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Subject[PATCH] driver core: Move driver_data back to struct device
Having to allocate memory as part of dev_set_drvdata() is a problem
because that memory may never get freed if the device itself is not
created. So move driver_data back to struct device.

This is a partial revert of commit b4028437.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Greg, we discussed that back in January (in a thread named "Freeing of
dev->p") but I did not hear back from you and I can't see this fix in
your driver-core tree.

As discussed in that thread, really reverting b4028437 might be an even
better option, performance-wise. If we do that, we'll first have to
update drivers/iommu/exynos-iommu.c and drivers/vfio/vfio.c to no
longer check for the return value of dev_set_drvdata(). I can provide
the patches, if you're fine with that.

drivers/base/base.h | 3 ---
drivers/base/dd.c | 13 +++----------
include/linux/device.h | 4 ++++
3 files changed, 7 insertions(+), 13 deletions(-)

--- linux-3.15-rc0.orig/drivers/base/base.h 2014-04-07 10:32:56.429667887 +0200
+++ linux-3.15-rc0/drivers/base/base.h 2014-04-07 10:32:59.598734941 +0200
@@ -63,8 +63,6 @@ struct driver_private {
* binding of drivers which were unable to get all the resources needed by
* the device; typically because it depends on another driver getting
* probed first.
- * @driver_data - private pointer for driver specific info. Will turn into a
- * list soon.
* @device - pointer back to the struct class that this structure is
* associated with.
*
@@ -76,7 +74,6 @@ struct device_private {
struct klist_node knode_driver;
struct klist_node knode_bus;
struct list_head deferred_probe;
- void *driver_data;
struct device *device;
};
#define to_device_private_parent(obj) \
--- linux-3.15-rc0.orig/drivers/base/dd.c 2014-04-07 10:32:56.429667887 +0200
+++ linux-3.15-rc0/drivers/base/dd.c 2014-04-07 10:32:59.599734962 +0200
@@ -577,22 +577,15 @@ void driver_detach(struct device_driver
*/
void *dev_get_drvdata(const struct device *dev)
{
- if (dev && dev->p)
- return dev->p->driver_data;
+ if (dev)
+ return dev->driver_data;
return NULL;
}
EXPORT_SYMBOL(dev_get_drvdata);

int dev_set_drvdata(struct device *dev, void *data)
{
- int error;
-
- if (!dev->p) {
- error = device_private_init(dev);
- if (error)
- return error;
- }
- dev->p->driver_data = data;
+ dev->driver_data = data;
return 0;
}
EXPORT_SYMBOL(dev_set_drvdata);
--- linux-3.15-rc0.orig/include/linux/device.h 2014-04-07 10:32:56.429667887 +0200
+++ linux-3.15-rc0/include/linux/device.h 2014-04-07 10:32:59.599734962 +0200
@@ -679,6 +679,8 @@ struct acpi_dev_node {
* variants, which GPIO pins act in what additional roles, and so
* on. This shrinks the "Board Support Packages" (BSPs) and
* minimizes board-specific #ifdefs in drivers.
+ * @driver_data: Private pointer for driver specific info. Will turn into a
+ * list soon.
* @power: For device power management.
* See Documentation/power/devices.txt for details.
* @pm_domain: Provide callbacks that are executed during system suspend,
@@ -740,6 +742,8 @@ struct device {
device */
void *platform_data; /* Platform specific data, device
core doesn't touch it */
+ void *driver_data; /* Driver data, set and get with
+ dev_set/get_drvdata */
struct dev_pm_info power;
struct dev_pm_domain *pm_domain;


--
Jean Delvare
SUSE L3 Support


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