From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754597Ab2ALRI4 (ORCPT ); Thu, 12 Jan 2012 12:08:56 -0500 Received: from rcsinet15.oracle.com ([148.87.113.117]:21187 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754342Ab2ALRIu (ORCPT ); Thu, 12 Jan 2012 12:08:50 -0500 From: Konrad Rzeszutek Wilk To: jbarnes@virtuousgeek.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Cc: xen-devel@lists.xensource.com, Konrad Rzeszutek Wilk Subject: [PATCH 1/2] pci: Introduce __pci_reset_function_locked to be used when holding device_lock. Date: Thu, 12 Jan 2012 12:06:46 -0500 Message-Id: <1326388007-19178-2-git-send-email-konrad.wilk@oracle.com> X-Mailer: git-send-email 1.7.7.4 In-Reply-To: <1326388007-19178-1-git-send-email-konrad.wilk@oracle.com> References: <1326388007-19178-1-git-send-email-konrad.wilk@oracle.com> X-Source-IP: ucsinet22.oracle.com [156.151.31.94] X-CT-RefId: str=0001.0A090203.4F0F139D.0066,ss=1,re=0.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The use case of this is when a driver wants to call FLR when a device is attached to it using the SysFS "bind" or "unbind" functionality. The call chain when a user does "bind" looks as so: echo "0000:01.07.0" > /sys/bus/pci/drivers/XXXX/bind and ends up calling: driver_bind: device_lock(dev); <=== TAKES LOCK XXXX_probe: .. pci_enable_device() ...__pci_reset_function(), which calls pci_dev_reset(dev, 0): if (!0) { device_lock(dev) <==== DEADLOCK The __pci_reset_function_locked function allows the the drivers 'probe' function to call the "pci_reset_function" while still holding the driver mutex lock. Signed-off-by: Konrad Rzeszutek Wilk --- drivers/pci/pci.c | 25 +++++++++++++++++++++++++ include/linux/pci.h | 1 + 2 files changed, 26 insertions(+), 0 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 97fff78..192be5d 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3163,6 +3163,31 @@ int __pci_reset_function(struct pci_dev *dev) EXPORT_SYMBOL_GPL(__pci_reset_function); /** + * __pci_reset_function_locked - reset a PCI device function while holding + * the @dev mutex lock. + * @dev: PCI device to reset + * + * Some devices allow an individual function to be reset without affecting + * other functions in the same device. The PCI device must be responsive + * to PCI config space in order to use this function. + * + * The device function is presumed to be unused and the caller is holding + * the device mutex lock when this function is called. + * Resetting the device will make the contents of PCI configuration space + * random, so any caller of this must be prepared to reinitialise the + * device including MSI, bus mastering, BARs, decoding IO and memory spaces, + * etc. + * + * Returns 0 if the device function was successfully reset or negative if the + * device doesn't support resetting a single function. + */ +int __pci_reset_function_locked(struct pci_dev *dev) +{ + return pci_dev_reset(dev, 1); +} +EXPORT_SYMBOL_GPL(__pci_reset_function_locked); + +/** * pci_probe_reset_function - check whether the device can be safely reset * @dev: PCI device to reset * diff --git a/include/linux/pci.h b/include/linux/pci.h index a16b1df..65c2d8a 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -817,6 +817,7 @@ int pcie_set_readrq(struct pci_dev *dev, int rq); int pcie_get_mps(struct pci_dev *dev); int pcie_set_mps(struct pci_dev *dev, int mps); int __pci_reset_function(struct pci_dev *dev); +int __pci_reset_function_locked(struct pci_dev *dev); int pci_reset_function(struct pci_dev *dev); void pci_update_resource(struct pci_dev *dev, int resno); int __must_check pci_assign_resource(struct pci_dev *dev, int i); -- 1.7.7.4