Re: 3c59x vortex_timer rt hack

[Mark Hounschell <markh@compro.net>]

Steven Rostedt wrote:
> On Fri, 12 May 2006, Andrew Morton wrote:
> 
>> Steven Rostedt <rostedt@goodmis.org> wrote:
>>>  Use this patch instead.  It needs an irq disable.  But, believe it or not,
>>>  on SMP this is actually better.  If the irq is shared (as it is in Mark's
>>>  case), we don't stop the irq of other devices from being handled on
>>>  another CPU (unfortunately for Mark, he pinned all interrupts to one CPU).
>>>
>>>  Andrew,
>>>
>>>  should this be changed in mainline too?
>> I suppose so - we're taking the lock with spin_lock_bh(), but it can also
>> be taken by this CPU from the interrupt, so it'll deadlock.  But lo!  We've
>> done disable_irq(), so the interrupt won't be happening.
>>
>> So yes, doing spin_lock_irq() (irqrestore isn't needed in a timer handler)
>> instead of disable_irq() in vortex_timer() looks OK.
> 
> Ah, you're right, it's an over kill.
> 
> Ingo, here's the patch without irqsave
> 
> -- Steve
> 
> Index: linux-2.6.16-rt20/drivers/net/3c59x.c
> ===================================================================
> --- linux-2.6.16-rt20.orig/drivers/net/3c59x.c	2006-05-12 10:27:36.000000000 -0400
> +++ linux-2.6.16-rt20/drivers/net/3c59x.c	2006-05-12 11:03:39.000000000 -0400
> @@ -1897,7 +1897,7 @@ vortex_timer(unsigned long data)
> 
>  	if (vp->medialock)
>  		goto leave_media_alone;
> -	disable_irq(dev->irq);
> +	spin_lock_irq(&vp->lock);
>  	old_window = ioread16(ioaddr + EL3_CMD) >> 13;
>  	EL3WINDOW(4);
>  	media_status = ioread16(ioaddr + Wn4_Media);
> @@ -1919,7 +1919,6 @@ vortex_timer(unsigned long data)
>  		break;
>  	case XCVR_MII: case XCVR_NWAY:
>  		{
> -			spin_lock_bh(&vp->lock);
>  			mii_status = mdio_read(dev, vp->phys[0], MII_BMSR);
>  			if (!(mii_status & BMSR_LSTATUS)) {
>  				/* Re-read to get actual link status */
> @@ -1957,7 +1956,6 @@ vortex_timer(unsigned long data)
>  			} else {
>  				netif_carrier_off(dev);
>  			}
> -			spin_unlock_bh(&vp->lock);
>  		}
>  		break;
>  	  default:					/* Other media types handled by Tx timeouts. */
> @@ -2000,7 +1998,7 @@ vortex_timer(unsigned long data)
>  		/* AKPM: FIXME: Should reset Rx & Tx here.  P60 of 3c90xc.pdf */
>  	}
>  	EL3WINDOW(old_window);
> -	enable_irq(dev->irq);
> +	spin_unlock_irq(&vp->lock);
> 
>  leave_media_alone:
>  	if (vortex_debug > 2)
> 

I have tried this one and it seems OK. No BUGs or disconnections for
over an hour now and I'm beating it good.

Mark