Commit 3c5b9039 authored by Dan Williams's avatar Dan Williams
Browse files

cxl: Prove CXL locking 



When CONFIG_PROVE_LOCKING is enabled the 'struct device' definition gets
an additional mutex that is not clobbered by
lockdep_set_novalidate_class() like the typical device_lock(). This
allows for local annotation of subsystem locks with mutex_lock_nested()
per the subsystem's object/lock hierarchy. For CXL, this primarily needs
the ability to lock ports by depth and child objects of ports by their
parent parent-port lock.

Reviewed-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: default avatarBen Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/164365853422.99383.1052399160445197427.stgit@dwillia2-desk3.amr.corp.intel.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 53fa1bff

drivers/cxl/acpi.c

+5 −5
Original line number Diff line number Diff line
@@ -176,14 +176,14 @@ static struct cxl_dport *find_dport_by_dev(struct cxl_port *port, struct device 
{

	struct cxl_dport *dport;



	device_lock(&port->dev);

	cxl_device_lock(&port->dev);

	list_for_each_entry(dport, &port->dports, list)

		if (dport->dport == dev) {

			device_unlock(&port->dev);

			cxl_device_unlock(&port->dev);

			return dport;

		}



	device_unlock(&port->dev);

	cxl_device_unlock(&port->dev);

	return NULL;

}
@@ -264,9 +264,9 @@ static int add_host_bridge_uport(struct device *match, void *arg) 
	if (IS_ERR(cxld))

		return PTR_ERR(cxld);



	device_lock(&port->dev);

	cxl_device_lock(&port->dev);

	dport = list_first_entry(&port->dports, typeof(*dport), list);

	device_unlock(&port->dev);

	cxl_device_unlock(&port->dev);



	single_port_map[0] = dport->port_id;

drivers/cxl/core/pmem.c

+2 −2
Original line number Diff line number Diff line
@@ -115,10 +115,10 @@ static void unregister_nvb(void *_cxl_nvb) 
	 * work to flush. Once the state has been changed to 'dead' then no new

	 * work can be queued by user-triggered bind.

	 */

	device_lock(&cxl_nvb->dev);

	cxl_device_lock(&cxl_nvb->dev);

	flush = cxl_nvb->state != CXL_NVB_NEW;

	cxl_nvb->state = CXL_NVB_DEAD;

	device_unlock(&cxl_nvb->dev);

	cxl_device_unlock(&cxl_nvb->dev);



	/*

	 * Even though the device core will trigger device_release_driver()

drivers/cxl/core/port.c

+36 −11
Original line number Diff line number Diff line
@@ -111,7 +111,7 @@ static ssize_t target_list_show(struct device *dev, 
	ssize_t offset = 0;

	int i, rc = 0;



	device_lock(dev);

	cxl_device_lock(dev);

	for (i = 0; i < cxld->interleave_ways; i++) {

		struct cxl_dport *dport = cxld->target[i];

		struct cxl_dport *next = NULL;
@@ -127,7 +127,7 @@ static ssize_t target_list_show(struct device *dev, 
			break;

		offset += rc;

	}

	device_unlock(dev);

	cxl_device_unlock(dev);



	if (rc < 0)

		return rc;
@@ -214,6 +214,12 @@ bool is_root_decoder(struct device *dev) 
}

EXPORT_SYMBOL_NS_GPL(is_root_decoder, CXL);



bool is_cxl_decoder(struct device *dev)

{

	return dev->type->release == cxl_decoder_release;

}

EXPORT_SYMBOL_NS_GPL(is_cxl_decoder, CXL);



struct cxl_decoder *to_cxl_decoder(struct device *dev)

{

	if (dev_WARN_ONCE(dev, dev->type->release != cxl_decoder_release,
@@ -235,10 +241,10 @@ static void cxl_port_release(struct device *dev) 
	struct cxl_port *port = to_cxl_port(dev);

	struct cxl_dport *dport, *_d;



	device_lock(dev);

	cxl_device_lock(dev);

	list_for_each_entry_safe(dport, _d, &port->dports, list)

		cxl_dport_release(dport);

	device_unlock(dev);

	cxl_device_unlock(dev);

	ida_free(&cxl_port_ida, port->id);

	kfree(port);

}
@@ -254,6 +260,12 @@ static const struct device_type cxl_port_type = { 
	.groups = cxl_port_attribute_groups,

};



bool is_cxl_port(struct device *dev)

{

	return dev->type == &cxl_port_type;

}

EXPORT_SYMBOL_NS_GPL(is_cxl_port, CXL);



struct cxl_port *to_cxl_port(struct device *dev)

{

	if (dev_WARN_ONCE(dev, dev->type != &cxl_port_type,
@@ -261,13 +273,14 @@ struct cxl_port *to_cxl_port(struct device *dev) 
		return NULL;

	return container_of(dev, struct cxl_port, dev);

}

EXPORT_SYMBOL_NS_GPL(to_cxl_port, CXL);



static void unregister_port(void *_port)

{

	struct cxl_port *port = _port;

	struct cxl_dport *dport;



	device_lock(&port->dev);

	cxl_device_lock(&port->dev);

	list_for_each_entry(dport, &port->dports, list) {

		char link_name[CXL_TARGET_STRLEN];
@@ -276,7 +289,7 @@ static void unregister_port(void *_port) 
			continue;

		sysfs_remove_link(&port->dev.kobj, link_name);

	}

	device_unlock(&port->dev);

	cxl_device_unlock(&port->dev);

	device_unregister(&port->dev);

}
@@ -407,7 +420,7 @@ static int add_dport(struct cxl_port *port, struct cxl_dport *new) 
{

	struct cxl_dport *dup;



	device_lock(&port->dev);

	cxl_device_lock(&port->dev);

	dup = find_dport(port, new->port_id);

	if (dup)

		dev_err(&port->dev,
@@ -416,7 +429,7 @@ static int add_dport(struct cxl_port *port, struct cxl_dport *new) 
			dev_name(dup->dport));

	else

		list_add_tail(&new->list, &port->dports);

	device_unlock(&port->dev);

	cxl_device_unlock(&port->dev);



	return dup ? -EEXIST : 0;

}
@@ -475,7 +488,7 @@ static int decoder_populate_targets(struct cxl_decoder *cxld, 
	if (!target_map)

		return 0;



	device_lock(&port->dev);

	cxl_device_lock(&port->dev);

	if (list_empty(&port->dports)) {

		rc = -EINVAL;

		goto out_unlock;
@@ -492,7 +505,7 @@ static int decoder_populate_targets(struct cxl_decoder *cxld, 
	}



out_unlock:

	device_unlock(&port->dev);

	cxl_device_unlock(&port->dev);



	return rc;

}
@@ -717,15 +730,27 @@ static int cxl_bus_match(struct device *dev, struct device_driver *drv) 


static int cxl_bus_probe(struct device *dev)

{

	return to_cxl_drv(dev->driver)->probe(dev);

	int rc;



	/*

	 * Take the CXL nested lock since the driver core only holds

	 * @dev->mutex and not @dev->lockdep_mutex.

	 */

	cxl_nested_lock(dev);

	rc = to_cxl_drv(dev->driver)->probe(dev);

	cxl_nested_unlock(dev);



	return rc;

}



static void cxl_bus_remove(struct device *dev)

{

	struct cxl_driver *cxl_drv = to_cxl_drv(dev->driver);



	cxl_nested_lock(dev);

	if (cxl_drv->remove)

		cxl_drv->remove(dev);

	cxl_nested_unlock(dev);

}



struct bus_type cxl_bus_type = {

drivers/cxl/cxl.h

+81 −0
Original line number Diff line number Diff line
@@ -291,6 +291,7 @@ static inline bool is_cxl_root(struct cxl_port *port) 
	return port->uport == port->dev.parent;

}



bool is_cxl_port(struct device *dev);

struct cxl_port *to_cxl_port(struct device *dev);

struct cxl_port *devm_cxl_add_port(struct device *host, struct device *uport,

				   resource_size_t component_reg_phys,
@@ -301,6 +302,7 @@ int cxl_add_dport(struct cxl_port *port, struct device *dport, int port_id, 


struct cxl_decoder *to_cxl_decoder(struct device *dev);

bool is_root_decoder(struct device *dev);

bool is_cxl_decoder(struct device *dev);

struct cxl_decoder *cxl_root_decoder_alloc(struct cxl_port *port,

					   unsigned int nr_targets);

struct cxl_decoder *cxl_switch_decoder_alloc(struct cxl_port *port,
@@ -353,4 +355,83 @@ struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_nvdimm *cxl_nvd); 
#ifndef __mock

#define __mock static

#endif



#ifdef CONFIG_PROVE_CXL_LOCKING

enum cxl_lock_class {

	CXL_ANON_LOCK,

	CXL_NVDIMM_LOCK,

	CXL_NVDIMM_BRIDGE_LOCK,

	CXL_PORT_LOCK,

	/*

	 * Be careful to add new lock classes here, CXL_PORT_LOCK is

	 * extended by the port depth, so a maximum CXL port topology

	 * depth would need to be defined first.

	 */

};



static inline void cxl_nested_lock(struct device *dev)

{

	if (is_cxl_port(dev)) {

		struct cxl_port *port = to_cxl_port(dev);



		mutex_lock_nested(&dev->lockdep_mutex,

				  CXL_PORT_LOCK + port->depth);

	} else if (is_cxl_decoder(dev)) {

		struct cxl_port *port = to_cxl_port(dev->parent);



		/*

		 * A decoder is the immediate child of a port, so set

		 * its lock class equal to other child device siblings.

		 */

		mutex_lock_nested(&dev->lockdep_mutex,

				  CXL_PORT_LOCK + port->depth + 1);

	} else if (is_cxl_nvdimm_bridge(dev))

		mutex_lock_nested(&dev->lockdep_mutex, CXL_NVDIMM_BRIDGE_LOCK);

	else if (is_cxl_nvdimm(dev))

		mutex_lock_nested(&dev->lockdep_mutex, CXL_NVDIMM_LOCK);

	else

		mutex_lock_nested(&dev->lockdep_mutex, CXL_ANON_LOCK);

}



static inline void cxl_nested_unlock(struct device *dev)

{

	mutex_unlock(&dev->lockdep_mutex);

}



static inline void cxl_device_lock(struct device *dev)

{

	/*

	 * For double lock errors the lockup will happen before lockdep

	 * warns at cxl_nested_lock(), so assert explicitly.

	 */

	lockdep_assert_not_held(&dev->lockdep_mutex);



	device_lock(dev);

	cxl_nested_lock(dev);

}



static inline void cxl_device_unlock(struct device *dev)

{

	cxl_nested_unlock(dev);

	device_unlock(dev);

}

#else

static inline void cxl_nested_lock(struct device *dev)

{

}



static inline void cxl_nested_unlock(struct device *dev)

{

}



static inline void cxl_device_lock(struct device *dev)

{

	device_lock(dev);

}



static inline void cxl_device_unlock(struct device *dev)

{

	device_unlock(dev);

}

#endif

#endif /* __CXL_H__ */

drivers/cxl/pmem.c

+6 −6
Original line number Diff line number Diff line
@@ -43,7 +43,7 @@ static int cxl_nvdimm_probe(struct device *dev) 
	if (!cxl_nvb)

		return -ENXIO;



	device_lock(&cxl_nvb->dev);

	cxl_device_lock(&cxl_nvb->dev);

	if (!cxl_nvb->nvdimm_bus) {

		rc = -ENXIO;

		goto out;
@@ -68,7 +68,7 @@ static int cxl_nvdimm_probe(struct device *dev) 
	dev_set_drvdata(dev, nvdimm);

	rc = devm_add_action_or_reset(dev, unregister_nvdimm, nvdimm);

out:

	device_unlock(&cxl_nvb->dev);

	cxl_device_unlock(&cxl_nvb->dev);

	put_device(&cxl_nvb->dev);



	return rc;
@@ -233,7 +233,7 @@ static void cxl_nvb_update_state(struct work_struct *work) 
	struct nvdimm_bus *victim_bus = NULL;

	bool release = false, rescan = false;



	device_lock(&cxl_nvb->dev);

	cxl_device_lock(&cxl_nvb->dev);

	switch (cxl_nvb->state) {

	case CXL_NVB_ONLINE:

		if (!online_nvdimm_bus(cxl_nvb)) {
@@ -251,7 +251,7 @@ static void cxl_nvb_update_state(struct work_struct *work) 
	default:

		break;

	}

	device_unlock(&cxl_nvb->dev);

	cxl_device_unlock(&cxl_nvb->dev);



	if (release)

		device_release_driver(&cxl_nvb->dev);
@@ -327,9 +327,9 @@ static int cxl_nvdimm_bridge_reset(struct device *dev, void *data) 
		return 0;



	cxl_nvb = to_cxl_nvdimm_bridge(dev);

	device_lock(dev);

	cxl_device_lock(dev);

	cxl_nvb->state = CXL_NVB_NEW;

	device_unlock(dev);

	cxl_device_unlock(dev);



	return 0;

}