linux-kernel - Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock

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: <20150717101535.GR3644@twins.programming.kicks-ass.net>
Date:	Fri, 17 Jul 2015 12:15:35 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Will Deacon <will.deacon@....com>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	"paulmck@...ux.vnet.ibm.com" <paulmck@...ux.vnet.ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v2] memory-barriers: remove
 smp_mb__after_unlock_lock()

On Fri, Jul 17, 2015 at 10:32:21AM +0100, Will Deacon wrote:
> @@ -158,9 +140,7 @@ void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
>  
>  static inline void arch_spin_unlock(arch_spinlock_t *lock)
>  {
> -	SYNC_IO;
> -	__asm__ __volatile__("# arch_spin_unlock\n\t"
> -				PPC_RELEASE_BARRIER: : :"memory");
> +	smp_mb();
>  	lock->slock = 0;
>  }

Should we then also make smp_store_release() use sync instead of lwsync
to keep it consistent?
--
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/