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Date: Mon, 19 Nov 2012 13:33:43 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
Jean Delvare <khali@...ux-fr.org>, ben-linux@...ff.org,
w.sang@...gutronix.de, linux-kernel@...r.kernel.org,
lenb@...nel.org, rafael.j.wysocki@...el.com,
broonie@...nsource.wolfsonmicro.com, grant.likely@...retlab.ca,
linus.walleij@...aro.org, mathias.nyman@...ux.intel.com,
linux-acpi@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [Update][PATCH 1/2] ACPI: Allow ACPI handles of devices to be initialized in advance
On Monday, November 19, 2012 11:42:34 AM Mika Westerberg wrote:
> On Sun, Nov 18, 2012 at 10:12:52PM +0100, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >
> > Currently, the ACPI handles of devices are initialized from within
> > device_add(), by acpi_bind_one() called from acpi_platform_notify()
> > which first uses the .find_device() routine provided by the device's
> > bus type to find the matching device node in the ACPI namespace.
> > This is a source of some computational overhead and, moreover, the
> > correctness of the result depends on the implementation of
> > .find_device() which is known to fail occasionally for some bus types
> > (e.g. PCI). In some cases, however, the corresponding ACPI device
> > node is known already before calling device_add() for the given
> > struct device object and the whole .find_device() dance in
> > acpi_platform_notify() is then simply unnecessary.
> >
> > For this reason, make it possible to initialize the ACPI handles of
> > devices before calling device_add() for them. Modify
> > acpi_platform_notify() to call acpi_bind_one() in advance to check
> > the device's existing ACPI handle and skip the .find_device()
> > search if that is successful. Change acpi_bind_one() accordingly.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > ---
> > drivers/acpi/glue.c | 42 +++++++++++++++++++++++++++++++++---------
> > 1 file changed, 33 insertions(+), 9 deletions(-)
> >
> > Index: linux/drivers/acpi/glue.c
> > ===================================================================
> > --- linux.orig/drivers/acpi/glue.c
> > +++ linux/drivers/acpi/glue.c
> > @@ -135,41 +135,54 @@ static int acpi_bind_one(struct device *
> > int retval = -EINVAL;
> >
> > if (dev->acpi_handle) {
> > - dev_warn(dev, "Drivers changed 'acpi_handle'\n");
> > - return -EINVAL;
> > + if (handle) {
> > + dev_warn(dev, "ACPI handle is already set\n");
> > + return -EINVAL;
> > + } else {
> > + handle = dev->acpi_handle;
> > + }
> > }
> > + if (!handle)
> > + return -EINVAL;
> >
> > get_device(dev);
> > status = acpi_bus_get_device(handle, &acpi_dev);
> > if (ACPI_FAILURE(status))
> > goto err;
> >
> > - physical_node = kzalloc(sizeof(struct acpi_device_physical_node),
> > - GFP_KERNEL);
> > + physical_node = kzalloc(sizeof(*physical_node), GFP_KERNEL);
>
> Here we allocate memory for the physical node...
>
> > if (!physical_node) {
> > retval = -ENOMEM;
> > goto err;
> > }
> >
> > mutex_lock(&acpi_dev->physical_node_lock);
> > +
> > + /* Sanity check. */
> > + list_for_each_entry(physical_node, &acpi_dev->physical_node_list, node)
>
> .. and overwrite it here ;-)
Ah, good catch!
> Maybe using a different variable for the sanity check?
Yeah, I wanted to be overly smart. :-)
> I've changed the SPI/I2C patches to use this as well and they got a lot
> smaller as we don't have to do the .find_device() magic.
>
> Once you have fixed the above, you can add my
>
> Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
>
> to these two patches, if you like.
I will.
In the meantime, updated patch is appended.
Thanks,
Rafael
---
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Subject: ACPI: Allow ACPI handles of devices to be initialized in advance
Currently, the ACPI handles of devices are initialized from within
device_add(), by acpi_bind_one() called from acpi_platform_notify()
which first uses the .find_device() routine provided by the device's
bus type to find the matching device node in the ACPI namespace.
This is a source of some computational overhead and, moreover, the
correctness of the result depends on the implementation of
.find_device() which is known to fail occasionally for some bus types
(e.g. PCI). In some cases, however, the corresponding ACPI device
node is known already before calling device_add() for the given
struct device object and the whole .find_device() dance in
acpi_platform_notify() is then simply unnecessary.
For this reason, make it possible to initialize the ACPI handles of
devices before calling device_add() for them. Modify
acpi_platform_notify() to call acpi_bind_one() in advance to check
the device's existing ACPI handle and skip the .find_device()
search if that is successful. Change acpi_bind_one() accordingly.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
drivers/acpi/glue.c | 44 ++++++++++++++++++++++++++++++++++----------
1 file changed, 34 insertions(+), 10 deletions(-)
Index: linux/drivers/acpi/glue.c
===================================================================
--- linux.orig/drivers/acpi/glue.c
+++ linux/drivers/acpi/glue.c
@@ -130,46 +130,59 @@ static int acpi_bind_one(struct device *
{
struct acpi_device *acpi_dev;
acpi_status status;
- struct acpi_device_physical_node *physical_node;
+ struct acpi_device_physical_node *physical_node, *pn;
char physical_node_name[sizeof(PHYSICAL_NODE_STRING) + 2];
int retval = -EINVAL;
if (dev->acpi_handle) {
- dev_warn(dev, "Drivers changed 'acpi_handle'\n");
- return -EINVAL;
+ if (handle) {
+ dev_warn(dev, "ACPI handle is already set\n");
+ return -EINVAL;
+ } else {
+ handle = dev->acpi_handle;
+ }
}
+ if (!handle)
+ return -EINVAL;
get_device(dev);
status = acpi_bus_get_device(handle, &acpi_dev);
if (ACPI_FAILURE(status))
goto err;
- physical_node = kzalloc(sizeof(struct acpi_device_physical_node),
- GFP_KERNEL);
+ physical_node = kzalloc(sizeof(*physical_node), GFP_KERNEL);
if (!physical_node) {
retval = -ENOMEM;
goto err;
}
mutex_lock(&acpi_dev->physical_node_lock);
+
+ /* Sanity check. */
+ list_for_each_entry(pn, &acpi_dev->physical_node_list, node)
+ if (pn->dev == dev) {
+ dev_warn(dev, "Already associated with ACPI node\n");
+ goto err_free;
+ }
+
/* allocate physical node id according to physical_node_id_bitmap */
physical_node->node_id =
find_first_zero_bit(acpi_dev->physical_node_id_bitmap,
ACPI_MAX_PHYSICAL_NODE);
if (physical_node->node_id >= ACPI_MAX_PHYSICAL_NODE) {
retval = -ENOSPC;
- mutex_unlock(&acpi_dev->physical_node_lock);
- kfree(physical_node);
- goto err;
+ goto err_free;
}
set_bit(physical_node->node_id, acpi_dev->physical_node_id_bitmap);
physical_node->dev = dev;
list_add_tail(&physical_node->node, &acpi_dev->physical_node_list);
acpi_dev->physical_node_count++;
+
mutex_unlock(&acpi_dev->physical_node_lock);
- dev->acpi_handle = handle;
+ if (!dev->acpi_handle)
+ dev->acpi_handle = handle;
if (!physical_node->node_id)
strcpy(physical_node_name, PHYSICAL_NODE_STRING);
@@ -187,8 +200,14 @@ static int acpi_bind_one(struct device *
return 0;
err:
+ dev->acpi_handle = NULL;
put_device(dev);
return retval;
+
+ err_free:
+ mutex_unlock(&acpi_dev->physical_node_lock);
+ kfree(physical_node);
+ goto err;
}
static int acpi_unbind_one(struct device *dev)
@@ -247,6 +266,10 @@ static int acpi_platform_notify(struct d
acpi_handle handle;
int ret = -EINVAL;
+ ret = acpi_bind_one(dev, NULL);
+ if (!ret)
+ goto out;
+
if (!dev->bus || !dev->parent) {
/* bridge devices genernally haven't bus or parent */
ret = acpi_find_bridge_device(dev, &handle);
@@ -260,10 +283,11 @@ static int acpi_platform_notify(struct d
}
if ((ret = type->find_device(dev, &handle)) != 0)
DBG("Can't get handler for %s\n", dev_name(dev));
- end:
+ end:
if (!ret)
acpi_bind_one(dev, handle);
+ out:
#if ACPI_GLUE_DEBUG
if (!ret) {
struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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