Revision 9f141d6ef6258a3a37a045842d9ba7e68f368956 authored by Jan Kara on 19 October 2016, 12:34:31 UTC, committed by Dan Williams on 27 December 2016, 04:29:25 UTC
Currently ->iomap_begin() handler is called with entry lock held. If the filesystem held any locks between ->iomap_begin() and ->iomap_end() (such as ext4 which will want to hold transaction open), this would cause lock inversion with the iomap_apply() from standard IO path which first calls ->iomap_begin() and only then calls ->actor() callback which grabs entry locks for DAX (if it faults when copying from/to user provided buffers). Fix the problem by nesting grabbing of entry lock inside ->iomap_begin() - ->iomap_end() pair. Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
1 parent f449b93
fpga-bridge.c
/*
* FPGA Bridge Framework Driver
*
* Copyright (C) 2013-2016 Altera Corporation, All Rights Reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/fpga/fpga-bridge.h>
#include <linux/idr.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
static DEFINE_IDA(fpga_bridge_ida);
static struct class *fpga_bridge_class;
/* Lock for adding/removing bridges to linked lists*/
spinlock_t bridge_list_lock;
static int fpga_bridge_of_node_match(struct device *dev, const void *data)
{
return dev->of_node == data;
}
/**
* fpga_bridge_enable - Enable transactions on the bridge
*
* @bridge: FPGA bridge
*
* Return: 0 for success, error code otherwise.
*/
int fpga_bridge_enable(struct fpga_bridge *bridge)
{
dev_dbg(&bridge->dev, "enable\n");
if (bridge->br_ops && bridge->br_ops->enable_set)
return bridge->br_ops->enable_set(bridge, 1);
return 0;
}
EXPORT_SYMBOL_GPL(fpga_bridge_enable);
/**
* fpga_bridge_disable - Disable transactions on the bridge
*
* @bridge: FPGA bridge
*
* Return: 0 for success, error code otherwise.
*/
int fpga_bridge_disable(struct fpga_bridge *bridge)
{
dev_dbg(&bridge->dev, "disable\n");
if (bridge->br_ops && bridge->br_ops->enable_set)
return bridge->br_ops->enable_set(bridge, 0);
return 0;
}
EXPORT_SYMBOL_GPL(fpga_bridge_disable);
/**
* of_fpga_bridge_get - get an exclusive reference to a fpga bridge
*
* @np: node pointer of a FPGA bridge
* @info: fpga image specific information
*
* Return fpga_bridge struct if successful.
* Return -EBUSY if someone already has a reference to the bridge.
* Return -ENODEV if @np is not a FPGA Bridge.
*/
struct fpga_bridge *of_fpga_bridge_get(struct device_node *np,
struct fpga_image_info *info)
{
struct device *dev;
struct fpga_bridge *bridge;
int ret = -ENODEV;
dev = class_find_device(fpga_bridge_class, NULL, np,
fpga_bridge_of_node_match);
if (!dev)
goto err_dev;
bridge = to_fpga_bridge(dev);
if (!bridge)
goto err_dev;
bridge->info = info;
if (!mutex_trylock(&bridge->mutex)) {
ret = -EBUSY;
goto err_dev;
}
if (!try_module_get(dev->parent->driver->owner))
goto err_ll_mod;
dev_dbg(&bridge->dev, "get\n");
return bridge;
err_ll_mod:
mutex_unlock(&bridge->mutex);
err_dev:
put_device(dev);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(of_fpga_bridge_get);
/**
* fpga_bridge_put - release a reference to a bridge
*
* @bridge: FPGA bridge
*/
void fpga_bridge_put(struct fpga_bridge *bridge)
{
dev_dbg(&bridge->dev, "put\n");
bridge->info = NULL;
module_put(bridge->dev.parent->driver->owner);
mutex_unlock(&bridge->mutex);
put_device(&bridge->dev);
}
EXPORT_SYMBOL_GPL(fpga_bridge_put);
/**
* fpga_bridges_enable - enable bridges in a list
* @bridge_list: list of FPGA bridges
*
* Enable each bridge in the list. If list is empty, do nothing.
*
* Return 0 for success or empty bridge list; return error code otherwise.
*/
int fpga_bridges_enable(struct list_head *bridge_list)
{
struct fpga_bridge *bridge;
struct list_head *node;
int ret;
list_for_each(node, bridge_list) {
bridge = list_entry(node, struct fpga_bridge, node);
ret = fpga_bridge_enable(bridge);
if (ret)
return ret;
}
return 0;
}
EXPORT_SYMBOL_GPL(fpga_bridges_enable);
/**
* fpga_bridges_disable - disable bridges in a list
*
* @bridge_list: list of FPGA bridges
*
* Disable each bridge in the list. If list is empty, do nothing.
*
* Return 0 for success or empty bridge list; return error code otherwise.
*/
int fpga_bridges_disable(struct list_head *bridge_list)
{
struct fpga_bridge *bridge;
struct list_head *node;
int ret;
list_for_each(node, bridge_list) {
bridge = list_entry(node, struct fpga_bridge, node);
ret = fpga_bridge_disable(bridge);
if (ret)
return ret;
}
return 0;
}
EXPORT_SYMBOL_GPL(fpga_bridges_disable);
/**
* fpga_bridges_put - put bridges
*
* @bridge_list: list of FPGA bridges
*
* For each bridge in the list, put the bridge and remove it from the list.
* If list is empty, do nothing.
*/
void fpga_bridges_put(struct list_head *bridge_list)
{
struct fpga_bridge *bridge;
struct list_head *node, *next;
unsigned long flags;
list_for_each_safe(node, next, bridge_list) {
bridge = list_entry(node, struct fpga_bridge, node);
fpga_bridge_put(bridge);
spin_lock_irqsave(&bridge_list_lock, flags);
list_del(&bridge->node);
spin_unlock_irqrestore(&bridge_list_lock, flags);
}
}
EXPORT_SYMBOL_GPL(fpga_bridges_put);
/**
* fpga_bridges_get_to_list - get a bridge, add it to a list
*
* @np: node pointer of a FPGA bridge
* @info: fpga image specific information
* @bridge_list: list of FPGA bridges
*
* Get an exclusive reference to the bridge and and it to the list.
*
* Return 0 for success, error code from of_fpga_bridge_get() othewise.
*/
int fpga_bridge_get_to_list(struct device_node *np,
struct fpga_image_info *info,
struct list_head *bridge_list)
{
struct fpga_bridge *bridge;
unsigned long flags;
bridge = of_fpga_bridge_get(np, info);
if (IS_ERR(bridge))
return PTR_ERR(bridge);
spin_lock_irqsave(&bridge_list_lock, flags);
list_add(&bridge->node, bridge_list);
spin_unlock_irqrestore(&bridge_list_lock, flags);
return 0;
}
EXPORT_SYMBOL_GPL(fpga_bridge_get_to_list);
static ssize_t name_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct fpga_bridge *bridge = to_fpga_bridge(dev);
return sprintf(buf, "%s\n", bridge->name);
}
static ssize_t state_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct fpga_bridge *bridge = to_fpga_bridge(dev);
int enable = 1;
if (bridge->br_ops && bridge->br_ops->enable_show)
enable = bridge->br_ops->enable_show(bridge);
return sprintf(buf, "%s\n", enable ? "enabled" : "disabled");
}
static DEVICE_ATTR_RO(name);
static DEVICE_ATTR_RO(state);
static struct attribute *fpga_bridge_attrs[] = {
&dev_attr_name.attr,
&dev_attr_state.attr,
NULL,
};
ATTRIBUTE_GROUPS(fpga_bridge);
/**
* fpga_bridge_register - register a fpga bridge driver
* @dev: FPGA bridge device from pdev
* @name: FPGA bridge name
* @br_ops: pointer to structure of fpga bridge ops
* @priv: FPGA bridge private data
*
* Return: 0 for success, error code otherwise.
*/
int fpga_bridge_register(struct device *dev, const char *name,
const struct fpga_bridge_ops *br_ops, void *priv)
{
struct fpga_bridge *bridge;
int id, ret = 0;
if (!name || !strlen(name)) {
dev_err(dev, "Attempt to register with no name!\n");
return -EINVAL;
}
bridge = kzalloc(sizeof(*bridge), GFP_KERNEL);
if (!bridge)
return -ENOMEM;
id = ida_simple_get(&fpga_bridge_ida, 0, 0, GFP_KERNEL);
if (id < 0) {
ret = id;
goto error_kfree;
}
mutex_init(&bridge->mutex);
INIT_LIST_HEAD(&bridge->node);
bridge->name = name;
bridge->br_ops = br_ops;
bridge->priv = priv;
device_initialize(&bridge->dev);
bridge->dev.class = fpga_bridge_class;
bridge->dev.parent = dev;
bridge->dev.of_node = dev->of_node;
bridge->dev.id = id;
dev_set_drvdata(dev, bridge);
ret = dev_set_name(&bridge->dev, "br%d", id);
if (ret)
goto error_device;
ret = device_add(&bridge->dev);
if (ret)
goto error_device;
of_platform_populate(dev->of_node, NULL, NULL, dev);
dev_info(bridge->dev.parent, "fpga bridge [%s] registered\n",
bridge->name);
return 0;
error_device:
ida_simple_remove(&fpga_bridge_ida, id);
error_kfree:
kfree(bridge);
return ret;
}
EXPORT_SYMBOL_GPL(fpga_bridge_register);
/**
* fpga_bridge_unregister - unregister a fpga bridge driver
* @dev: FPGA bridge device from pdev
*/
void fpga_bridge_unregister(struct device *dev)
{
struct fpga_bridge *bridge = dev_get_drvdata(dev);
/*
* If the low level driver provides a method for putting bridge into
* a desired state upon unregister, do it.
*/
if (bridge->br_ops && bridge->br_ops->fpga_bridge_remove)
bridge->br_ops->fpga_bridge_remove(bridge);
device_unregister(&bridge->dev);
}
EXPORT_SYMBOL_GPL(fpga_bridge_unregister);
static void fpga_bridge_dev_release(struct device *dev)
{
struct fpga_bridge *bridge = to_fpga_bridge(dev);
ida_simple_remove(&fpga_bridge_ida, bridge->dev.id);
kfree(bridge);
}
static int __init fpga_bridge_dev_init(void)
{
spin_lock_init(&bridge_list_lock);
fpga_bridge_class = class_create(THIS_MODULE, "fpga_bridge");
if (IS_ERR(fpga_bridge_class))
return PTR_ERR(fpga_bridge_class);
fpga_bridge_class->dev_groups = fpga_bridge_groups;
fpga_bridge_class->dev_release = fpga_bridge_dev_release;
return 0;
}
static void __exit fpga_bridge_dev_exit(void)
{
class_destroy(fpga_bridge_class);
ida_destroy(&fpga_bridge_ida);
}
MODULE_DESCRIPTION("FPGA Bridge Driver");
MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
MODULE_LICENSE("GPL v2");
subsys_initcall(fpga_bridge_dev_init);
module_exit(fpga_bridge_dev_exit);
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