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From: Will Deacon <will.deacon@arm.com>
To: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
	arnd@arndb.de, waiman.long@hp.com, peterz@infradead.org
Subject: Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian
Date: Wed, 8 Jun 2016 10:22:44 +0100	[thread overview]
Message-ID: <20160608092244.GA27029@arm.com> (raw)
In-Reply-To: <1464862148-5672-1-git-send-email-xinhui.pan@linux.vnet.ibm.com>

On Thu, Jun 02, 2016 at 06:09:08PM +0800, Pan Xinhui wrote:
> strcut __qrwlock has different layout in big endian machine. we need set
> the __qrwlock->wmode to NULL, and the address is not &lock->cnts in big
> endian machine.
> 
> Do as what read unlock does. we are lucky that the __qrwlock->wmode's
> val is _QW_LOCKED.

Doesn't this have wider implications for the qrwlocks, for example:

  while ((cnts & _QW_WMASK) == _QW_LOCKED) { ... }

would actually end up looking at the wrong field of the lock?

Shouldn't we just remove the #ifdef __LITTLE_ENDIAN stuff from __qrwlock,
given that all the struct members are u8?

Will

  parent reply	other threads:[~2016-06-08  9:22 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-02 10:09 [PATCH] locking/qrwlock: fix write unlock issue in big endian Pan Xinhui
2016-06-02 10:44 ` Arnd Bergmann
2016-06-02 11:01   ` xinhui
2016-06-02 11:15     ` Peter Zijlstra
2016-06-03  7:20       ` xinhui
2016-06-02 11:02   ` Peter Zijlstra
2016-06-03  7:17     ` xinhui
2016-06-03  7:17     ` xinhui
     [not found]     ` <201606030718.u537FQg0009963@mx0a-001b2d01.pphosted.com>
2016-06-03 20:57       ` Waiman Long
2016-06-03 20:57         ` Waiman Long
2016-06-06  3:15         ` xinhui
2016-06-06  3:15         ` xinhui
2016-06-08  9:22 ` Will Deacon [this message]
2016-06-14  6:11   ` xinhui
2016-06-14 10:40     ` Will Deacon
2016-06-15  3:47       ` xinhui

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