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Revision 1ab5ecb90cb6a3df1476e052f76a6e8f6511cb3d authored by Stanislav Kinsbursky on 12 March 2012, 02:59:41 UTC, committed by David S. Miller on 13 March 2012, 00:14:00 UTC 
tun: don't hold network namespace by tun sockets
 
v3: added previously removed sock_put() to the tun_release() callback, because
sk_release_kernel() doesn't drop the socket reference.

v2: sk_release_kernel() used for socket release. Dummy tun_release() is
required for sk_release_kernel() ---> sock_release() ---> sock->ops->release()
call.

TUN was designed to destroy it's socket on network namesapce shutdown. But this
will never happen for persistent device, because it's socket holds network
namespace.
This patch removes of holding network namespace by TUN socket and replaces it
by creating socket in init_net and then changing it's net it to desired one. On
shutdown socket is moved back to init_net prior to final put.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent de5c374
Raw File
mmu_context.c 
/* Copyright (C) 2009 Red Hat, Inc.
 *
 * See ../COPYING for licensing terms.
 */

#include <linux/mm.h>
#include <linux/mmu_context.h>
#include <linux/export.h>
#include <linux/sched.h>

#include <asm/mmu_context.h>

/*
 * use_mm
 *	Makes the calling kernel thread take on the specified
 *	mm context.
 *	Called by the retry thread execute retries within the
 *	iocb issuer's mm context, so that copy_from/to_user
 *	operations work seamlessly for aio.
 *	(Note: this routine is intended to be called only
 *	from a kernel thread context)
 */
void use_mm(struct mm_struct *mm)
{
	struct mm_struct *active_mm;
	struct task_struct *tsk = current;

	task_lock(tsk);
	active_mm = tsk->active_mm;
	if (active_mm != mm) {
		atomic_inc(&mm->mm_count);
		tsk->active_mm = mm;
	}
	tsk->mm = mm;
	switch_mm(active_mm, mm, tsk);
	task_unlock(tsk);

	if (active_mm != mm)
		mmdrop(active_mm);
}
EXPORT_SYMBOL_GPL(use_mm);

/*
 * unuse_mm
 *	Reverses the effect of use_mm, i.e. releases the
 *	specified mm context which was earlier taken on
 *	by the calling kernel thread
 *	(Note: this routine is intended to be called only
 *	from a kernel thread context)
 */
void unuse_mm(struct mm_struct *mm)
{
	struct task_struct *tsk = current;

	task_lock(tsk);
	sync_mm_rss(tsk, mm);
	tsk->mm = NULL;
	/* active_mm is still 'mm' */
	enter_lazy_tlb(mm, tsk);
	task_unlock(tsk);
}
EXPORT_SYMBOL_GPL(unuse_mm);
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