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.st...@dwillia2-desk3.amr.corp.intel.com [1] Link: https://lore.kernel.org/r/ylf0dewci8myl...@hirez.programming.kicks-ass.net [2] Suggested-by: Peter Zijlstra <pet...@infradead.org> Cc: Ingo Molnar <mi...@redhat.com> Cc: Will Deacon <w...@kernel.org> Cc: Waiman Long <long...@redhat.com> Cc: Boqun Feng <boqun.f...@gmail.com> Cc: Alison Schofield <alison.schofi...@intel.com> Cc: Vishal Verma <vishal.l.ve...@intel.com> Cc: Ira Weiny <ira.we...@intel.com> Cc: Ben Widawsky <ben.widaw...@intel.com> Cc: Jonathan Cameron <jonathan.came...@huawei.com> Signed-off-by: Dan Williams <dan.j.willi...@intel.com> --- drivers/cxl/core/memdev.c | 3 +++ drivers/cxl/core/pmem.c | 6 ++++++ drivers/cxl/core/port.c | 13 +++++++++---- 3 files changed, 18 insertions(+), 4 deletions(-) diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c index 1f76b28f9826..f7cdcd33504a 100644 --- 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 8de240c4d96b..e825e261278d 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 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 2ab1ba4499b3..750aac95ed5f 100644 --- 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;
