Re: [PATCH v2 03/12] cxl/core: Refactor a cxl_lock_class() out of cxl_nested_lock()

From: Peter Zijlstra
Date: Wed Apr 13 2022 - 05:40:19 EST

Next message: Cosmin Tanislav: "[PATCH v1 1/3] dt-bindings: iio: adc: add AD4130"
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In reply to: Dan Williams: "[PATCH v2 03/12] cxl/core: Refactor a cxl_lock_class() out of cxl_nested_lock()"
Next in thread: Dan Williams: "Re: [PATCH v2 03/12] cxl/core: Refactor a cxl_lock_class() out of cxl_nested_lock()"
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*Completely* untested (I wouldn't know where to begin and probably odn't
have the hardware anyway), and known incomplete.

What's wrong with something like this then?

---
drivers/cxl/core/pmem.c | 8 +++++
drivers/cxl/core/port.c | 58 +++++++++++++++++++++---------------
drivers/cxl/cxl.h | 78 -------------------------------------------------
3 files changed, 42 insertions(+), 102 deletions(-)

diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c
index 8de240c4d96b..aca0dd5eefeb 100644
--- a/drivers/cxl/core/pmem.c
+++ b/drivers/cxl/core/pmem.c
@@ -80,6 +80,8 @@ struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_nvdimm *cxl_nvd)
}
EXPORT_SYMBOL_NS_GPL(cxl_find_nvdimm_bridge, CXL);

+static lock_class_key cxl_nvdimm_bridge_key;
+
static struct cxl_nvdimm_bridge *cxl_nvdimm_bridge_alloc(struct cxl_port *port)
{
struct cxl_nvdimm_bridge *cxl_nvb;
@@ -104,6 +106,8 @@ static struct cxl_nvdimm_bridge *cxl_nvdimm_bridge_alloc(struct cxl_port *port)
dev->bus = &cxl_bus_type;
dev->type = &cxl_nvdimm_bridge_type;

+ lockdep_set_class(&dev->mutex, &cxl_nvdimm_bridge_key);
+
return cxl_nvb;

err:
@@ -214,6 +218,8 @@ struct cxl_nvdimm *to_cxl_nvdimm(struct device *dev)
}
EXPORT_SYMBOL_NS_GPL(to_cxl_nvdimm, CXL);

+static struct lock_class_key cxl_nvdimm_key;
+
static struct cxl_nvdimm *cxl_nvdimm_alloc(struct cxl_memdev *cxlmd)
{
struct cxl_nvdimm *cxl_nvd;
@@ -231,6 +237,8 @@ static struct cxl_nvdimm *cxl_nvdimm_alloc(struct cxl_memdev *cxlmd)
dev->bus = &cxl_bus_type;
dev->type = &cxl_nvdimm_type;

+ lockdep_set_class(&dev->mutex, &cxl_nvdimm_key);
+
return cxl_nvd;
}

diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 2ab1ba4499b3..cae88404612f 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -312,10 +312,10 @@ static void cxl_port_release(struct device *dev)
struct cxl_port *port = to_cxl_port(dev);
struct cxl_ep *ep, *_e;

- cxl_device_lock(dev);
+ device_lock(dev);
list_for_each_entry_safe(ep, _e, &port->endpoints, list)
cxl_ep_release(ep);
- cxl_device_unlock(dev);
+ device_unlock(dev);
ida_free(&cxl_port_ida, port->id);
kfree(port);
}
@@ -391,6 +391,8 @@ static int devm_cxl_link_uport(struct device *host, struct cxl_port *port)
return devm_add_action_or_reset(host, cxl_unlink_uport, port);
}

+static struct lock_class_key cxl_port_key;
+
static struct cxl_port *cxl_port_alloc(struct device *uport,
resource_size_t component_reg_phys,
struct cxl_port *parent_port)
@@ -431,6 +433,8 @@ static struct cxl_port *cxl_port_alloc(struct device *uport,
dev->bus = &cxl_bus_type;
dev->type = &cxl_port_type;

+ lockdep_set_class(&dev->mutex, &cxl_port_key);
+
return port;

err:
@@ -457,8 +461,10 @@ struct cxl_port *devm_cxl_add_port(struct device *host, struct device *uport,
if (IS_ERR(port))
return port;

- if (parent_port)
+ if (parent_port) {
port->depth = parent_port->depth + 1;
+ lockdep_set_class_and_subclass(&port->dev->mutex, &cxl_port, port->depth);
+ }
dev = &port->dev;
if (is_cxl_memdev(uport))
rc = dev_set_name(dev, "endpoint%d", port->id);
@@ -554,7 +560,7 @@ static int match_root_child(struct device *dev, const void *match)
return 0;

port = to_cxl_port(dev);
- cxl_device_lock(dev);
+ device_lock(dev);
list_for_each_entry(dport, &port->dports, list) {
iter = match;
while (iter) {
@@ -564,7 +570,7 @@ static int match_root_child(struct device *dev, const void *match)
}
}
out:
- cxl_device_unlock(dev);
+ device_unlock(dev);

return !!iter;
}
@@ -623,13 +629,13 @@ static int add_dport(struct cxl_port *port, struct cxl_dport *new)
static void cond_cxl_root_lock(struct cxl_port *port)
{
if (is_cxl_root(port))
- cxl_device_lock(&port->dev);
+ device_lock(&port->dev);
}

static void cond_cxl_root_unlock(struct cxl_port *port)
{
if (is_cxl_root(port))
- cxl_device_unlock(&port->dev);
+ device_unlock(&port->dev);
}

static void cxl_dport_remove(void *data)
@@ -736,15 +742,15 @@ static int add_ep(struct cxl_port *port, struct cxl_ep *new)
{
struct cxl_ep *dup;

- cxl_device_lock(&port->dev);
+ device_lock(&port->dev);
if (port->dead) {
- cxl_device_unlock(&port->dev);
+ device_unlock(&port->dev);
return -ENXIO;
}
dup = find_ep(port, new->ep);
if (!dup)
list_add_tail(&new->list, &port->endpoints);
- cxl_device_unlock(&port->dev);
+ device_unlock(&port->dev);

return dup ? -EEXIST : 0;
}
@@ -854,12 +860,12 @@ static void delete_endpoint(void *data)
goto out;
parent = &parent_port->dev;

- cxl_device_lock(parent);
+ device_lock(parent);
if (parent->driver && endpoint->uport) {
devm_release_action(parent, cxl_unlink_uport, endpoint);
devm_release_action(parent, unregister_port, endpoint);
}
- cxl_device_unlock(parent);
+ device_unlock(parent);
put_device(parent);
out:
put_device(&endpoint->dev);
@@ -920,7 +926,7 @@ static void cxl_detach_ep(void *data)
}

parent_port = to_cxl_port(port->dev.parent);
- cxl_device_lock(&parent_port->dev);
+ device_lock(&parent_port->dev);
if (!parent_port->dev.driver) {
/*
* The bottom-up race to delete the port lost to a
@@ -928,12 +934,12 @@ static void cxl_detach_ep(void *data)
* parent_port ->remove() will have cleaned up all
* descendants.
*/
- cxl_device_unlock(&parent_port->dev);
+ device_unlock(&parent_port->dev);
put_device(&port->dev);
continue;
}

- cxl_device_lock(&port->dev);
+ device_lock(&port->dev);
ep = find_ep(port, &cxlmd->dev);
dev_dbg(&cxlmd->dev, "disconnect %s from %s\n",
ep ? dev_name(ep->ep) : "", dev_name(&port->dev));
@@ -948,7 +954,7 @@ static void cxl_detach_ep(void *data)
port->dead = true;
list_splice_init(&port->dports, &reap_dports);
}
- cxl_device_unlock(&port->dev);
+ device_unlock(&port->dev);

if (!list_empty(&reap_dports)) {
dev_dbg(&cxlmd->dev, "delete %s\n",
@@ -956,7 +962,7 @@ static void cxl_detach_ep(void *data)
delete_switch_port(port, &reap_dports);
}
put_device(&port->dev);
- cxl_device_unlock(&parent_port->dev);
+ device_unlock(&parent_port->dev);
}
}

@@ -1004,7 +1010,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
return -EAGAIN;
}

- cxl_device_lock(&parent_port->dev);
+ device_lock(&parent_port->dev);
if (!parent_port->dev.driver) {
dev_warn(&cxlmd->dev,
"port %s:%s disabled, failed to enumerate CXL.mem\n",
@@ -1022,7 +1028,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
get_device(&port->dev);
}
out:
- cxl_device_unlock(&parent_port->dev);
+ device_unlock(&parent_port->dev);

if (IS_ERR(port))
rc = PTR_ERR(port);
@@ -1133,14 +1139,14 @@ struct cxl_dport *cxl_find_dport_by_dev(struct cxl_port *port,
{
struct cxl_dport *dport;

- cxl_device_lock(&port->dev);
+ device_lock(&port->dev);
list_for_each_entry(dport, &port->dports, list)
if (dport->dport == dev) {
- cxl_device_unlock(&port->dev);
+ device_unlock(&port->dev);
return dport;
}

- cxl_device_unlock(&port->dev);
+ device_unlock(&port->dev);
return NULL;
}
EXPORT_SYMBOL_NS_GPL(cxl_find_dport_by_dev, CXL);
@@ -1173,6 +1179,8 @@ static int decoder_populate_targets(struct cxl_decoder *cxld,
return rc;
}

+static struct lock_class_key cxl_decoder_key;
+
/**
* cxl_decoder_alloc - Allocate a new CXL decoder
* @port: owning port of this decoder
@@ -1224,6 +1232,8 @@ static struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port,
else
cxld->dev.type = &cxl_decoder_switch_type;

+ lockdep_set_class(&dev->mutex, cxl_decoder_key);
+
/* Pre initialize an "empty" decoder */
cxld->interleave_ways = 1;
cxld->interleave_granularity = PAGE_SIZE;
@@ -1379,9 +1389,9 @@ int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map)

port = to_cxl_port(cxld->dev.parent);

- cxl_device_lock(&port->dev);
+ device_lock(&port->dev);
rc = cxl_decoder_add_locked(cxld, target_map);
- cxl_device_unlock(&port->dev);
+ device_unlock(&port->dev);

return rc;
}
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 990b6670222e..140dc3278cde 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -405,82 +405,4 @@ struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_nvdimm *cxl_nvd);
#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__ */

Next message: Cosmin Tanislav: "[PATCH v1 1/3] dt-bindings: iio: adc: add AD4130"
Previous message: Krzysztof Kozlowski: "Re: [PATCH] NFC: NULL out the dev->rfkill to prevent UAF"
In reply to: Dan Williams: "[PATCH v2 03/12] cxl/core: Refactor a cxl_lock_class() out of cxl_nested_lock()"
Next in thread: Dan Williams: "Re: [PATCH v2 03/12] cxl/core: Refactor a cxl_lock_class() out of cxl_nested_lock()"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]