lkml.org 
[lkml]   [2002]   [Aug]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch 2/21] reduced locking in buffer.c
Linus Torvalds wrote:
>
> On Sun, 11 Aug 2002, Andrew Morton wrote:
> >
> > Resend. Replace the buffer lru spinlock protection with
> > local_irq_disable and a cross-CPU call to invalidate them.
>
> This almost certainly breaks on sparc, where CPU cross-calls are
> non-maskable, so local_irq_disable doesn't do anything for them.
>
> Talk to Davem about this - there may be some workaround.

I have discussed it with David - he said it's OK in 2.5, but
not in 2.4, and he has eyeballed the diff.

However there's another thing to think about:

local_irq_disable();
atomic_inc();

If the architecture implements atomic_inc with spinlocks, this will
schedule with interrupts off with CONFIG_PREEMPT=y, I expect.

I can fix that with a preempt_disable() in there, but ick.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:22    [W:0.241 / U:0.152 seconds]
©2003-2011 Jasper Spaans. Advertise on this site