Commit b70d31d0 authored by Dan Williams's avatar Dan Williams
Browse files

libnvdimm/bus: Stop holding nvdimm_bus_list_mutex over __nd_ioctl() 



In preparation for fixing a deadlock between wait_for_bus_probe_idle()
and the nvdimm_bus_list_mutex arrange for __nd_ioctl() without
nvdimm_bus_list_mutex held. This also unifies the 'dimm' and 'bus' level
ioctls into a common nd_ioctl() preamble implementation.

Marked for -stable as it is a pre-requisite for a follow-on fix.

Cc: <stable@vger.kernel.org>
Fixes: bf9bccc1 ("libnvdimm: pmem label sets and namespace instantiation")
Cc: Vishal Verma <vishal.l.verma@intel.com>
Tested-by: default avatarJane Chu <jane.chu@oracle.com>
Link: https://lore.kernel.org/r/156341209518.292348.7183897251740665198.stgit@dwillia2-desk3.amr.corp.intel.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 6de5d06e

drivers/nvdimm/bus.c

+58 −38
Original line number Diff line number Diff line
@@ -73,7 +73,7 @@ static void nvdimm_bus_probe_end(struct nvdimm_bus *nvdimm_bus) 
{

	nvdimm_bus_lock(&nvdimm_bus->dev);

	if (--nvdimm_bus->probe_active == 0)

		wake_up(&nvdimm_bus->probe_wait);

		wake_up(&nvdimm_bus->wait);

	nvdimm_bus_unlock(&nvdimm_bus->dev);

}
@@ -341,7 +341,7 @@ struct nvdimm_bus *nvdimm_bus_register(struct device *parent, 
		return NULL;

	INIT_LIST_HEAD(&nvdimm_bus->list);

	INIT_LIST_HEAD(&nvdimm_bus->mapping_list);

	init_waitqueue_head(&nvdimm_bus->probe_wait);

	init_waitqueue_head(&nvdimm_bus->wait);

	nvdimm_bus->id = ida_simple_get(&nd_ida, 0, 0, GFP_KERNEL);

	if (nvdimm_bus->id < 0) {

		kfree(nvdimm_bus);
@@ -426,6 +426,9 @@ static int nd_bus_remove(struct device *dev) 
	list_del_init(&nvdimm_bus->list);

	mutex_unlock(&nvdimm_bus_list_mutex);



	wait_event(nvdimm_bus->wait,

			atomic_read(&nvdimm_bus->ioctl_active) == 0);



	nd_synchronize();

	device_for_each_child(&nvdimm_bus->dev, NULL, child_unregister);
@@ -885,7 +888,7 @@ void wait_nvdimm_bus_probe_idle(struct device *dev) 
		if (nvdimm_bus->probe_active == 0)

			break;

		nvdimm_bus_unlock(&nvdimm_bus->dev);

		wait_event(nvdimm_bus->probe_wait,

		wait_event(nvdimm_bus->wait,

				nvdimm_bus->probe_active == 0);

		nvdimm_bus_lock(&nvdimm_bus->dev);

	} while (true);
@@ -1130,24 +1133,10 @@ out: 
	return rc;

}



static long nd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

{

	long id = (long) file->private_data;

	int rc = -ENXIO, ro;

	struct nvdimm_bus *nvdimm_bus;



	ro = ((file->f_flags & O_ACCMODE) == O_RDONLY);

	mutex_lock(&nvdimm_bus_list_mutex);

	list_for_each_entry(nvdimm_bus, &nvdimm_bus_list, list) {

		if (nvdimm_bus->id == id) {

			rc = __nd_ioctl(nvdimm_bus, NULL, ro, cmd, arg);

			break;

		}

	}

	mutex_unlock(&nvdimm_bus_list_mutex);



	return rc;

}

enum nd_ioctl_mode {

	BUS_IOCTL,

	DIMM_IOCTL,

};



static int match_dimm(struct device *dev, void *data)

{
@@ -1162,31 +1151,62 @@ static int match_dimm(struct device *dev, void *data) 
	return 0;

}



static long nvdimm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

static long nd_ioctl(struct file *file, unsigned int cmd, unsigned long arg,

		enum nd_ioctl_mode mode)



{

	int rc = -ENXIO, ro;

	struct nvdimm_bus *nvdimm_bus;

	struct nvdimm_bus *nvdimm_bus, *found = NULL;

	long id = (long) file->private_data;

	struct nvdimm *nvdimm = NULL;

	int rc, ro;



	ro = ((file->f_flags & O_ACCMODE) == O_RDONLY);

	mutex_lock(&nvdimm_bus_list_mutex);

	list_for_each_entry(nvdimm_bus, &nvdimm_bus_list, list) {

		struct device *dev = device_find_child(&nvdimm_bus->dev,

				file->private_data, match_dimm);

		struct nvdimm *nvdimm;

		if (mode == DIMM_IOCTL) {

			struct device *dev;



			dev = device_find_child(&nvdimm_bus->dev,

					file->private_data, match_dimm);

			if (!dev)

				continue;



			nvdimm = to_nvdimm(dev);

		rc = __nd_ioctl(nvdimm_bus, nvdimm, ro, cmd, arg);

		put_device(dev);

			found = nvdimm_bus;

		} else if (nvdimm_bus->id == id) {

			found = nvdimm_bus;

		}



		if (found) {

			atomic_inc(&nvdimm_bus->ioctl_active);

			break;

		}

	}

	mutex_unlock(&nvdimm_bus_list_mutex);



	if (!found)

		return -ENXIO;



	nvdimm_bus = found;

	rc = __nd_ioctl(nvdimm_bus, nvdimm, ro, cmd, arg);



	if (nvdimm)

		put_device(&nvdimm->dev);

	if (atomic_dec_and_test(&nvdimm_bus->ioctl_active))

		wake_up(&nvdimm_bus->wait);



	return rc;

}



static long bus_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

{

	return nd_ioctl(file, cmd, arg, BUS_IOCTL);

}



static long dimm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

{

	return nd_ioctl(file, cmd, arg, DIMM_IOCTL);

}



static int nd_open(struct inode *inode, struct file *file)

{

	long minor = iminor(inode);
@@ -1198,16 +1218,16 @@ static int nd_open(struct inode *inode, struct file *file) 
static const struct file_operations nvdimm_bus_fops = {

	.owner = THIS_MODULE,

	.open = nd_open,

	.unlocked_ioctl = nd_ioctl,

	.compat_ioctl = nd_ioctl,

	.unlocked_ioctl = bus_ioctl,

	.compat_ioctl = bus_ioctl,

	.llseek = noop_llseek,

};



static const struct file_operations nvdimm_fops = {

	.owner = THIS_MODULE,

	.open = nd_open,

	.unlocked_ioctl = nvdimm_ioctl,

	.compat_ioctl = nvdimm_ioctl,

	.unlocked_ioctl = dimm_ioctl,

	.compat_ioctl = dimm_ioctl,

	.llseek = noop_llseek,

};

drivers/nvdimm/nd-core.h

+2 −1
Original line number Diff line number Diff line
@@ -17,10 +17,11 @@ extern struct workqueue_struct *nvdimm_wq; 


struct nvdimm_bus {

	struct nvdimm_bus_descriptor *nd_desc;

	wait_queue_head_t probe_wait;

	wait_queue_head_t wait;

	struct list_head list;

	struct device dev;

	int id, probe_active;

	atomic_t ioctl_active;

	struct list_head mapping_list;

	struct mutex reconfig_mutex;

	struct badrange badrange;

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