[PATCH 13/14] s390: use device_remove_file_self() instead of device_schedule_callback()

Tejun Heo
2014-01-10T13:48:26Z

driver-core now supports synchrnous self-deletion of attributes and
the asynchrnous removal mechanism is scheduled for removal. Use it
instead of device_schedule_callback().

* Conversions in arch/s390/pci/pci_sysfs.c and
drivers/s390/block/dcssblk.c are straightforward.

* drivers/s390/cio/ccwgroup.c is a bit more tricky because
ccwgroup_notifier() was (ab)using device_schedule_callback() to
purely obtain a process context to kick off ungroup operation which
may block from a notifier callback.

Rename ccwgroup_ungroup_callback() to ccwgroup_ungroup() and make it
take ccwgroup_device * instead. The new function is now called
directly from ccwgroup_ungroup_store().

ccwgroup_notifier() chain is updated to explicitly bounce through
ccwgroup_device->ungroup_work. This also removes possible failure
from memory pressure.

Only compile-tested.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: linux-s390@vger.kernel.org
---
arch/s390/include/asm/ccwgroup.h | 1 +
arch/s390/pci/pci_sysfs.c | 18 ++++++++----------
drivers/s390/block/dcssblk.c | 14 +++++++-------
drivers/s390/cio/ccwgroup.c | 26 ++++++++++++++++----------
4 files changed, 32 insertions(+), 27 deletions(-)

diff --git a/arch/s390/include/asm/ccwgroup.h b/arch/s390/include/asm/ccwgroup.h
index 23723ce..6e670f8 100644
--- a/arch/s390/include/asm/ccwgroup.h
+++ b/arch/s390/include/asm/ccwgroup.h
@@ -23,6 +23,7 @@ struct ccwgroup_device {
unsigned int count;
struct device dev;
struct ccw_device *cdev[0];
+ struct work_struct ungroup_work;
};

/**
diff --git a/arch/s390/pci/pci_sysfs.c b/arch/s390/pci/pci_sysfs.c
index cf8a12f..ab4a913 100644
--- a/arch/s390/pci/pci_sysfs.c
+++ b/arch/s390/pci/pci_sysfs.c
@@ -48,29 +48,27 @@ static ssize_t show_pfgid(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR(pfgid, S_IRUGO, show_pfgid, NULL);

-static void recover_callback(struct device *dev)
+static ssize_t store_recover(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
{
struct pci_dev *pdev = to_pci_dev(dev);
struct zpci_dev *zdev = get_zdev(pdev);
int ret;

+ if (!device_remove_file_self(dev, attr))
+ return count;
+
pci_stop_and_remove_bus_device(pdev);
ret = zpci_disable_device(zdev);
if (ret)
- return;
+ return ret;

ret = zpci_enable_device(zdev);
if (ret)
- return;
+ return ret;

pci_rescan_bus(zdev->bus);
-}
-
-static ssize_t store_recover(struct device *dev, struct device_attribute *attr,
- const char *buf, size_t count)
-{
- int rc = device_schedule_callback(dev, recover_callback);
- return rc ? rc : count;
+ return count;
}
static DEVICE_ATTR(recover, S_IWUSR, NULL, store_recover);

diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 6eca019..2e2f454 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -304,12 +304,6 @@ dcssblk_load_segment(char *name, struct segment_info **seg_info)
return rc;
}

-static void dcssblk_unregister_callback(struct device *dev)
-{
- device_unregister(dev);
- put_device(dev);
-}
-
/*
* device attribute for switching shared/nonshared (exclusive)
* operation (show + store)
@@ -397,7 +391,13 @@ removeseg:
blk_cleanup_queue(dev_info->dcssblk_queue);
dev_info->gd->queue = NULL;
put_disk(dev_info->gd);
- rc = device_schedule_callback(dev, dcssblk_unregister_callback);
+ up_write(&dcssblk_devices_sem);
+
+ if (device_remove_file_self(dev, attr)) {
+ device_unregister(dev);
+ put_device(dev);
+ }
+ return rc;
out:
up_write(&dcssblk_devices_sem);
return rc;
diff --git a/drivers/s390/cio/ccwgroup.c b/drivers/s390/cio/ccwgroup.c
index 959135a..67b9dc9 100644
--- a/drivers/s390/cio/ccwgroup.c
+++ b/drivers/s390/cio/ccwgroup.c
@@ -168,14 +168,12 @@ static ssize_t ccwgroup_online_show(struct device *dev,
* Provide an 'ungroup' attribute so the user can remove group devices no
* longer needed or accidentially created. Saves memory :)
*/
-static void ccwgroup_ungroup_callback(struct device *dev)
+static void ccwgroup_ungroup(struct ccwgroup_device *gdev)
{
- struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
-
mutex_lock(&gdev->reg_mutex);
if (device_is_registered(&gdev->dev)) {
__ccwgroup_remove_symlinks(gdev);
- device_unregister(dev);
+ device_unregister(&gdev->dev);
__ccwgroup_remove_cdev_refs(gdev);
}
mutex_unlock(&gdev->reg_mutex);
@@ -195,10 +193,9 @@ static ssize_t ccwgroup_ungroup_store(struct device *dev,
rc = -EINVAL;
goto out;
}
- /* Note that we cannot unregister the device from one of its
- * attribute methods, so we have to use this roundabout approach.
- */
- rc = device_schedule_callback(dev, ccwgroup_ungroup_callback);
+
+ if (device_remove_file_self(dev, attr))
+ ccwgroup_ungroup(gdev);
out:
if (rc) {
if (rc != -EAGAIN)
@@ -224,6 +221,14 @@ static const struct attribute_group *ccwgroup_attr_groups[] = {
NULL,
};

+static void ccwgroup_ungroup_workfn(struct work_struct *work)
+{
+ struct ccwgroup_device *gdev =
+ container_of(work, struct ccwgroup_device, ungroup_work);
+
+ ccwgroup_ungroup(gdev);
+}
+
static void ccwgroup_release(struct device *dev)
{
kfree(to_ccwgroupdev(dev));
@@ -323,6 +328,7 @@ int ccwgroup_create_dev(struct device *parent, struct ccwgroup_driver *gdrv,
atomic_set(&gdev->onoff, 0);
mutex_init(&gdev->reg_mutex);
mutex_lock(&gdev->reg_mutex);
+ INIT_WORK(&gdev->ungroup_work, ccwgroup_ungroup_workfn);
gdev->count = num_devices;
gdev->dev.bus = &ccwgroup_bus_type;
gdev->dev.parent = parent;
@@ -404,10 +410,10 @@ EXPORT_SYMBOL(ccwgroup_create_dev);
static int ccwgroup_notifier(struct notifier_block *nb, unsigned long action,
void *data)
{
- struct device *dev = data;
+ struct ccwgroup_device *gdev = to_ccwgroupdev(data);

if (action == BUS_NOTIFY_UNBIND_DRIVER)
- device_schedule_callback(dev, ccwgroup_ungroup_callback);
+ schedule_work(&gdev->ungroup_work);

return NOTIFY_OK;
}
--
1.8.4.2