linux-kernel - Re: [PATCH 1/8] cpumask: Replace cpumask_of_cpu with cpumask_of_cpu

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Date:	Wed, 23 Jul 2008 13:20:42 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	Mike Travis <travis@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Jack Steiner <steiner@....com>, linux-kernel@...r.kernel.org,
	Len Brown <len.brown@...el.com>,
	Dave Jones <davej@...emonkey.org.uk>,
	Paul Jackson <pj@....com>,
	Tigran Aivazian <tigran@...azian.fsnet.co.uk>,
	Robert Richter <robert.richter@....com>,
	Greg Banks <gnb@....com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Adrian Bunk <bunk@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andreas Schwab <schwab@...e.de>,
	Johannes Weiner <hannes@...urebad.de>
Subject: Re: [PATCH 1/8] cpumask: Replace cpumask_of_cpu with
	cpumask_of_cpu_ptr


* Rusty Russell <rusty@...tcorp.com.au> wrote:

> > I wouldn't mind it at all, and since it's almost always calling a 
> > function that requires a cpumask_t pointer (like the cpu_* ops or 
> > set_cpus_allowed_ptr) then there shouldn't be too many "pointer 
> > dereference" penalties.  I'm just always a bit hesitant to make too 
> > many generic changes since I have only x86 and ia64 machines to test 
> > with.
> 
> The simple version is just a static array of [NR_CPUS] cpumask_t's.  
> Do that, with an override for smarter archs?
> 
> I really REALLY prefer that over the fairly tortuous macros.

a fresh commit in -git has exposed the topology.h mess - see the hack 
below. We now have diverging versions of topology_core_siblings() 
semantics - that sure cannot be right. Mike?

	Ingo

------->
commit 695a6b456307455a10059512208e8ed0d376ecd3
Author: Ingo Molnar <mingo@...e.hu>
Date:   Wed Jul 23 13:19:44 2008 +0200

    topology: work around topology_core_siblings() breakage
    
    work around:
    
    drivers/net/sfc/efx.c: In function ‘efx_probe_interrupts':
    drivers/net/sfc/efx.c:845: error: lvalue required as unary ‘&' operand
    
    the topology API is a mess right now ...
    
    Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 drivers/net/sfc/efx.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index 45c72ee..1ababfa 100644
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -842,8 +842,10 @@ static void efx_probe_interrupts(struct efx_nic *efx)
 			for_each_online_cpu(cpu) {
 				if (!cpu_isset(cpu, core_mask)) {
 					++efx->rss_queues;
+#if 0
 					cpus_or(core_mask, core_mask,
 						topology_core_siblings(cpu));
+#endif
 				}
 			}
 		} else {

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