linux-kernel - Re: [PATCH] driver core: Add a guard() definition for the device

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Date:   Thu, 14 Dec 2023 16:33:47 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Vishal Verma <vishal.l.verma@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-cxl@...r.kernel.org,
        nvdimm@...ts.linux.dev
Subject: Re: [PATCH] driver core: Add a guard() definition for the
 device_lock()

On Wed, Dec 13, 2023 at 03:02:35PM -0800, Dan Williams wrote:
> At present there are ~200 usages of device_lock() in the kernel. Some of
> those usages lead to "goto unlock;" patterns which have proven to be
> error prone. Define a "device" guard() definition to allow for those to
> be cleaned up and prevent new ones from appearing.
> 
> Link: http://lore.kernel.org/r/657897453dda8_269bd29492@dwillia2-mobl3.amr.corp.intel.com.notmuch
> Link: http://lore.kernel.org/r/6577b0c2a02df_a04c5294bb@dwillia2-xfh.jf.intel.com.notmuch
> Cc: Vishal Verma <vishal.l.verma@...el.com>
> Cc: Ira Weiny <ira.weiny@...el.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
> Hi Greg,
> 
> I wonder if you might include this change in v6.7-rc to ease some patch
> sets alternately going through my tree and Andrew's tree. Those
> discussions are linked above. Alternately I can can just take it through
> my tree with your ack and the other use case can circle back to it in
> the v6.9 cycle.

Sure, I'll queue it up now for 6.7-final, makes sense to have it now for
others to build off of, and for me to fix up some places in the driver
core to use it as well.

> I considered also defining a __free() helper similar to __free(mutex),
> but I think "__free(device)" would be a surprising name for something
> that drops a lock. Also, I like the syntax of guard(device) over
> something like guard(device_lock) since a 'struct device *' is the
> argument, not a lock type, but I'm open to your or Peter's thoughts on
> the naming.

guard(device); makes sense to me, as that's what you are doing here, so
I'm good with it.

thanks,

greg k-h