Messages in this thread | | | Date | Fri, 4 Aug 2006 14:21:55 +0200 | From | Willy Tarreau <> | Subject | Re: [PATCH 2.4.32] Fix AVM C4 ISDN card init problems with newer CPUs |
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On Fri, Aug 04, 2006 at 12:39:12PM +0200, Michael Buesch wrote: > On Friday 04 August 2006 08:56, Willy Tarreau wrote: > > On Thu, Aug 03, 2006 at 06:56:15PM +0100, Alan Cox wrote: > > > Ar Iau, 2006-08-03 am 19:53 +0300, ysgrifennodd Jukka Partanen: > > > > AVM C4 ISDN NIC: Add three memory barriers, taken from 2.6.7, > > > > (they are there in 2.6.17.7 too), to fix module initialization > > > > problems appearing with at least some newer Celerons and > > > > Pentium III. > > > > > > Should be using cpu_relax() I think. Its a polled busy loop so you want > > > other CPU threads to run if possible. > > > > You mean like this ? Here's the patch for 2.6, I'll queue the same for 2.4 > > if it's alright. > > > > > Alan > > > > Regards, > > Willy > > > > From 512d12bd7ce9c0a15dfd91a6f7c2970c92b3abdd Mon Sep 17 00:00:00 2001 > > From: Willy Tarreau <w@1wt.eu> > > Date: Fri, 4 Aug 2006 08:50:10 +0200 > > Subject: [PATCH] AVM C4 ISDN card : use cpu_relax() in busy loops > > > > As suggested by Alan, use cpu_relax() in 3 busy loops : "It's a > > polled busy loop so you want other CPU threads to run if possible". > > > > Signed-off-by: Willy Tarreau <w@1wt.eu> > > --- > > drivers/isdn/hardware/avm/c4.c | 4 ++++ > > 1 files changed, 4 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/isdn/hardware/avm/c4.c b/drivers/isdn/hardware/avm/c4.c > > index f7253b2..aee278e 100644 > > --- a/drivers/isdn/hardware/avm/c4.c > > +++ b/drivers/isdn/hardware/avm/c4.c > > @@ -22,6 +22,7 @@ #include <linux/capi.h> > > #include <linux/kernelcapi.h> > > #include <linux/init.h> > > #include <asm/io.h> > > +#include <asm/processor.h> > > #include <asm/uaccess.h> > > #include <linux/netdevice.h> > > #include <linux/isdn/capicmd.h> > > @@ -150,6 +151,7 @@ static inline int wait_for_doorbell(avmc > > if (!time_before(jiffies, stop)) > > return -1; > > mb(); > > + cpu_relax(); > > cpu_relax() implies a memory barrier.
OK fine. Reading from various asm-xxx/processor.h files, I was not sure about this. I will repost it fixed and queue it for next 2.4 too.
> Greetings Michael.
Thanks, Willy
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