of what you're thinking about, and give me a
> > concrete example of something that might go wrong here?
>
> My concern is only theoretical -- I could imagine a PNP0A03 device
> in the namespace (so acpi_is_root_bridge() is true) that has not been
> claimed by the pci_root driver (so acpi_pci_find_root() returns NULL).
>
> I don't think this will happen in practice because pci_root can't be
> a module, but it's easier to analyze with just one check, since you
> can learn everything you need from acpi_pci_find_root() without also
> depending on acpi_is_root_bridge().
Ah, that makes sense.
I can respin one more time using your suggestion (although I'll
probably keep it factored out into a separate function).
Thanks.
/ac