cxl: Replace lockdep_mutex with local lock classes

In response to an attempt to expand dev->lockdep_mutex for device_lock()
validation [1], Peter points out [2] that the lockdep API already has
the ability to assign a dedicated lock class per subsystem device-type.

Use lockdep_set_class() to override the default device_lock()
'__lockdep_no_validate__' class for each CXL subsystem device-type. This
enables lockdep to detect deadlocks and recursive locking within the
device-driver core and the subsystem. The
lockdep_set_class_and_subclass() API is used for port objects that
recursively lock the 'cxl_port_key' class by hierarchical topology
depth.

Link: https://lore.kernel.org/r/164982968798.684294.15817853329823976469.stgit@dwillia2-desk3.amr.corp.intel.com
Link: https://lore.kernel.org/r/Ylf0dewci8myLvoW@hirez.programming.kicks-ass.net
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Ben Widawsky <ben.widawsky@intel.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/165055519317.3745911.7342499516839702840.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 1f76b28f9826b0119ce57402cacb1cbc5a39d32c..f7cdcd33504aa5d800ba14fe37d30cb00af623c8 100644 (file)
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -228,6 +228,8 @@ static void detach_memdev(struct work_struct *work)
        put_device(&cxlmd->dev);
 }
 
+static struct lock_class_key cxl_memdev_key;
+
 static struct cxl_memdev *cxl_memdev_alloc(struct cxl_dev_state *cxlds,
                                           const struct file_operations *fops)
 {
@@ -247,6 +249,7 @@ static struct cxl_memdev *cxl_memdev_alloc(struct cxl_dev_state *cxlds,
 
        dev = &cxlmd->dev;
        device_initialize(dev);
+       lockdep_set_class(&dev->mutex, &cxl_memdev_key);
        dev->parent = cxlds->dev;
        dev->bus = &cxl_bus_type;
        dev->devt = MKDEV(cxl_mem_major, cxlmd->id);

diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c
index 8de240c4d96bba5a7559f95da375e7c74fda584f..e825e261278d880d5e49f6de501e5d56d12f7b85 100644 (file)
--- 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 struct 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;
@@ -99,6 +101,7 @@ static struct cxl_nvdimm_bridge *cxl_nvdimm_bridge_alloc(struct cxl_port *port)
        cxl_nvb->port = port;
        cxl_nvb->state = CXL_NVB_NEW;
        device_initialize(dev);
+       lockdep_set_class(&dev->mutex, &cxl_nvdimm_bridge_key);
        device_set_pm_not_required(dev);
        dev->parent = &port->dev;
        dev->bus = &cxl_bus_type;
@@ -214,6 +217,8 @@ 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;
@@ -226,6 +231,7 @@ static struct cxl_nvdimm *cxl_nvdimm_alloc(struct cxl_memdev *cxlmd)
        dev = &cxl_nvd->dev;
        cxl_nvd->cxlmd = cxlmd;
        device_initialize(dev);
+       lockdep_set_class(&dev->mutex, &cxl_nvdimm_key);
        device_set_pm_not_required(dev);
        dev->parent = &cxlmd->dev;
        dev->bus = &cxl_bus_type;

diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 2ab1ba4499b309f7e7097e4044cfb90eb415c380..750aac95ed5fd6b71d819c3a6a21d920c587ef15 100644 (file)
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -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)
@@ -415,9 +417,10 @@ static struct cxl_port *cxl_port_alloc(struct device *uport,
         * description.
         */
        dev = &port->dev;
-       if (parent_port)
+       if (parent_port) {
                dev->parent = &parent_port->dev;
-       else
+               port->depth = parent_port->depth + 1;
+       } else
                dev->parent = uport;
 
        port->uport = uport;
@@ -427,6 +430,7 @@ static struct cxl_port *cxl_port_alloc(struct device *uport,
        INIT_LIST_HEAD(&port->endpoints);
 
        device_initialize(dev);
+       lockdep_set_class_and_subclass(&dev->mutex, &cxl_port_key, port->depth);
        device_set_pm_not_required(dev);
        dev->bus = &cxl_bus_type;
        dev->type = &cxl_port_type;
@@ -457,8 +461,6 @@ struct cxl_port *devm_cxl_add_port(struct device *host, struct device *uport,
        if (IS_ERR(port))
                return port;
 
-       if (parent_port)
-               port->depth = parent_port->depth + 1;
        dev = &port->dev;
        if (is_cxl_memdev(uport))
                rc = dev_set_name(dev, "endpoint%d", port->id);
@@ -1173,6 +1175,8 @@ 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
@@ -1214,6 +1218,7 @@ static struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port,
        seqlock_init(&cxld->target_lock);
        dev = &cxld->dev;
        device_initialize(dev);
+       lockdep_set_class(&dev->mutex, &cxl_decoder_key);
        device_set_pm_not_required(dev);
        dev->parent = &port->dev;
        dev->bus = &cxl_bus_type;