BUG: double spinlock in "drivers/net/3c505.c"

BUG: double spinlock in "drivers/net/3c505.c"

[Alexander Strakh]

	KERNEL_VERSION: 2.6.35-rc1
        SUBJECT: duble spinlock  in function elp_start_xmit
        SUBSCRIBE:
        In driver drivers/net/3c505.c in function elp_start_xmit:

1. In line 1075 we have first spinlock. In the next line we called 
check_3c505_dma:

1070 static netdev_tx_t elp_start_xmit(struct sk_buff *skb, struct net_device 
*dev)
1071 {
1072         unsigned long flags;
1073         elp_device *adapter = netdev_priv(dev);
1074
1075         spin_lock_irqsave(&adapter->lock, flags);
1076         check_3c505_dma(dev);

2. In function check_3c505_dma we have second spinloock at line 301.

 293 static inline void check_3c505_dma(struct net_device *dev)
 294 {
 295         elp_device *adapter = netdev_priv(dev);
 296         if (adapter->dmaing && time_after(jiffies, adapter-
>current_dma.start_time + 10)) {
 297                 unsigned long flags, f;
 298                 pr_err("%s: DMA %s timed out, %d bytes left\n", dev-
>name,
 299                         adapter->current_dma.direction ? "download" : 
"upload",
 300                         get_dma_residue(dev->dma));
 301                 spin_lock_irqsave(&adapter->lock, flags);


Found by Linux Device Drivers Verification Project (Svace Detector)

Re: BUG: double spinlock in "drivers/net/3c505.c"

[Christoph Fritz]

On Mon, 2010-06-07 at 15:17 +0400, Alexander Strakh wrote: 
> 	KERNEL_VERSION: 2.6.35-rc1
>         SUBJECT: duble spinlock  in function elp_start_xmit

Not only in elp_start_xmit. This driver is for a pretty old and slow isa
ethernet card and I think nobody cares. To quote a comment from the
source: "[...] the concurrency protection is particularly awful".

Thanks, 
   Christoph

Re: BUG: double spinlock in "drivers/net/3c505.c"

[David Miller]

From: Christoph Fritz <chf.fritz@googlemail.com>
Date: Tue, 08 Jun 2010 15:26:45 +0200

> On Mon, 2010-06-07 at 15:17 +0400, Alexander Strakh wrote: 
>> 	KERNEL_VERSION: 2.6.35-rc1
>>         SUBJECT: duble spinlock  in function elp_start_xmit
> 
> Not only in elp_start_xmit. This driver is for a pretty old and slow isa
> ethernet card and I think nobody cares. To quote a comment from the
> source: "[...] the concurrency protection is particularly awful".

Indeed, I spent some time trying to unravel the locking mess
for these call chains to check_3c505_dma() and it was just
too much to sanely cure.