linux-kernel - Re: [PATCH v3 7/8] device-core: Kill the lockdep

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Date:   Fri, 22 Apr 2022 17:25:10 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     linux-cxl@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        vishal.l.verma@...el.com, alison.schofield@...el.com,
        nvdimm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 7/8] device-core: Kill the lockdep_mutex

On Thu, Apr 21, 2022 at 08:33:45AM -0700, Dan Williams wrote:
> Per Peter [1], the lockdep API has native support for all the use cases
> lockdep_mutex was attempting to enable. Now that all lockdep_mutex users
> have been converted to those APIs, drop this lock.
> 
> Link: https://lore.kernel.org/r/Ylf0dewci8myLvoW@hirez.programming.kicks-ass.net [1]
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>
> Suggested-by: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>

Reviewed-by: Ira Weiny <ira.weiny@...el.com>

> ---
>  drivers/base/core.c    |    3 ---
>  include/linux/device.h |    5 -----
>  2 files changed, 8 deletions(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 3d6430eb0c6a..2eede2ec3d64 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -2864,9 +2864,6 @@ void device_initialize(struct device *dev)
>  	kobject_init(&dev->kobj, &device_ktype);
>  	INIT_LIST_HEAD(&dev->dma_pools);
>  	mutex_init(&dev->mutex);
> -#ifdef CONFIG_PROVE_LOCKING
> -	mutex_init(&dev->lockdep_mutex);
> -#endif
>  	lockdep_set_novalidate_class(&dev->mutex);
>  	spin_lock_init(&dev->devres_lock);
>  	INIT_LIST_HEAD(&dev->devres_head);
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 82c9d307e7bd..c00ab223da50 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -400,8 +400,6 @@ struct dev_msi_info {
>   * 		This identifies the device type and carries type-specific
>   * 		information.
>   * @mutex:	Mutex to synchronize calls to its driver.
> - * @lockdep_mutex: An optional debug lock that a subsystem can use as a
> - * 		peer lock to gain localized lockdep coverage of the device_lock.
>   * @bus:	Type of bus device is on.
>   * @driver:	Which driver has allocated this
>   * @platform_data: Platform data specific to the device.
> @@ -499,9 +497,6 @@ struct device {
>  					   core doesn't touch it */
>  	void		*driver_data;	/* Driver data, set and get with
>  					   dev_set_drvdata/dev_get_drvdata */
> -#ifdef CONFIG_PROVE_LOCKING
> -	struct mutex		lockdep_mutex;
> -#endif
>  	struct mutex		mutex;	/* mutex to synchronize calls to
>  					 * its driver.
>  					 */
> 
>