From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [patch 4/5] xtime_lock: Convert to raw_seqlock
Date: Thu, 18 Feb 2010 11:49:28 +0100
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References: <20100217183740.486724334@linutronix.de>
	 <20100217184155.882793970@linutronix.de>
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To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>, Linux-Arch <linux-arch@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>, John Stultz <johnstul@us.ibm.com>

On Wed, 2010-02-17 at 18:47 +0000, Thomas Gleixner wrote:
> 
> xtime_lock needs a raw_spinlock in preempt-rt. Convert it to
> raw_seqlock and fix up all users.
> 
s/raw_spinlock/raw_seqlock/ ?

Maybe add an explanation on _why_ -rt needs this for the uninformed
amongst us.

-rt switches to sleeping spinlocks, but since the vdso is basically
userspace it cannot schedule, hence we need to keep using actual
spinlocks (this is also the reason the vdso things must not call into
lockdep)