From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Authentication-Results: lists.ozlabs.org; spf=permerror (mailfrom) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=benh@kernel.crashing.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 414dVg4P3KzF4Fc for ; Tue, 12 Jun 2018 15:19:55 +1000 (AEST) Received: from pasglop.ozlabs.ibm.com (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id w5C5JDa3008698; Tue, 12 Jun 2018 00:19:17 -0500 From: Benjamin Herrenschmidt To: openbmc@lists.ozlabs.org Cc: linux-kernel@vger.kernel.org, Joel Stanley , Andrew Jeffery , Greg Kroah-Hartman , Benjamin Herrenschmidt Subject: [RFC PATCH 1/5] fsi/scom: Add mutex around FSI2PIB accesses Date: Tue, 12 Jun 2018 15:19:07 +1000 Message-Id: <20180612051911.20690-2-benh@kernel.crashing.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180612051911.20690-1-benh@kernel.crashing.org> References: <20180612051911.20690-1-benh@kernel.crashing.org> X-BeenThere: openbmc@lists.ozlabs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: Development list for OpenBMC List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Jun 2018 05:19:56 -0000 Otherwise, multiple clients can open the driver and attempt to access the PIB at the same time, thus clobbering each other in the process. Signed-off-by: Benjamin Herrenschmidt --- drivers/fsi/fsi-scom.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/drivers/fsi/fsi-scom.c b/drivers/fsi/fsi-scom.c index c8eb5e5b94a7..3cba0eb645e1 100644 --- a/drivers/fsi/fsi-scom.c +++ b/drivers/fsi/fsi-scom.c @@ -37,6 +37,7 @@ struct scom_device { struct list_head link; struct fsi_device *fsi_dev; struct miscdevice mdev; + struct mutex lock; char name[32]; int idx; }; @@ -53,21 +54,26 @@ static int put_scom(struct scom_device *scom_dev, uint64_t value, int rc; uint32_t data; + mutex_lock(&scom_dev->lock); + data = cpu_to_be32((value >> 32) & 0xffffffff); rc = fsi_device_write(scom_dev->fsi_dev, SCOM_DATA0_REG, &data, sizeof(uint32_t)); if (rc) - return rc; + goto bail; data = cpu_to_be32(value & 0xffffffff); rc = fsi_device_write(scom_dev->fsi_dev, SCOM_DATA1_REG, &data, sizeof(uint32_t)); if (rc) - return rc; + goto bail; data = cpu_to_be32(SCOM_WRITE_CMD | addr); - return fsi_device_write(scom_dev->fsi_dev, SCOM_CMD_REG, &data, + rc = fsi_device_write(scom_dev->fsi_dev, SCOM_CMD_REG, &data, sizeof(uint32_t)); + bail: + mutex_unlock(&scom_dev->lock); + return rc; } static int get_scom(struct scom_device *scom_dev, uint64_t *value, @@ -76,27 +82,31 @@ static int get_scom(struct scom_device *scom_dev, uint64_t *value, uint32_t result, data; int rc; + + mutex_lock(&scom_dev->lock); *value = 0ULL; data = cpu_to_be32(addr); rc = fsi_device_write(scom_dev->fsi_dev, SCOM_CMD_REG, &data, sizeof(uint32_t)); if (rc) - return rc; + goto bail; rc = fsi_device_read(scom_dev->fsi_dev, SCOM_DATA0_REG, &result, sizeof(uint32_t)); if (rc) - return rc; + goto bail; *value |= (uint64_t)cpu_to_be32(result) << 32; rc = fsi_device_read(scom_dev->fsi_dev, SCOM_DATA1_REG, &result, sizeof(uint32_t)); if (rc) - return rc; + goto bail; *value |= cpu_to_be32(result); - return 0; + bail: + mutex_unlock(&scom_dev->lock); + return rc; } static ssize_t scom_read(struct file *filep, char __user *buf, size_t len, @@ -183,6 +193,7 @@ static int scom_probe(struct device *dev) if (!scom) return -ENOMEM; + mutex_init(&scom->lock); scom->idx = ida_simple_get(&scom_ida, 1, INT_MAX, GFP_KERNEL); snprintf(scom->name, sizeof(scom->name), "scom%d", scom->idx); scom->fsi_dev = fsi_dev; -- 2.17.0