From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932162AbdJWVIH (ORCPT ); Mon, 23 Oct 2017 17:08:07 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:60828 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751552AbdJWVHl (ORCPT ); Mon, 23 Oct 2017 17:07:41 -0400 From: "Paul E. McKenney" To: mingo@kernel.org Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, will.deacon@arm.com, mark.rutland@arm.com, snitzer@redhat.com, thor.thayer@linux.intel.com, viro@zeniv.linux.org.uk, davem@davemloft.net, shuah@kernel.org, mpe@ellerman.id.au, tj@kernel.org, torvalds@linux-foundation.org, Jonathan Hunter , Thierry Reding Subject: [PATCH 03/19] firmware/ivc: Kill off ACCESS_ONCE() Date: Mon, 23 Oct 2017 14:07:13 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20171023210408.GA2930@linux.vnet.ibm.com> References: <20171023210408.GA2930@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17102321-0024-0000-0000-000002E6C96F X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007941; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000239; SDB=6.00935454; UDB=6.00471299; IPR=6.00715720; BA=6.00005656; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00017676; XFM=3.00000015; UTC=2017-10-23 21:07:38 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17102321-0025-0000-0000-000045D1D809 Message-Id: <1508792849-3115-3-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-10-23_11:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1710230296 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mark Rutland workqueue: kill off ACCESS_ONCE() For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't currently harmful. However, for some features it is necessary to instrument reads and writes separately, which is not possible with ACCESS_ONCE(). This distinction is critical to correct operation. It's possible to transform the bulk of kernel code using the Coccinelle script below. However, this doesn't handle comments, leaving references to ACCESS_ONCE() instances which have been removed. As a preparatory step, this patch converts the Tegra IVC code and comments to use {READ,WRITE}_ONCE() consistently. ---- virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland Cc: Jonathan Hunter Cc: Thierry Reding --- drivers/firmware/tegra/ivc.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/drivers/firmware/tegra/ivc.c b/drivers/firmware/tegra/ivc.c index a01461d63f68..00de793e6423 100644 --- a/drivers/firmware/tegra/ivc.c +++ b/drivers/firmware/tegra/ivc.c @@ -99,11 +99,11 @@ static inline bool tegra_ivc_empty(struct tegra_ivc *ivc, { /* * This function performs multiple checks on the same values with - * security implications, so create snapshots with ACCESS_ONCE() to + * security implications, so create snapshots with READ_ONCE() to * ensure that these checks use the same values. */ - u32 tx = ACCESS_ONCE(header->tx.count); - u32 rx = ACCESS_ONCE(header->rx.count); + u32 tx = READ_ONCE(header->tx.count); + u32 rx = READ_ONCE(header->rx.count); /* * Perform an over-full check to prevent denial of service attacks @@ -124,8 +124,8 @@ static inline bool tegra_ivc_empty(struct tegra_ivc *ivc, static inline bool tegra_ivc_full(struct tegra_ivc *ivc, struct tegra_ivc_header *header) { - u32 tx = ACCESS_ONCE(header->tx.count); - u32 rx = ACCESS_ONCE(header->rx.count); + u32 tx = READ_ONCE(header->tx.count); + u32 rx = READ_ONCE(header->rx.count); /* * Invalid cases where the counters indicate that the queue is over @@ -137,8 +137,8 @@ static inline bool tegra_ivc_full(struct tegra_ivc *ivc, static inline u32 tegra_ivc_available(struct tegra_ivc *ivc, struct tegra_ivc_header *header) { - u32 tx = ACCESS_ONCE(header->tx.count); - u32 rx = ACCESS_ONCE(header->rx.count); + u32 tx = READ_ONCE(header->tx.count); + u32 rx = READ_ONCE(header->rx.count); /* * This function isn't expected to be used in scenarios where an @@ -151,8 +151,8 @@ static inline u32 tegra_ivc_available(struct tegra_ivc *ivc, static inline void tegra_ivc_advance_tx(struct tegra_ivc *ivc) { - ACCESS_ONCE(ivc->tx.channel->tx.count) = - ACCESS_ONCE(ivc->tx.channel->tx.count) + 1; + WRITE_ONCE(ivc->tx.channel->tx.count, + READ_ONCE(ivc->tx.channel->tx.count) + 1); if (ivc->tx.position == ivc->num_frames - 1) ivc->tx.position = 0; @@ -162,8 +162,8 @@ static inline void tegra_ivc_advance_tx(struct tegra_ivc *ivc) static inline void tegra_ivc_advance_rx(struct tegra_ivc *ivc) { - ACCESS_ONCE(ivc->rx.channel->rx.count) = - ACCESS_ONCE(ivc->rx.channel->rx.count) + 1; + WRITE_ONCE(ivc->rx.channel->rx.count, + READ_ONCE(ivc->rx.channel->rx.count) + 1); if (ivc->rx.position == ivc->num_frames - 1) ivc->rx.position = 0; @@ -428,7 +428,7 @@ int tegra_ivc_notified(struct tegra_ivc *ivc) /* Copy the receiver's state out of shared memory. */ tegra_ivc_invalidate(ivc, ivc->rx.phys + offset); - state = ACCESS_ONCE(ivc->rx.channel->tx.state); + state = READ_ONCE(ivc->rx.channel->tx.state); if (state == TEGRA_IVC_STATE_SYNC) { offset = offsetof(struct tegra_ivc_header, tx.count); -- 2.5.2