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Date: Fri, 19 Apr 2024 15:32:04 +0800
From: Xu Yilun <yilun.xu@linux.intel.com>
To: Marco Pagani <marpagan@redhat.com>
Cc: Moritz Fischer <mdf@kernel.org>, Wu Hao <hao.wu@intel.com>,
	Xu Yilun <yilun.xu@intel.com>, Tom Rix <trix@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Alan Tull <atull@opensource.altera.com>,
	Russ Weight <russ.weight@linux.dev>, linux-fpga@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5] fpga: region: add owner module and take its refcount
Message-ID: <ZiId9CnGEjwMcXeX@yilunxu-OptiPlex-7050>
References: <20240411144811.121500-1-marpagan@redhat.com>
 <ZhnviXAgnTdzUyV4@yilunxu-OptiPlex-7050>
 <669b8b55-df83-4c32-9c8f-41895db18b75@redhat.com>
 <e5f15ea4-f8e4-4a97-95f6-63a2099d084c@redhat.com>
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In-Reply-To: <e5f15ea4-f8e4-4a97-95f6-63a2099d084c@redhat.com>

On Mon, Apr 15, 2024 at 07:11:03PM +0200, Marco Pagani wrote:
> On 2024-04-15 14:19, Marco Pagani wrote:
> > 
> > 
> > On 2024-04-13 04:35, Xu Yilun wrote:
> >>>  /**
> >>> - * fpga_region_register_full - create and register an FPGA Region device
> >>> + * __fpga_region_register_full - create and register an FPGA Region device
> >>>   * @parent: device parent
> >>>   * @info: parameters for FPGA Region
> >>> + * @owner: owner module containing the get_bridges function
> >>
> >> This is too specific and easily get unaligned if we add another
> >> callback. How about "module containing the region ops"?
> > 
> > I had some concerns about using the name "region ops" in the kernel-doc
> > comment since it was not supported by a struct definition nor referenced
> > in the documentation. However, since the name is now referred to in the
> > ops_owner pointer, making the change makes sense to me.
> > 
> 
> On second thought, I think it would be better to leave the @owner
> description to "module containing the get_bridges function" for the
> moment. Otherwise, it could confuse the user by blurring the connection
> between the @owner and @get_bridges parameters.
> 
> * __fpga_region_register - create and register an FPGA Region device
> * [...]
> * @get_bridges: optional function to get bridges to a list
> * @owner: owner module containing get_bridges function
> 
> We can always modify the @owner description later, together with all the
> necessary changes to add a new op, like grouping all ops in a structure
> and changing the registration function signature.

OK, it's good to me. I'll apply this patch to for-next.

Acked-by: Xu Yilun <yilun.xu@intel.com>

> 
> Thanks,
> Marco
> 
> > 
> >>
> >>>   *
> >>>   * Return: struct fpga_region or ERR_PTR()
> >>>   */
> >>>  struct fpga_region *
> >>> -fpga_region_register_full(struct device *parent, const struct fpga_region_info *info)
> >>> +__fpga_region_register_full(struct device *parent, const struct fpga_region_info *info,
> >>> +			    struct module *owner)
> >>>  {
> >>>  	struct fpga_region *region;
> >>>  	int id, ret = 0;
> >>> @@ -213,6 +215,7 @@ fpga_region_register_full(struct device *parent, const struct fpga_region_info *
> >>>  	region->compat_id = info->compat_id;
> >>>  	region->priv = info->priv;
> >>>  	region->get_bridges = info->get_bridges;
> >>> +	region->ops_owner = owner;
> >>>  
> >>>  	mutex_init(&region->mutex);
> >>>  	INIT_LIST_HEAD(&region->bridge_list);
> >>> @@ -241,13 +244,14 @@ fpga_region_register_full(struct device *parent, const struct fpga_region_info *
> >>>  
> >>>  	return ERR_PTR(ret);
> >>>  }
> >>> -EXPORT_SYMBOL_GPL(fpga_region_register_full);
> >>> +EXPORT_SYMBOL_GPL(__fpga_region_register_full);
> >>>  
> >>>  /**
> >>> - * fpga_region_register - create and register an FPGA Region device
> >>> + * __fpga_region_register - create and register an FPGA Region device
> >>>   * @parent: device parent
> >>>   * @mgr: manager that programs this region
> >>>   * @get_bridges: optional function to get bridges to a list
> >>> + * @owner: owner module containing get_bridges function
> >>
> >> ditto
> >>
> >>>   *
> >>>   * This simple version of the register function should be sufficient for most users.
> >>>   * The fpga_region_register_full() function is available for users that need to
> >>> @@ -256,17 +260,17 @@ EXPORT_SYMBOL_GPL(fpga_region_register_full);
> >>>   * Return: struct fpga_region or ERR_PTR()
> >>>   */
> >>>  struct fpga_region *
> >>> -fpga_region_register(struct device *parent, struct fpga_manager *mgr,
> >>> -		     int (*get_bridges)(struct fpga_region *))
> >>> +__fpga_region_register(struct device *parent, struct fpga_manager *mgr,
> >>> +		       int (*get_bridges)(struct fpga_region *), struct module *owner)
> >>>  {
> >>>  	struct fpga_region_info info = { 0 };
> >>>  
> >>>  	info.mgr = mgr;
> >>>  	info.get_bridges = get_bridges;
> >>>  
> >>> -	return fpga_region_register_full(parent, &info);
> >>> +	return __fpga_region_register_full(parent, &info, owner);
> >>>  }
> >>> -EXPORT_SYMBOL_GPL(fpga_region_register);
> >>> +EXPORT_SYMBOL_GPL(__fpga_region_register);
> >>>  
> >>>  /**
> >>>   * fpga_region_unregister - unregister an FPGA region
> >>> diff --git a/include/linux/fpga/fpga-region.h b/include/linux/fpga/fpga-region.h
> >>> index 9d4d32909340..5fbc05fe70a6 100644
> >>> --- a/include/linux/fpga/fpga-region.h
> >>> +++ b/include/linux/fpga/fpga-region.h
> >>> @@ -36,6 +36,7 @@ struct fpga_region_info {
> >>>   * @mgr: FPGA manager
> >>>   * @info: FPGA image info
> >>>   * @compat_id: FPGA region id for compatibility check.
> >>> + * @ops_owner: module containing the get_bridges function
> >>
> >> ditto
> >>
> >> Thanks,
> >> Yilun
> >>
> >>>   * @priv: private data
> >>>   * @get_bridges: optional function to get bridges to a list
> >>>   */
> >>> @@ -46,6 +47,7 @@ struct fpga_region {
> >>>  	struct fpga_manager *mgr;
> >>>  	struct fpga_image_info *info;
> >>>  	struct fpga_compat_id *compat_id;
> >>> +	struct module *ops_owner;
> >>>  	void *priv;
> >>>  	int (*get_bridges)(struct fpga_region *region);
> >>>  };
> >>
>