Date: Thu, 28 Apr 2005 00:48:04 -0600 (MDT)
From: Zwane Mwaikambo <zwane@arm.linux.org.uk>
To: Ashok Raj <ashok.raj@intel.com>
cc: linux-kernel@vger.kernel.org, akpm@osdl.org, mingo@elte.hu,
       tony.luck@intel.com, gregkh@suse.de, hch@infradead.org
Subject: Re: Deferred handling of writes to /proc/irq/xx/smp_affinity
In-Reply-To: <20050427221538.A30702@unix-os.sc.intel.com>
Message-ID: <Pine.LNX.4.61.0504280039490.12903@montezuma.fsmlabs.com>
References: <20050427221538.A30702@unix-os.sc.intel.com>
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On Wed, 27 Apr 2005, Ashok Raj wrote:

> Hi Andrew and all
> 
> It is safe to re-program rte entries in ioapic only when an intr is pending. 
> Existing code does this incorrectly by reprogamming rte entries immediatly
> when a value is written to /proc/irq/xx/smp_affinity. IRQ_BALANCE code in 
> kernel does this right, but /proc/irq needs to be handled the same way so that 
> user mode irq_balancer wont lock up systems or loose interrupts in the race.
> 
> This is already fixed in ia64, introduced for i386 and x86_64.
> 
> since this touches 3 arch's managing in -mm for trial would be best to make
> sure nothing is broken, before considering for main line.

Ashok, thanks for doing this, i only have minor nitpicks, can we avoid 
the wrapper for irq_desc and just index it directly? And could we use 
static inline functions for MOVE_IRQ and SET_IRQ_INFO macros and use nop 
functions where required.

Thanks,
	Zwane

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