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Subject[PATCH 2/2] drivers: base: add coredump driver ops
Date
From: Arend van Spriel <aspriel@gmail.com>

This adds the coredump driver operation. When the driver defines it
a coredump file is added in the sysfs folder of the device upon
driver binding. The file is removed when the driver is unbound.
User-space can trigger a coredump for this device by echo'ing to
the coredump file.

Signed-off-by: Arend van Spriel <aspriel@gmail.com>
---
drivers/base/dd.c | 40 +++++++++++++++++++++++++++++++++-------
include/linux/device.h | 2 +-
2 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 533c82f..de6fd09 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -288,6 +288,18 @@ static void driver_bound(struct device *dev)
kobject_uevent(&dev->kobj, KOBJ_BIND);
}

+static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ device_lock(dev);
+ if (dev->driver->coredump)
+ dev->driver->coredump(dev);
+ device_unlock(dev);
+
+ return count;
+}
+static DEVICE_ATTR_WO(coredump);
+
static int driver_sysfs_add(struct device *dev)
{
int ret;
@@ -297,14 +309,26 @@ static int driver_sysfs_add(struct device *dev)
BUS_NOTIFY_BIND_DRIVER, dev);

ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
+ kobject_name(&dev->kobj));
+ if (ret)
+ goto fail;
+
+ ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
+ "driver");
+ if (ret)
+ goto rm_dev;
+
+ if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
+ !device_create_file(dev, &dev_attr_coredump))
+ return 0;
+
+ sysfs_remove_link(&dev->kobj, "driver");
+
+rm_dev:
+ sysfs_remove_link(&dev->driver->p->kobj,
kobject_name(&dev->kobj));
- if (ret == 0) {
- ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
- "driver");
- if (ret)
- sysfs_remove_link(&dev->driver->p->kobj,
- kobject_name(&dev->kobj));
- }
+
+fail:
return ret;
}

@@ -313,6 +337,8 @@ static void driver_sysfs_remove(struct device *dev)
struct device_driver *drv = dev->driver;

if (drv) {
+ if (drv->coredump)
+ device_remove_file(dev, &dev_attr_coredump);
sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
sysfs_remove_link(&dev->kobj, "driver");
}
diff --git a/include/linux/device.h b/include/linux/device.h
index 46cece5..cd3b47e 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -287,6 +287,7 @@ struct device_driver {
const struct attribute_group **groups;

const struct dev_pm_ops *pm;
+ int (*coredump) (struct device *dev);

struct driver_private *p;
};
@@ -300,7 +301,6 @@ extern struct device_driver *driver_find(const char *name,
extern int driver_probe_done(void);
extern void wait_for_device_probe(void);

-
/* sysfs interface for exporting driver attributes */

struct driver_attribute {
--
1.9.1
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