aha/drivers/isdn/i4l/isdn_net.h
Xiaotian Feng 2bd9af046f isdn: fix possible circular locking dependency
There's a circular locking dependency:

---> isdn_net_get_locked_lp
    --->lock &nd->queue_lock
    --->lock &nd->queue->xmit_lock
    .....................
    ---->unlock &nd->queue_lock

---> isdn_net_writebuf_skb (called with &nd->queue->xmit_lock locked)
    ---->isdn_net_inc_frame_cnt
         ---->isdn_net_device_busy
              ----> lock &nd->queue_lock

This will trigger lockdep warnings:

 =======================================================
 [ INFO: possible circular locking dependency detected ]
 2.6.32-rc4-testing #7
 -------------------------------------------------------
 ipppd/28379 is trying to acquire lock:
 (&netdev->queue_lock){......}, at: [<e62ad0fd>] isdn_net_device_busy+0x2c/0x74 [isdn]

 but task is already holding lock:
 (&netdev->local->xmit_lock){+.....}, at: [<e62aefc2>] isdn_net_write_super+0x3f/0x6e [isdn]

 which lock already depends on the new lock.
 .......

 We don't need to lock nd->queue->xmit_lock to protect single
isdn_net_lp_busy(). This can fix above lockdep warnings.

Reported-and-tested-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Xiaotian Feng <xtfeng@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2009-10-22 18:27:53 -07:00

152 lines
4.9 KiB
C

/* $Id: isdn_net.h,v 1.1.2.2 2004/01/12 22:37:19 keil Exp $
*
* header for Linux ISDN subsystem, network related functions (linklevel).
*
* Copyright 1994-1999 by Fritz Elfert (fritz@isdn4linux.de)
* Copyright 1995,96 by Thinking Objects Software GmbH Wuerzburg
* Copyright 1995,96 by Michael Hipp (Michael.Hipp@student.uni-tuebingen.de)
*
* This software may be used and distributed according to the terms
* of the GNU General Public License, incorporated herein by reference.
*
*/
/* Definitions for hupflags: */
#define ISDN_WAITCHARGE 1 /* did not get a charge info yet */
#define ISDN_HAVECHARGE 2 /* We know a charge info */
#define ISDN_CHARGEHUP 4 /* We want to use the charge mechanism */
#define ISDN_INHUP 8 /* Even if incoming, close after huptimeout */
#define ISDN_MANCHARGE 16 /* Charge Interval manually set */
/*
* Definitions for Cisco-HDLC header.
*/
#define CISCO_ADDR_UNICAST 0x0f
#define CISCO_ADDR_BROADCAST 0x8f
#define CISCO_CTRL 0x00
#define CISCO_TYPE_CDP 0x2000
#define CISCO_TYPE_SLARP 0x8035
#define CISCO_SLARP_REQUEST 0
#define CISCO_SLARP_REPLY 1
#define CISCO_SLARP_KEEPALIVE 2
extern char *isdn_net_new(char *, struct net_device *);
extern char *isdn_net_newslave(char *);
extern int isdn_net_rm(char *);
extern int isdn_net_rmall(void);
extern int isdn_net_stat_callback(int, isdn_ctrl *);
extern int isdn_net_setcfg(isdn_net_ioctl_cfg *);
extern int isdn_net_getcfg(isdn_net_ioctl_cfg *);
extern int isdn_net_addphone(isdn_net_ioctl_phone *);
extern int isdn_net_getphones(isdn_net_ioctl_phone *, char __user *);
extern int isdn_net_getpeer(isdn_net_ioctl_phone *, isdn_net_ioctl_phone __user *);
extern int isdn_net_delphone(isdn_net_ioctl_phone *);
extern int isdn_net_find_icall(int, int, int, setup_parm *);
extern void isdn_net_hangup(struct net_device *);
extern void isdn_net_dial(void);
extern void isdn_net_autohup(void);
extern int isdn_net_force_hangup(char *);
extern int isdn_net_force_dial(char *);
extern isdn_net_dev *isdn_net_findif(char *);
extern int isdn_net_rcv_skb(int, struct sk_buff *);
extern int isdn_net_dial_req(isdn_net_local *);
extern void isdn_net_writebuf_skb(isdn_net_local *lp, struct sk_buff *skb);
extern void isdn_net_write_super(isdn_net_local *lp, struct sk_buff *skb);
#define ISDN_NET_MAX_QUEUE_LENGTH 2
#define ISDN_MASTER_PRIV(lp) ((isdn_net_local *) netdev_priv(lp->master))
#define ISDN_SLAVE_PRIV(lp) ((isdn_net_local *) netdev_priv(lp->slave))
#define MASTER_TO_SLAVE(master) \
(((isdn_net_local *) netdev_priv(master))->slave)
/*
* is this particular channel busy?
*/
static __inline__ int isdn_net_lp_busy(isdn_net_local *lp)
{
if (atomic_read(&lp->frame_cnt) < ISDN_NET_MAX_QUEUE_LENGTH)
return 0;
else
return 1;
}
/*
* For the given net device, this will get a non-busy channel out of the
* corresponding bundle. The returned channel is locked.
*/
static __inline__ isdn_net_local * isdn_net_get_locked_lp(isdn_net_dev *nd)
{
unsigned long flags;
isdn_net_local *lp;
spin_lock_irqsave(&nd->queue_lock, flags);
lp = nd->queue; /* get lp on top of queue */
while (isdn_net_lp_busy(nd->queue)) {
nd->queue = nd->queue->next;
if (nd->queue == lp) { /* not found -- should never happen */
lp = NULL;
goto errout;
}
}
lp = nd->queue;
nd->queue = nd->queue->next;
spin_unlock_irqrestore(&nd->queue_lock, flags);
spin_lock(&lp->xmit_lock);
local_bh_disable();
return lp;
errout:
spin_unlock_irqrestore(&nd->queue_lock, flags);
return lp;
}
/*
* add a channel to a bundle
*/
static __inline__ void isdn_net_add_to_bundle(isdn_net_dev *nd, isdn_net_local *nlp)
{
isdn_net_local *lp;
unsigned long flags;
spin_lock_irqsave(&nd->queue_lock, flags);
lp = nd->queue;
// printk(KERN_DEBUG "%s: lp:%s(%p) nlp:%s(%p) last(%p)\n",
// __func__, lp->name, lp, nlp->name, nlp, lp->last);
nlp->last = lp->last;
lp->last->next = nlp;
lp->last = nlp;
nlp->next = lp;
nd->queue = nlp;
spin_unlock_irqrestore(&nd->queue_lock, flags);
}
/*
* remove a channel from the bundle it belongs to
*/
static __inline__ void isdn_net_rm_from_bundle(isdn_net_local *lp)
{
isdn_net_local *master_lp = lp;
unsigned long flags;
if (lp->master)
master_lp = ISDN_MASTER_PRIV(lp);
// printk(KERN_DEBUG "%s: lp:%s(%p) mlp:%s(%p) last(%p) next(%p) mndq(%p)\n",
// __func__, lp->name, lp, master_lp->name, master_lp, lp->last, lp->next, master_lp->netdev->queue);
spin_lock_irqsave(&master_lp->netdev->queue_lock, flags);
lp->last->next = lp->next;
lp->next->last = lp->last;
if (master_lp->netdev->queue == lp) {
master_lp->netdev->queue = lp->next;
if (lp->next == lp) { /* last in queue */
master_lp->netdev->queue = master_lp->netdev->local;
}
}
lp->next = lp->last = lp; /* (re)set own pointers */
// printk(KERN_DEBUG "%s: mndq(%p)\n",
// __func__, master_lp->netdev->queue);
spin_unlock_irqrestore(&master_lp->netdev->queue_lock, flags);
}