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Message-ID: <146507355828.8347.11600179233094511139.stgit@dwillia2-desk3.amr.corp.intel.com>
Date: Sat, 04 Jun 2016 13:52:38 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: linux-nvdimm@...ts.01.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
david@...morbit.com, linux-kernel@...r.kernel.org, hch@....de
Subject: [PATCH 01/13] driver core,
libnvdimm: disable manual unbind of dimms while region active
There are scenarios where we need a middle ground between disabling all
manual bind/unbind attempts (via driver->suppress_bind_attrs) and
allowing unbind at any userspace-determined time. Pinning modules takes
away one vector for unwanted out-of-sequence device_release_driver()
invocations, this new mechanism (via device->suppress_unbind_attr) takes
away another.
The first user of this mechanism is the libnvdimm sub-system where
manual dimm disabling should be prevented while the dimm is active in
any region. Note that there is a 1:N dimm-to-region relationship which
is why this is implemented as a disable count rather than a flag. This
forces userspace to disable regions before dimms when manually shutting
down a bus topology.
This does not affect any of the kernel-internal initiated invocations of
device_release_driver().
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
drivers/base/base.h | 1 +
drivers/base/bus.c | 12 ++++++++++--
drivers/base/core.c | 1 +
drivers/base/dd.c | 2 +-
drivers/nvdimm/namespace_devs.c | 1 +
drivers/nvdimm/region_devs.c | 4 +++-
include/linux/device.h | 20 ++++++++++++++++++++
7 files changed, 37 insertions(+), 4 deletions(-)
diff --git a/drivers/base/base.h b/drivers/base/base.h
index e05db388bd1c..129814b17ca6 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -109,6 +109,7 @@ extern int bus_add_driver(struct device_driver *drv);
extern void bus_remove_driver(struct device_driver *drv);
extern void driver_detach(struct device_driver *drv);
+extern void __device_release_driver(struct device *dev);
extern int driver_probe_device(struct device_driver *drv, struct device *dev);
extern void driver_deferred_probe_del(struct device *dev);
static inline int driver_match_device(struct device_driver *drv,
diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 6470eb8088f4..b48a903f2d28 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -188,10 +188,18 @@ static ssize_t unbind_store(struct device_driver *drv, const char *buf,
if (dev && dev->driver == drv) {
if (dev->parent) /* Needed for USB */
device_lock(dev->parent);
- device_release_driver(dev);
+
+ device_lock(dev);
+ if (atomic_read(&dev->suppress_unbind_attr) > 0)
+ err = -EBUSY;
+ else {
+ __device_release_driver(dev);
+ err = count;
+ }
+ device_unlock(dev);
+
if (dev->parent)
device_unlock(dev->parent);
- err = count;
}
put_device(dev);
bus_put(bus);
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 0a8bdade53f2..0ea0e8560e1d 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -708,6 +708,7 @@ void device_initialize(struct device *dev)
INIT_LIST_HEAD(&dev->devres_head);
device_pm_init(dev);
set_dev_node(dev, -1);
+ atomic_set(&dev->suppress_unbind_attr, 0);
#ifdef CONFIG_GENERIC_MSI_IRQ
INIT_LIST_HEAD(&dev->msi_list);
#endif
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 16688f50729c..9e21817ca2d6 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -756,7 +756,7 @@ EXPORT_SYMBOL_GPL(driver_attach);
* __device_release_driver() must be called with @dev lock held.
* When called for a USB interface, @dev->parent lock must be held as well.
*/
-static void __device_release_driver(struct device *dev)
+void __device_release_driver(struct device *dev)
{
struct device_driver *drv;
diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index c5e3196c45b0..e65572b6092c 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -1950,6 +1950,7 @@ static int init_active_labels(struct nd_region *nd_region)
}
nd_mapping->ndd = ndd;
atomic_inc(&nvdimm->busy);
+ device_disable_unbind_attr(&nvdimm->dev);
get_ndd(ndd);
count = nd_label_active_count(ndd);
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index 40fcfea26fbb..320f0f3ea367 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -427,8 +427,10 @@ static void nd_region_notify_driver_action(struct nvdimm_bus *nvdimm_bus,
nd_mapping->labels = NULL;
put_ndd(ndd);
nd_mapping->ndd = NULL;
- if (ndd)
+ if (ndd) {
atomic_dec(&nvdimm->busy);
+ device_enable_unbind_attr(&nvdimm->dev);
+ }
}
if (is_nd_pmem(dev))
diff --git a/include/linux/device.h b/include/linux/device.h
index 38f02814d53a..d9eaa85bb9cf 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -849,6 +849,7 @@ struct device {
void (*release)(struct device *dev);
struct iommu_group *iommu_group;
+ atomic_t suppress_unbind_attr; /* disable manual unbind */
bool offline_disabled:1;
bool offline:1;
@@ -988,6 +989,25 @@ static inline void device_lock_assert(struct device *dev)
lockdep_assert_held(&dev->mutex);
}
+static inline bool device_disable_unbind_attr(struct device *dev)
+{
+ bool suppressed = false;
+
+ device_lock(dev);
+ if (dev->driver) {
+ atomic_inc(&dev->suppress_unbind_attr);
+ suppressed = true;
+ }
+ device_unlock(dev);
+
+ return suppressed;
+}
+
+static inline bool device_enable_unbind_attr(struct device *dev)
+{
+ return atomic_dec_and_test(&dev->suppress_unbind_attr);
+}
+
static inline struct device_node *dev_of_node(struct device *dev)
{
if (!IS_ENABLED(CONFIG_OF))
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