Re: 3c59x vortex_timer rt hack (was: rt20 patch question)

[Steven Rostedt]

On Fri, 12 May 2006, Andrew Morton wrote:

> Steven Rostedt <rostedt@xxxxxxxxxxx> 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)
-
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