From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: [PATCH 32/34] xen/io: use __smp_XXX barriers Date: Wed, 30 Dec 2015 15:26:28 +0200 Message-ID: <1451473761-30019-33-git-send-email-mst@redhat.com> References: <1451473761-30019-1-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1451473761-30019-1-git-send-email-mst@redhat.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, Arnd Bergmann , Stefano Stabellini , Peter Zijlstra , Andrew Cooper , virtualization@lists.linux-foundation.org, David Vrabel , xen-devel@lists.xenproject.org, Boris Ostrovsky List-Id: linux-arch.vger.kernel.org include/xen/interface/io/ring.h uses full memory barriers to communicate with the other side. For guests compiled with CONFIG_SMP, smp_wmb and smp_mb would be sufficient, so mb() and wmb() here are only needed if a non-SMP guest runs on an SMP host. Switch to __smp_XXX barriers which serve this exact purpose. Signed-off-by: Michael S. Tsirkin --- include/xen/interface/io/ring.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h index 7dc685b..46dfc65 100644 --- a/include/xen/interface/io/ring.h +++ b/include/xen/interface/io/ring.h @@ -208,12 +208,12 @@ struct __name##_back_ring { \ #define RING_PUSH_REQUESTS(_r) do { \ - wmb(); /* back sees requests /before/ updated producer index */ \ + __smp_wmb(); /* back sees requests /before/ updated producer index */ \ (_r)->sring->req_prod = (_r)->req_prod_pvt; \ } while (0) #define RING_PUSH_RESPONSES(_r) do { \ - wmb(); /* front sees responses /before/ updated producer index */ \ + __smp_wmb(); /* front sees responses /before/ updated producer index */ \ (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ } while (0) @@ -250,9 +250,9 @@ struct __name##_back_ring { \ #define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ RING_IDX __old = (_r)->sring->req_prod; \ RING_IDX __new = (_r)->req_prod_pvt; \ - wmb(); /* back sees requests /before/ updated producer index */ \ + __smp_wmb(); /* back sees requests /before/ updated producer index */ \ (_r)->sring->req_prod = __new; \ - mb(); /* back sees new requests /before/ we check req_event */ \ + __smp_mb(); /* back sees new requests /before/ we check req_event */ \ (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ (RING_IDX)(__new - __old)); \ } while (0) @@ -260,9 +260,9 @@ struct __name##_back_ring { \ #define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ RING_IDX __old = (_r)->sring->rsp_prod; \ RING_IDX __new = (_r)->rsp_prod_pvt; \ - wmb(); /* front sees responses /before/ updated producer index */ \ + __smp_wmb(); /* front sees responses /before/ updated producer index */ \ (_r)->sring->rsp_prod = __new; \ - mb(); /* front sees new responses /before/ we check rsp_event */ \ + __smp_mb(); /* front sees new responses /before/ we check rsp_event */ \ (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ (RING_IDX)(__new - __old)); \ } while (0) @@ -271,7 +271,7 @@ struct __name##_back_ring { \ (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ if (_work_to_do) break; \ (_r)->sring->req_event = (_r)->req_cons + 1; \ - mb(); \ + __smp_mb(); \ (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ } while (0) @@ -279,7 +279,7 @@ struct __name##_back_ring { \ (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ if (_work_to_do) break; \ (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ - mb(); \ + __smp_mb(); \ (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ } while (0) -- MST From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:38008 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755464AbbL3Vw6 (ORCPT ); Wed, 30 Dec 2015 16:52:58 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id F296F14CAB2 for ; Wed, 30 Dec 2015 21:52:57 +0000 (UTC) Received: from redhat.com (vpn1-6-186.ams2.redhat.com [10.36.6.186]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id tBULquOp007610 for ; Wed, 30 Dec 2015 16:52:57 -0500 Date: Wed, 30 Dec 2015 15:26:28 +0200 From: "Michael S. Tsirkin" Subject: [PATCH 32/34] xen/io: use __smp_xxx barriers Message-ID: <1451473761-30019-33-git-send-email-mst@redhat.com> References: <1451473761-30019-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1451473761-30019-1-git-send-email-mst@redhat.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Arnd Bergmann , linux-arch@vger.kernel.org, Andrew Cooper , virtualization@lists.linux-foundation.org, Stefano Stabellini , Konrad Rzeszutek Wilk , Boris Ostrovsky , David Vrabel , xen-devel@lists.xenproject.org Message-ID: <20151230132628.WE-PybAeLWcvzctsD9YG9tXeeP3n-8-RG0cQOscnFxU@z> include/xen/interface/io/ring.h uses full memory barriers to communicate with the other side. For guests compiled with CONFIG_SMP, smp_wmb and smp_mb would be sufficient, so mb() and wmb() here are only needed if a non-SMP guest runs on an SMP host. Switch to __smp_XXX barriers which serve this exact purpose. Signed-off-by: Michael S. Tsirkin --- include/xen/interface/io/ring.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h index 7dc685b..46dfc65 100644 --- a/include/xen/interface/io/ring.h +++ b/include/xen/interface/io/ring.h @@ -208,12 +208,12 @@ struct __name##_back_ring { \ #define RING_PUSH_REQUESTS(_r) do { \ - wmb(); /* back sees requests /before/ updated producer index */ \ + __smp_wmb(); /* back sees requests /before/ updated producer index */ \ (_r)->sring->req_prod = (_r)->req_prod_pvt; \ } while (0) #define RING_PUSH_RESPONSES(_r) do { \ - wmb(); /* front sees responses /before/ updated producer index */ \ + __smp_wmb(); /* front sees responses /before/ updated producer index */ \ (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \ } while (0) @@ -250,9 +250,9 @@ struct __name##_back_ring { \ #define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \ RING_IDX __old = (_r)->sring->req_prod; \ RING_IDX __new = (_r)->req_prod_pvt; \ - wmb(); /* back sees requests /before/ updated producer index */ \ + __smp_wmb(); /* back sees requests /before/ updated producer index */ \ (_r)->sring->req_prod = __new; \ - mb(); /* back sees new requests /before/ we check req_event */ \ + __smp_mb(); /* back sees new requests /before/ we check req_event */ \ (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \ (RING_IDX)(__new - __old)); \ } while (0) @@ -260,9 +260,9 @@ struct __name##_back_ring { \ #define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \ RING_IDX __old = (_r)->sring->rsp_prod; \ RING_IDX __new = (_r)->rsp_prod_pvt; \ - wmb(); /* front sees responses /before/ updated producer index */ \ + __smp_wmb(); /* front sees responses /before/ updated producer index */ \ (_r)->sring->rsp_prod = __new; \ - mb(); /* front sees new responses /before/ we check rsp_event */ \ + __smp_mb(); /* front sees new responses /before/ we check rsp_event */ \ (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \ (RING_IDX)(__new - __old)); \ } while (0) @@ -271,7 +271,7 @@ struct __name##_back_ring { \ (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ if (_work_to_do) break; \ (_r)->sring->req_event = (_r)->req_cons + 1; \ - mb(); \ + __smp_mb(); \ (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \ } while (0) @@ -279,7 +279,7 @@ struct __name##_back_ring { \ (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ if (_work_to_do) break; \ (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \ - mb(); \ + __smp_mb(); \ (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \ } while (0) -- MST