From patchwork Fri Sep 18 09:55:01 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Russell King X-Patchwork-Id: 7214791 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 083609F380 for ; Fri, 18 Sep 2015 09:57:36 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 03A2420949 for ; Fri, 18 Sep 2015 09:57:35 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7A0432090E for ; Fri, 18 Sep 2015 09:57:33 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZcsOd-0005BX-0e; Fri, 18 Sep 2015 09:55:59 +0000 Received: from pandora.arm.linux.org.uk ([2001:4d48:ad52:3201:214:fdff:fe10:1be6]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZcsOY-0004mM-WA for linux-arm-kernel@lists.infradead.org; Fri, 18 Sep 2015 09:55:56 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=arm.linux.org.uk; s=pandora-2014; h=Date:Sender:Message-Id:Content-Type:Content-Transfer-Encoding:MIME-Version:Subject:Cc:To:From:References:In-Reply-To; bh=weiDwu1tOx5+CHb6KJG8+phEMU6clwKTZjgW/9FgTgY=; b=FdcPCsoxxqyzQJtl2YL3KW0j/3yV+4mjKQTkIYXdQUGK0iJxWQDtgiyZMh2nEAoV5AXgDQNflilG+JuEF5kGaMp1UwWb+UjxiUegOpLuAUtOgeF3R5xzxDyZ+cybIpR78qZAuReebb3NdX+CqlXXl1r3UXNdx0mzRj9pojD6MGc=; Received: from e0022681537dd.dyn.arm.linux.org.uk ([2002:4e20:1eda:1:222:68ff:fe15:37dd]:42412 helo=rmk-PC.arm.linux.org.uk) by pandora.arm.linux.org.uk with esmtpsa (TLSv1:AES128-SHA:128) (Exim 4.82_1-5b7a7c0-XX) (envelope-from ) id 1ZcsNk-0004tN-BL; Fri, 18 Sep 2015 10:55:04 +0100 Received: from rmk by rmk-PC.arm.linux.org.uk with local (Exim 4.82_1-5b7a7c0-XX) (envelope-from ) id 1ZcsNh-0001Bl-9h; Fri, 18 Sep 2015 10:55:01 +0100 In-Reply-To: <20150918094625.GB21084@n2100.arm.linux.org.uk> References: <20150918094625.GB21084@n2100.arm.linux.org.uk> From: Russell King To: Florian Fainelli Subject: [PATCH 2/7] phy: fix mdiobus module safety MIME-Version: 1.0 Content-Disposition: inline Message-Id: Date: Fri, 18 Sep 2015 10:55:01 +0100 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150918_025556_027495_AB73B53D X-CRM114-Status: GOOD ( 20.49 ) X-Spam-Score: -2.7 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Petazzoni , devicetree@vger.kernel.org, Sunil Goutham , Robert Richter , Frank Rowand , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Rob Herring , Michal Simek , netdev@vger.kernel.org, Soren Brinkmann , Iyappan Subramanian , Grant Likely , Li Yang , Keyur Chudgar , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED, T_DKIM_INVALID, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Re-implement the mdiobus module refcounting to ensure that we actually ensure that the mdiobus module code does not go away while we might call into it. The old scheme using bus->dev.driver was buggy, because bus->dev is a class device which never has a struct device_driver associated with it, and hence the associated code trying to obtain a refcount did nothing useful. Instead, take the approach that other subsystems do: pass the module when calling mdiobus_register(), and record that in the mii_bus struct. When we need to increment the module use count in the phy code, use this stored pointer. When the phy is deteched, drop the module refcount, remembering that the phy device might go away at that point. This doesn't stop the mii_bus going away while there are in-use phys - it merely stops the underlying code vanishing. Signed-off-by: Russell King --- drivers/net/phy/mdio_bus.c | 5 +++-- drivers/net/phy/phy_device.c | 32 ++++++++++++++++++-------------- include/linux/phy.h | 5 ++++- 3 files changed, 25 insertions(+), 17 deletions(-) diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c index 67553e13bd36..992406624b7c 100644 --- a/drivers/net/phy/mdio_bus.c +++ b/drivers/net/phy/mdio_bus.c @@ -244,7 +244,7 @@ static inline void of_mdiobus_link_phydev(struct mii_bus *mdio, * * Returns 0 on success or < 0 on error. */ -int mdiobus_register(struct mii_bus *bus) +int __mdiobus_register(struct mii_bus *bus, struct module *owner) { int i, err; @@ -255,6 +255,7 @@ int mdiobus_register(struct mii_bus *bus) BUG_ON(bus->state != MDIOBUS_ALLOCATED && bus->state != MDIOBUS_UNREGISTERED); + bus->owner = owner; bus->dev.parent = bus->parent; bus->dev.class = &mdio_bus_class; bus->dev.groups = NULL; @@ -296,7 +297,7 @@ int mdiobus_register(struct mii_bus *bus) device_del(&bus->dev); return err; } -EXPORT_SYMBOL(mdiobus_register); +EXPORT_SYMBOL(__mdiobus_register); void mdiobus_unregister(struct mii_bus *bus) { diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index c0f211127274..03adf328f49b 100644 --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -582,10 +582,15 @@ EXPORT_SYMBOL(phy_init_hw); int phy_attach_direct(struct net_device *dev, struct phy_device *phydev, u32 flags, phy_interface_t interface) { + struct mii_bus *bus = phydev->bus; struct device *d = &phydev->dev; - struct module *bus_module; int err; + if (!try_module_get(bus->owner)) { + dev_err(&dev->dev, "failed to get the bus module\n"); + return -EIO; + } + /* Assume that if there is no driver, that it doesn't * exist, and we should use the genphy driver. */ @@ -600,20 +605,13 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev, err = device_bind_driver(d); if (err) - return err; + goto error; } if (phydev->attached_dev) { dev_err(&dev->dev, "PHY already attached\n"); - return -EBUSY; - } - - /* Increment the bus module reference count */ - bus_module = phydev->bus->dev.driver ? - phydev->bus->dev.driver->owner : NULL; - if (!try_module_get(bus_module)) { - dev_err(&dev->dev, "failed to get the bus module\n"); - return -EIO; + err = -EBUSY; + goto error; } phydev->attached_dev = dev; @@ -636,6 +634,10 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev, phy_resume(phydev); return err; + +error: + module_put(bus->owner); + return err; } EXPORT_SYMBOL(phy_attach_direct); @@ -680,11 +682,9 @@ EXPORT_SYMBOL(phy_attach); */ void phy_detach(struct phy_device *phydev) { + struct mii_bus *bus; int i; - if (phydev->bus->dev.driver) - module_put(phydev->bus->dev.driver->owner); - phydev->attached_dev->phydev = NULL; phydev->attached_dev = NULL; phy_suspend(phydev); @@ -700,6 +700,10 @@ void phy_detach(struct phy_device *phydev) break; } } + + bus = phydev->bus; + + module_put(bus->owner); } EXPORT_SYMBOL(phy_detach); diff --git a/include/linux/phy.h b/include/linux/phy.h index 962387a192f1..11bce44f6d65 100644 --- a/include/linux/phy.h +++ b/include/linux/phy.h @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -153,6 +154,7 @@ struct sk_buff; * PHYs should register using this structure */ struct mii_bus { + struct module *owner; const char *name; char id[MII_BUS_ID_SIZE]; void *priv; @@ -198,7 +200,8 @@ static inline struct mii_bus *mdiobus_alloc(void) return mdiobus_alloc_size(0); } -int mdiobus_register(struct mii_bus *bus); +int __mdiobus_register(struct mii_bus *bus, struct module *owner); +#define mdiobus_register(bus) __mdiobus_register(bus, THIS_MODULE) void mdiobus_unregister(struct mii_bus *bus); void mdiobus_free(struct mii_bus *bus); struct mii_bus *devm_mdiobus_alloc_size(struct device *dev, int sizeof_priv);