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Message-ID: <165055519317.3745911.7342499516839702840.stgit@dwillia2-desk3.amr.corp.intel.com>
Date: Thu, 21 Apr 2022 08:33:13 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: linux-cxl@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
Waiman Long <longman@...hat.com>,
Boqun Feng <boqun.feng@...il.com>,
Alison Schofield <alison.schofield@...el.com>,
Vishal Verma <vishal.l.verma@...el.com>,
Ira Weiny <ira.weiny@...el.com>,
Ben Widawsky <ben.widawsky@...el.com>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
nvdimm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/8] 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 [1]
Link: https://lore.kernel.org/r/Ylf0dewci8myLvoW@hirez.programming.kicks-ass.net [2]
Suggested-by: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Will Deacon <will@...nel.org>
Cc: Waiman Long <longman@...hat.com>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Alison Schofield <alison.schofield@...el.com>
Cc: Vishal Verma <vishal.l.verma@...el.com>
Cc: Ira Weiny <ira.weiny@...el.com>
Cc: Ben Widawsky <ben.widawsky@...el.com>
Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.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;
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