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: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
Changes since v3:
- Add comment about adding new lock classes after CXL_PORT_LOCK
(Jonathan)
- Comment why cxl_bus_probe() needs to take cxl_nested_lock() directly
(Jonathan)
- Fixup some whitespace (Jonathan)
drivers/cxl/acpi.c | 10 +++---
drivers/cxl/core/pmem.c | 4 +-
drivers/cxl/core/port.c | 47 ++++++++++++++++++++-------
drivers/cxl/cxl.h | 81 ++++++++++++++++++++++++++++++++++++++++++++++
drivers/cxl/pmem.c | 12 +++----
drivers/nvdimm/nd-core.h | 2 +
lib/Kconfig.debug | 23 +++++++++++++
7 files changed, 154 insertions(+), 25 deletions(-)
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 4e8086525edc..93d1dc56892a 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -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;
diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c
index b5fca97b0a07..40b3f5030496 100644
--- a/drivers/cxl/core/pmem.c
+++ b/drivers/cxl/core/pmem.c
@@ -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()
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 4ec5febf73fb..35d1afd63aee 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -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;
}
@@ -712,15 +725,27 @@ 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 = {
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index c1dc53492773..1c9d10e92ea3 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -285,6 +285,7 @@ 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,
@@ -295,6 +296,7 @@ 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,
@@ -347,4 +349,83 @@ 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__ */
diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
index b65a272a2d6d..15ad666ab03e 100644
--- a/drivers/cxl/pmem.c
+++ b/drivers/cxl/pmem.c
@@ -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;
}
diff --git a/drivers/nvdimm/nd-core.h b/drivers/nvdimm/nd-core.h
index a11850dd475d..2650a852eeaf 100644
--- a/drivers/nvdimm/nd-core.h
+++ b/drivers/nvdimm/nd-core.h
@@ -185,7 +185,7 @@ static inline void devm_nsio_disable(struct device *dev,
}
#endif
-#ifdef CONFIG_PROVE_LOCKING
+#ifdef CONFIG_PROVE_NVDIMM_LOCKING
extern struct class *nd_class;
enum {
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 14b89aa37c5c..7dea203964f7 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1516,6 +1516,29 @@ config CSD_LOCK_WAIT_DEBUG
include the IPI handler function currently executing (if any)
and relevant stack traces.
+choice
+ prompt "Lock debugging: prove subsystem device_lock() correctness"
+ depends on PROVE_LOCKING
+ help
+ For subsystems that have instrumented their usage of the device_lock()
+ with nested annotations, enable lock dependency checking. The locking
+ hierarchy 'subclass' identifiers are not compatible across
+ sub-systems, so only one can be enabled at a time.
+
+config PROVE_NVDIMM_LOCKING
+ bool "NVDIMM"
+ depends on LIBNVDIMM
+ help
+ Enable lockdep to validate nd_device_lock() usage.
+
+config PROVE_CXL_LOCKING
+ bool "CXL"
+ depends on CXL_BUS
+ help
+ Enable lockdep to validate cxl_device_lock() usage.
+
+endchoice
+
endmenu # lock debugging
config TRACE_IRQFLAGS
