Re: [PATCH v4 11/21] cxl/mbox: Move mailbox and other non-PCI specific infrastructure to the core

From: Dan Williams <dan.j.williams@intel.com>
To: Ben Widawsky <ben.widawsky@intel.com>
Cc: linux-cxl@vger.kernel.org, kernel test robot <lkp@intel.com>,
	 Vishal L Verma <vishal.l.verma@intel.com>,
	Linux NVDIMM <nvdimm@lists.linux.dev>,
	 "Schofield, Alison" <alison.schofield@intel.com>,
	"Weiny, Ira" <ira.weiny@intel.com>,
	 Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: Re: [PATCH v4 11/21] cxl/mbox: Move mailbox and other non-PCI specific infrastructure to the core
Date: Thu, 9 Sep 2021 11:50:01 -0700	[thread overview]
Message-ID: <CAPcyv4hH7=cbnpz9dcKFEByqZkVxJVXpuks4g_63VguisDdPPw@mail.gmail.com> (raw)
In-Reply-To: <20210909164125.ttvptq6eiiirvnnp@intel.com>

On Thu, Sep 9, 2021 at 9:41 AM Ben Widawsky <ben.widawsky@intel.com> wrote:
>
> On 21-09-08 22:12:32, Dan Williams wrote:
> > Now that the internals of mailbox operations are abstracted from the PCI
> > specifics a bulk of infrastructure can move to the core.
> >
> > The CXL_PMEM driver intends to proxy LIBNVDIMM UAPI and driver requests
> > to the equivalent functionality provided by the CXL hardware mailbox
> > interface. In support of that intent move the mailbox implementation to
> > a shared location for the CXL_PCI driver native IOCTL path and CXL_PMEM
> > nvdimm command proxy path to share.
> >
> > A unit test framework seeks to implement a unit test backend transport
> > for mailbox commands to communicate mocked up payloads. It can reuse all
> > of the mailbox infrastructure minus the PCI specifics, so that also gets
> > moved to the core.
> >
> > Finally with the mailbox infrastructure and ioctl handling being
> > transport generic there is no longer any need to pass file
> > file_operations to devm_cxl_add_memdev(). That allows all the ioctl
> > boilerplate to move into the core for unit test reuse.
> >
> > No functional change intended, just code movement.
>
> At some point, I think some of the comments and kernel docs need updating since
> the target is no longer exclusively memory devices. Perhaps you do this in later
> patches....

I would wait to rework comments when/if it becomes clear that a
non-memory-device driver wants to reuse the mailbox core. I do not see
any indications that the comments are currently broken, do you?

[..]
> > diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> > index 036a3c8106b4..c85b7fbad02d 100644
> > --- a/drivers/cxl/core/core.h
> > +++ b/drivers/cxl/core/core.h
> > @@ -14,7 +14,15 @@ static inline void unregister_cxl_dev(void *dev)
> >       device_unregister(dev);
> >  }
> >
> > +struct cxl_send_command;
> > +struct cxl_mem_query_commands;
> > +int cxl_query_cmd(struct cxl_memdev *cxlmd,
> > +               struct cxl_mem_query_commands __user *q);
> > +int cxl_send_cmd(struct cxl_memdev *cxlmd, struct cxl_send_command __user *s);
> > +
> >  int cxl_memdev_init(void);
> >  void cxl_memdev_exit(void);
> > +void cxl_mbox_init(void);
> > +void cxl_mbox_exit(void);
>
> cxl_mbox_fini()?

The idiomatic kernel module shutdown function is suffixed _exit().

[..]