linux-kernel - Re: [PATCH v6 1/6] locking/qspinlock: relaxes cmpxchg & xchg ops in native code

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <55F6E4D1.3030005@hpe.com>
Date:	Mon, 14 Sep 2015 11:16:33 -0400
From:	Waiman Long <waiman.long@....com>
To:	Davidlohr Bueso <dave@...olabs.net>
CC:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Scott J Norton <scott.norton@...com>,
	Douglas Hatch <doug.hatch@...com>
Subject: Re: [PATCH v6 1/6] locking/qspinlock: relaxes cmpxchg & xchg ops
 in native code

On 09/11/2015 06:27 PM, Davidlohr Bueso wrote:
> On Fri, 11 Sep 2015, Waiman Long wrote:
>
>> @@ -46,7 +46,7 @@ static inline bool virt_queued_spin_lock(struct 
>> qspinlock *lock)
>>     if (!static_cpu_has(X86_FEATURE_HYPERVISOR))
>>         return false;
>>
>> -    while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0)
>> +    while (atomic_cmpxchg_acquire(&lock->val, 0, _Q_LOCKED_VAL) != 0)
>>         cpu_relax();
>
> This code has changed with Peter's recent ccas fix. And the whole 
> virt_queued_spin_lock()
> thing will now be under pv configs. So this doesn't apply to native 
> code anymore, so it
> looks like it should be dropped altogether.
>
> Thanks,
> Davidlohr

You are right. Patch 1 needs to be updated on top of PeterZ latest patch.

Cheers,
Longman
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/