linux-kernel - Re: [PATCH v10 07/19] qspinlock: Use a simple write to grab the lock, if applicable

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Date:	Thu, 8 May 2014 21:02:03 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Waiman Long <Waiman.Long@...com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, linux-arch@...r.kernel.org,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org,
	xen-devel@...ts.xenproject.org, kvm@...r.kernel.org,
	Paolo Bonzini <paolo.bonzini@...il.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Rik van Riel <riel@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>,
	David Vrabel <david.vrabel@...rix.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Gleb Natapov <gleb@...hat.com>,
	Scott J Norton <scott.norton@...com>,
	Chegu Vinod <chegu_vinod@...com>
Subject: Re: [PATCH v10 07/19] qspinlock: Use a simple write to grab the
 lock, if applicable

On Wed, May 07, 2014 at 11:01:35AM -0400, Waiman Long wrote:
>  /**
> + * get_qlock - Set the lock bit and own the lock
> + * @lock: Pointer to queue spinlock structure
> + *
> + * This routine should only be called when the caller is the only one
> + * entitled to acquire the lock.
> + */
> +static __always_inline void get_qlock(struct qspinlock *lock)

set_locked()

> +{
> +	struct __qspinlock *l = (void *)lock;
> +
> +	barrier();
> +	ACCESS_ONCE(l->locked) = _Q_LOCKED_VAL;
> +	barrier();
> +}

get_qlock() is just horrible. The function doesn't actually _get_
anything, and qlock is not in line with the rest of the naming.
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