From patchwork Wed Jul 12 04:23:01 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cyril Bur X-Patchwork-Id: 786983 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3x6m8771scz9s7v for ; Wed, 12 Jul 2017 14:25:11 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="sBj9WIAY"; dkim-atps=neutral DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id: References:In-Reply-To:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=qjEem17flUJ2OhqqUOPImBCZ65A43jFQKUwRepE9wEM=; b=sBj9WIAYnI7L+gfp3jXZ8RKq26 58nwy5wbueLP39SEi+MnLQgi5zgbZN6qG8sEkgShVHYGcWY5odjlcoOkfis/Jj3+jLzfh/1QA1HCw 1h8zAFqq7Zw83ATm/IvGRtBISpOPKajvj6MzcP7WZzvvBQFvoSniCAhd0pw9m7Da4hCY1qC/Q8gg3 9newtMnNB88UGNYPjSfK8aD1Du8SpYq5juwarMLRqoDQKtF5ow6NxxnVNDClIg+z/kFJ1lCHf2Nfz dyHjtmdTDsTeANvy6k7kAC0tVCuClNeSkgrEB0zR8dMGKXYZvBs4l69TvDJwYJRsT6Ftvo7cFddMZ Ihoth0tQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1dV9Cw-0002Oy-V6; Wed, 12 Jul 2017 04:25:02 +0000 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1dV9Cj-0001lm-Ro for linux-mtd@lists.infradead.org; Wed, 12 Jul 2017 04:25:00 +0000 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v6C4ORpD116790 for ; Wed, 12 Jul 2017 00:24:29 -0400 Received: from e23smtp04.au.ibm.com (e23smtp04.au.ibm.com [202.81.31.146]) by mx0a-001b2d01.pphosted.com with ESMTP id 2bncj8090s-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 12 Jul 2017 00:24:28 -0400 Received: from localhost by e23smtp04.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Wed, 12 Jul 2017 14:23:35 +1000 Received: from d23av06.au.ibm.com (d23av06.au.ibm.com [9.190.235.151]) by d23relay07.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v6C4NVvi19464326 for ; Wed, 12 Jul 2017 14:23:31 +1000 Received: from d23av06.au.ibm.com (localhost [127.0.0.1]) by d23av06.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v6C4NVbx007255 for ; Wed, 12 Jul 2017 14:23:31 +1000 Received: from ozlabs.au.ibm.com (ozlabs.au.ibm.com [9.192.253.14]) by d23av06.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id v6C4NVnx007247; Wed, 12 Jul 2017 14:23:31 +1000 Received: from camb691.ozlabs.ibm.com (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher DHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id CDFDFA0388; Wed, 12 Jul 2017 14:23:30 +1000 (AEST) From: Cyril Bur To: linuxppc-dev@lists.ozlabs.org, linux-mtd@lists.infradead.org Subject: [PATCH v3 07/10] powernv/opal-sensor: remove not needed lock Date: Wed, 12 Jul 2017 14:23:01 +1000 X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170712042304.19745-1-cyrilbur@gmail.com> References: <20170712042304.19745-1-cyrilbur@gmail.com> X-TM-AS-MML: disable x-cbid: 17071204-0012-0000-0000-00000255F3E0 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17071204-0013-0000-0000-0000076F6438 Message-Id: <20170712042304.19745-8-cyrilbur@gmail.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-07-11_13:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1706020000 definitions=main-1707120068 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170711_212450_924363_55B9DDB0 X-CRM114-Status: GOOD ( 15.77 ) X-Spam-Score: -1.1 (-) X-Spam-Report: SpamAssassin version 3.4.1 on bombadil.infradead.org summary: Content analysis details: (-1.1 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [148.163.156.1 listed in list.dnswl.org] -0.0 RCVD_IN_MSPIKE_H3 RBL: Good reputation (+3) [148.163.156.1 listed in wl.mailspike.net] 0.0 DKIM_ADSP_CUSTOM_MED No valid author signature, adsp_override is CUSTOM_MED 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (cyrilbur[at]gmail.com) 0.7 SPF_SOFTFAIL SPF: sender does not match SPF record (softfail) -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] -0.0 RCVD_IN_MSPIKE_WL Mailspike good senders 0.9 NML_ADSP_CUSTOM_MED ADSP custom_med hit, and not from a mailing list X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: stewart@linux.vnet.ibm.com, benh@kernel.crashing.org, alistair@popple.id.au, dwmw2@infradead.org, rlippert@google.com MIME-Version: 1.0 Sender: "linux-mtd" Errors-To: linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org From: Stewart Smith Parallel sensor reads could run out of async tokens due to opal_get_sensor_data grabbing tokens but then doing the sensor read behind a mutex, essentially serializing the (possibly asynchronous and relatively slow) sensor read. It turns out that the mutex isn't needed at all, not only should the OPAL interface allow concurrent reads, the implementation is certainly safe for that, and if any sensor we were reading from somewhere isn't, doing the mutual exclusion in the kernel is the wrong place to do it, OPAL should be doing it for the kernel. So, remove the mutex. Additionally, we shouldn't be printing out an error when we don't get a token as the only way this should happen is if we've been interrupted in down_interruptible() on the semaphore. Reported-by: Robert Lippert Signed-off-by: Stewart Smith Signed-off-by: Cyril Bur --- arch/powerpc/platforms/powernv/opal-sensor.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-) diff --git a/arch/powerpc/platforms/powernv/opal-sensor.c b/arch/powerpc/platforms/powernv/opal-sensor.c index aa267f120033..0a7074bb91dc 100644 --- a/arch/powerpc/platforms/powernv/opal-sensor.c +++ b/arch/powerpc/platforms/powernv/opal-sensor.c @@ -19,13 +19,10 @@ */ #include -#include #include #include #include -static DEFINE_MUTEX(opal_sensor_mutex); - /* * This will return sensor information to driver based on the requested sensor * handle. A handle is an opaque id for the powernv, read by the driver from the @@ -38,13 +35,9 @@ int opal_get_sensor_data(u32 sensor_hndl, u32 *sensor_data) __be32 data; token = opal_async_get_token_interruptible(); - if (token < 0) { - pr_err("%s: Couldn't get the token, returning\n", __func__); - ret = token; - goto out; - } + if (token < 0) + return token; - mutex_lock(&opal_sensor_mutex); ret = opal_sensor_read(sensor_hndl, token, &data); switch (ret) { case OPAL_ASYNC_COMPLETION: @@ -52,7 +45,7 @@ int opal_get_sensor_data(u32 sensor_hndl, u32 *sensor_data) if (ret) { pr_err("%s: Failed to wait for the async response, %d\n", __func__, ret); - goto out_token; + goto out; } ret = opal_error_code(opal_get_async_rc(msg)); @@ -73,10 +66,8 @@ int opal_get_sensor_data(u32 sensor_hndl, u32 *sensor_data) break; } -out_token: - mutex_unlock(&opal_sensor_mutex); - opal_async_release_token(token); out: + opal_async_release_token(token); return ret; } EXPORT_SYMBOL_GPL(opal_get_sensor_data);