netdev - Re: [PATCH] proc: proc_create() should return true if CONFIG_PROC

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Date:	Thu, 26 Feb 2015 09:21:28 +0800
From:	Zhaolong Zhang <zhaolong.zhang@...driver.com>
To:	Jonathon Reinhart <jonathon.reinhart@...il.com>,
	David Howells <dhowells@...hat.com>
CC:	Zhang Zhaolong <zhangzl2013@....com>,
	"David S. Miller" <davem@...emloft.net>,
	Linux Netdev List <netdev@...r.kernel.org>,
	<viro@...iv.linux.org.uk>
Subject: Re: [PATCH] proc: proc_create() should return true if CONFIG_PROC_FS
 is not configured

On 02/26/2015 05:22 AM, Jonathon Reinhart wrote:
> On Wed, Feb 25, 2015 at 6:19 AM, David Howells<dhowells@...hat.com>  wrote:
>>> >>Does that even compile? proc_create() and proc_create_data() both return
>>> >>"struct proc_dir_entry *". It doesn't make sense for those macros to "return"
>>> >>anything but NULL - certainly not 1.
>>> >>
>>> >>Besides, why shouldn't "if (!proc_create())" behave like proc_create()
>>> >>failed when
>>> >>CONFIG_PROC_FS is not enabled?  You wouldn't want the caller to start trying
>>> >>to use that ((struct proc_dir_entry *)1) would you?
>> >
>> >It's sort of arguable.  If the proc interface is merely informational and
>> >doesn't impact the function of a module to not be present, then, yes, having
>> >proc_create() return some "true" value might make sense.  It's possible to
>> >arrange things so that all the proc-related functions and data get compiled
>> >out in such a situation by not being referenced by anything.
>> >
>> >However, if the proc interface isn't merely functional, then the proc_create()
>> >failure*is*  cause for module loading failure.  But in that case, there should
>> >be a Kconfig dependency on procfs and you should never use the dummy
>> >functions.
> Of the 528 calls to proc_create(_data), only 70 are in an "if (!proc_create())"
> style conditional. Another 188 assign the result to something, presumably a
> "struct proc_dir_entry *, which are going to fail compilation with this patch.

Oh, the usage of the CONFIG_PROC_FS macro should be checked wherever 
proc_create(_data) being called, right?
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