Revert "s390: use device_remove_file_self() instead of device_schedule_callback()"

This reverts commit bdbb0a1376635d80e096f6433595a38984cf5408.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: 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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

4 files changed, 27 insertions, 32 deletions

diff --git a/arch/s390/include/asm/ccwgroup.h b/arch/s390/include/asm/ccwgroup.h
index 6e670f88d125..23723ce5ca7a 100644
--- a/arch/s390/include/asm/ccwgroup.h
+++ b/arch/s390/include/asm/ccwgroup.h
@@ -23,7 +23,6 @@ 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 ab4a91393005..cf8a12ff733b 100644
--- a/arch/s390/pci/pci_sysfs.c
+++ b/arch/s390/pci/pci_sysfs.c
@@ -48,27 +48,29 @@ static ssize_t show_pfgid(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR(pfgid, S_IRUGO, show_pfgid, NULL);
 
-static ssize_t store_recover(struct device *dev, struct device_attribute *attr,
-                             const char *buf, size_t count)
+static void recover_callback(struct device *dev)
 {
         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 ret;
+                return;
 
         ret = zpci_enable_device(zdev);
         if (ret)
-                return ret;
+                return;
 
         pci_rescan_bus(zdev->bus);
-        return count;
+}
+
+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;
 }
 static DEVICE_ATTR(recover, S_IWUSR, NULL, store_recover);
 
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 2e2f454a05a1..6eca019bcf30 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -304,6 +304,12 @@ 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)
@@ -391,13 +397,7 @@ removeseg:
         blk_cleanup_queue(dev_info->dcssblk_queue);
         dev_info->gd->queue = NULL;
         put_disk(dev_info->gd);
-        up_write(&dcssblk_devices_sem);
-
-        if (device_remove_file_self(dev, attr)) {
-                device_unregister(dev);
-                put_device(dev);
-        }
-        return rc;
+        rc = device_schedule_callback(dev, dcssblk_unregister_callback);
 out:
         up_write(&dcssblk_devices_sem);
         return rc;
diff --git a/drivers/s390/cio/ccwgroup.c b/drivers/s390/cio/ccwgroup.c
index 67b9dc9044c2..959135a01847 100644
--- a/drivers/s390/cio/ccwgroup.c
+++ b/drivers/s390/cio/ccwgroup.c
@@ -168,12 +168,14 @@ 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(struct ccwgroup_device *gdev)
+static void ccwgroup_ungroup_callback(struct device *dev)
 {
+        struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
+
         mutex_lock(&gdev->reg_mutex);
         if (device_is_registered(&gdev->dev)) {
                 __ccwgroup_remove_symlinks(gdev);
-                device_unregister(&gdev->dev);
+                device_unregister(dev);
                 __ccwgroup_remove_cdev_refs(gdev);
         }
         mutex_unlock(&gdev->reg_mutex);
@@ -193,9 +195,10 @@ static ssize_t ccwgroup_ungroup_store(struct device *dev,
                 rc = -EINVAL;
                 goto out;
         }
-
-        if (device_remove_file_self(dev, attr))
-                ccwgroup_ungroup(gdev);
+        /* 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);
 out:
         if (rc) {
                 if (rc != -EAGAIN)
@@ -221,14 +224,6 @@ 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));
@@ -328,7 +323,6 @@ 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;
@@ -410,10 +404,10 @@ EXPORT_SYMBOL(ccwgroup_create_dev);
 static int ccwgroup_notifier(struct notifier_block *nb, unsigned long action,
                              void *data)
 {
-        struct ccwgroup_device *gdev = to_ccwgroupdev(data);
+        struct device *dev = data;
 
         if (action == BUS_NOTIFY_UNBIND_DRIVER)
-                schedule_work(&gdev->ungroup_work);
+                device_schedule_callback(dev, ccwgroup_ungroup_callback);
 
         return NOTIFY_OK;
 }