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Date: Fri, 22 Apr 2022 17:07:51 -0700
From: Ira Weiny <ira.weiny@...el.com>
To: Dan Williams <dan.j.williams@...el.com>
Cc: linux-cxl@...r.kernel.org,
Alison Schofield <alison.schofield@...el.com>,
Vishal Verma <vishal.l.verma@...el.com>,
Ben Widawsky <ben.widawsky@...el.com>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
peterz@...radead.org, nvdimm@...ts.linux.dev,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/8] cxl: Drop cxl_device_lock()
On Thu, Apr 21, 2022 at 08:33:23AM -0700, Dan Williams wrote:
> Now that all CXL subsystem locking is validated with custom lock
> classes, there is no need for the custom usage of the lockdep_mutex.
>
> 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>
Reviewed-by: Ira Weiny <ira.weiny@...el.com>
> ---
> drivers/cxl/core/pmem.c | 4 +-
> drivers/cxl/core/port.c | 55 ++++++++++++++-------------------
> drivers/cxl/cxl.h | 78 -----------------------------------------------
> drivers/cxl/mem.c | 4 +-
> drivers/cxl/pmem.c | 12 ++++---
> lib/Kconfig.debug | 6 ----
> 6 files changed, 33 insertions(+), 126 deletions(-)
>
> diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c
> index e825e261278d..bec7cfb54ebf 100644
> --- a/drivers/cxl/core/pmem.c
> +++ b/drivers/cxl/core/pmem.c
> @@ -124,10 +124,10 @@ 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.
> */
> - cxl_device_lock(&cxl_nvb->dev);
> + device_lock(&cxl_nvb->dev);
> flush = cxl_nvb->state != CXL_NVB_NEW;
> cxl_nvb->state = CXL_NVB_DEAD;
> - cxl_device_unlock(&cxl_nvb->dev);
> + 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 750aac95ed5f..ea60abda6500 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);
> }
> @@ -556,7 +556,7 @@ 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) {
> @@ -566,7 +566,7 @@ static int match_root_child(struct device *dev, const void *match)
> }
> }
> out:
> - cxl_device_unlock(dev);
> + device_unlock(dev);
>
> return !!iter;
> }
> @@ -625,13 +625,13 @@ 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)
> @@ -738,15 +738,15 @@ 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;
> }
> @@ -856,12 +856,12 @@ 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);
> @@ -922,7 +922,7 @@ 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
> @@ -930,12 +930,12 @@ 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));
> @@ -950,7 +950,7 @@ 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",
> @@ -958,7 +958,7 @@ 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);
> }
> }
>
> @@ -1006,7 +1006,7 @@ 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",
> @@ -1024,7 +1024,7 @@ 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);
> @@ -1135,14 +1135,14 @@ 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);
> @@ -1384,9 +1384,9 @@ 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;
> }
> @@ -1457,14 +1457,7 @@ static int cxl_bus_probe(struct device *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);
> -
> dev_dbg(dev, "probe: %d\n", rc);
> return rc;
> }
> @@ -1473,10 +1466,8 @@ 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);
> }
>
> static struct workqueue_struct *cxl_bus_wq;
> 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__ */
> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
> index 49a4b1c47299..91fb8d5b21a7 100644
> --- a/drivers/cxl/mem.c
> +++ b/drivers/cxl/mem.c
> @@ -195,7 +195,7 @@ static int cxl_mem_probe(struct device *dev)
> return -ENXIO;
> }
>
> - cxl_device_lock(&parent_port->dev);
> + device_lock(&parent_port->dev);
> if (!parent_port->dev.driver) {
> dev_err(dev, "CXL port topology %s not enabled\n",
> dev_name(&parent_port->dev));
> @@ -205,7 +205,7 @@ static int cxl_mem_probe(struct device *dev)
>
> rc = create_endpoint(cxlmd, parent_port);
> out:
> - cxl_device_unlock(&parent_port->dev);
> + device_unlock(&parent_port->dev);
> put_device(&parent_port->dev);
> return rc;
> }
> diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
> index 15ad666ab03e..b65a272a2d6d 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;
>
> - cxl_device_lock(&cxl_nvb->dev);
> + 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:
> - cxl_device_unlock(&cxl_nvb->dev);
> + 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;
>
> - cxl_device_lock(&cxl_nvb->dev);
> + 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;
> }
> - cxl_device_unlock(&cxl_nvb->dev);
> + 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);
> - cxl_device_lock(dev);
> + device_lock(dev);
> cxl_nvb->state = CXL_NVB_NEW;
> - cxl_device_unlock(dev);
> + device_unlock(dev);
>
> return 0;
> }
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 075cd25363ac..4a2c853c948b 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -1559,12 +1559,6 @@ config PROVE_NVDIMM_LOCKING
> 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
>
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