From: Peter Zijlstra <peterz@infradead.org>
To: "Ma, Xindong" <xindong.ma@intel.com>
Cc: "stable@vger.kernel.org" <stable@vger.kernel.org>,
"stable-commits@vger.kernel.org" <stable-commits@vger.kernel.org>,
"Wysocki, Rafael J" <rafael.j.wysocki@intel.com>,
"ccross@google.com" <ccross@google.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"dvhart@linux.intel.com" <dvhart@linux.intel.com>,
"mingo@kernel.org" <mingo@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"Tu, Xiaobing" <xiaobing.tu@intel.com>
Subject: Re: Add memory barrier when waiting on futex
Date: Tue, 26 Nov 2013 09:26:26 +0100 [thread overview]
Message-ID: <20131126082626.GB789@laptop.programming.kicks-ass.net> (raw)
In-Reply-To: <3917C05D9F83184EAA45CE249FF1B1DD0252FBF3@SHSMSX103.ccr.corp.intel.com>
On Tue, Nov 26, 2013 at 01:07:25AM +0000, Ma, Xindong wrote:
> I've already aware that they've protected by spinlock, this is why I adding a memory barrier to fix it.
That doesn't make sense.. the spinlocks should provide the required
serialization, there's nothing to fix.
> I reproduced this issue several times on android which running on IA dual core.
I think you need to be more specific, in particular, if spinlocks do not
provide serialization on your IA32 device, I'd call that thing broken.
Adding random memory barriers is _WRONG_.
next prev parent reply other threads:[~2013-11-26 8:26 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-25 13:15 Add memory barrier when waiting on futex Ma, Xindong
2013-11-25 14:32 ` gregkh
2013-11-25 14:39 ` Peter Zijlstra
2013-11-25 19:18 ` Darren Hart
2013-11-26 1:07 ` Ma, Xindong
2013-11-26 8:26 ` Peter Zijlstra [this message]
2013-11-27 0:28 ` Ma, Xindong
2013-11-26 8:50 ` Peter Zijlstra
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