From mboxrd@z Thu Jan  1 00:00:00 1970
From: Boaz Harrosh <bharrosh@panasas.com>
Subject: Re: [PATCH v2] remove no longer use of pdflush interface
Date: Wed, 6 Jun 2012 10:31:12 +0300
Message-ID: <4FCF0740.1040204@panasas.com>
References: <1338888372-3555-1-git-send-email-liwp.linux@gmail.com> <20120605152845.8b633881.akpm@linux-foundation.org>
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Cc: Wanpeng Li <liwp.linux@gmail.com>,
	Fengguang Wu <fengguang.wu@intel.com>,
	Rob Landley <rob@landley.net>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Lucas De Marchi <lucas.demarchi@profusion.mobi>,
	"David S. Miller" <davem@davemloft.net>, Jan Kara <jack@suse.cz>,
	Mel Gorman <mgorman@suse.de>,
	Minchan Kim <minchan.kim@gmail.com>,
	David Howells <dhowells@redhat.com>,
	James Morris <james.l.morris@oracle.com>,
	Ingo Molnar <mingo@elte.hu>,
	Michel Lespinasse <walken@google.com>,
	<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-fsdevel@vger.kernel.org>,
	Gavin Shan <shangw@linux.vnet.ibm.com>,
	Wanpeng Li <liwp@linux.vnet.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
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On 06/06/2012 01:28 AM, Andrew Morton wrote:

> On Tue,  5 Jun 2012 17:26:11 +0800
> Wanpeng Li <liwp.linux@gmail.com> wrote:
> 
> So perhaps the solution is to give up on the generic proc_obsolete()
> idea, and just add a handler specifically for nr_pdflush_threads, whcih
> uses printk_once().
> 


If there are many users than a self made print once is worth it
we can use the ctl_table->data pointer for this, some thing like:

int nr_pdflush_was_printed;

@@ -1095,11 +1095,9 @@ static struct ctl_table vm_table[] = {
 		.extra1		= &zero,
 	},
 	{
-		.procname	= "nr_pdflush_threads",
-		.data		= &nr_pdflush_threads,
-		.maxlen		= sizeof nr_pdflush_threads,
-		.mode		= 0444 /* read-only*/,
-		.proc_handler	= proc_dointvec,
+		.data		= &nr_pdflush_was_printed,
+		.procname       = "nr_pdflush_threads",
+		.mode           = 0444 /* read-only */,
+		.proc_handler   = proc_obsolete,
 	},


+/* notice associated proc deprecated */
+int proc_deprecated(struct ctl_table *table, int write,
+		    void __user *buffer, size_t *lenp, loff_t *ppos, )
+{
+	if (*ctl_table->data) {
+		printk(KERN_WARNING "%s exported in /proc is deprecated\n",
+			table->procname);
+		*ctl_table->data = 0;
+	}
+	return -ENOSYS;
+}