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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, Borislav Petkov Subject: [PATCH 02/19] EDAC, altera: Kill off ACCESS_ONCE() Date: Mon, 23 Oct 2017 14:07:12 -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: 17102321-0052-0000-0000-00000275FAAB 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: 17102321-0053-0000-0000-00005269071F Message-Id: <1508792849-3115-2-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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mark Rutland 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 Altera EDAC 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 Acked-by: Thor Thayer Cc: Borislav Petkov --- drivers/edac/altera_edac.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) -- 2.5.2 diff --git a/drivers/edac/altera_edac.c b/drivers/edac/altera_edac.c index 346c4987b284..11d6419788c2 100644 --- a/drivers/edac/altera_edac.c +++ b/drivers/edac/altera_edac.c @@ -175,11 +175,11 @@ static ssize_t altr_sdr_mc_err_inject_write(struct file *file, /* * To trigger the error, we need to read the data back * (the data was written with errors above). - * The ACCESS_ONCE macros and printk are used to prevent the + * The READ_ONCE macros and printk are used to prevent the * the compiler optimizing these reads out. */ - reg = ACCESS_ONCE(ptemp[0]); - read_reg = ACCESS_ONCE(ptemp[1]); + reg = READ_ONCE(ptemp[0]); + read_reg = READ_ONCE(ptemp[1]); /* Force Read */ rmb(); @@ -618,7 +618,7 @@ static ssize_t altr_edac_device_trig(struct file *file, for (i = 0; i < (priv->trig_alloc_sz / sizeof(*ptemp)); i++) { /* Read data so we're in the correct state */ rmb(); - if (ACCESS_ONCE(ptemp[i])) + if (READ_ONCE(ptemp[i])) result = -1; /* Toggle Error bit (it is latched), leave ECC enabled */ writel(error_mask, (drvdata->base + priv->set_err_ofst)); @@ -635,7 +635,7 @@ static ssize_t altr_edac_device_trig(struct file *file, /* Read out written data. ECC error caused here */ for (i = 0; i < ALTR_TRIGGER_READ_WRD_CNT; i++) - if (ACCESS_ONCE(ptemp[i]) != i) + if (READ_ONCE(ptemp[i]) != i) edac_printk(KERN_ERR, EDAC_DEVICE, "Read doesn't match written data\n");