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![Greg Kroah-Hartman](/assets/img/avatar_default.png)
Python likes to send an empty string for some sysfs files, including the driver_override field. When commit23d99baf9d
("PCI: Use driver_set_override() instead of open-coding") moved the PCI core to use the driver core function instead of hand-rolling their own handler, this showed up as a regression from some userspace tools, like DPDK. Fix this up by actually looking at the length of the string first instead of trusting that userspace got it correct. Fixes:23d99baf9d
("PCI: Use driver_set_override() instead of open-coding") Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: stable <stable@kernel.org> Reported-by: Stephen Hemminger <stephen@networkplumber.org> Tested-by: Huisong Li <lihuisong@huawei.com> Reviewed-by: Stephen Hemminger <stephen@networkplumber.org> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Link: https://lore.kernel.org/r/20220901163734.3583106-1-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
303 lines
7.6 KiB
C
303 lines
7.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* driver.c - centralized device driver management
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*
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* Copyright (c) 2002-3 Patrick Mochel
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* Copyright (c) 2002-3 Open Source Development Labs
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* Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
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* Copyright (c) 2007 Novell Inc.
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*/
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#include <linux/device/driver.h>
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#include <linux/device.h>
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/sysfs.h>
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#include "base.h"
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static struct device *next_device(struct klist_iter *i)
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{
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struct klist_node *n = klist_next(i);
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struct device *dev = NULL;
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struct device_private *dev_prv;
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if (n) {
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dev_prv = to_device_private_driver(n);
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dev = dev_prv->device;
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}
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return dev;
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}
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/**
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* driver_set_override() - Helper to set or clear driver override.
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* @dev: Device to change
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* @override: Address of string to change (e.g. &device->driver_override);
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* The contents will be freed and hold newly allocated override.
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* @s: NUL-terminated string, new driver name to force a match, pass empty
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* string to clear it ("" or "\n", where the latter is only for sysfs
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* interface).
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* @len: length of @s
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*
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* Helper to set or clear driver override in a device, intended for the cases
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* when the driver_override field is allocated by driver/bus code.
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*
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* Returns: 0 on success or a negative error code on failure.
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*/
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int driver_set_override(struct device *dev, const char **override,
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const char *s, size_t len)
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{
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const char *new, *old;
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char *cp;
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if (!override || !s)
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return -EINVAL;
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/*
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* The stored value will be used in sysfs show callback (sysfs_emit()),
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* which has a length limit of PAGE_SIZE and adds a trailing newline.
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* Thus we can store one character less to avoid truncation during sysfs
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* show.
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*/
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if (len >= (PAGE_SIZE - 1))
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return -EINVAL;
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/*
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* Compute the real length of the string in case userspace sends us a
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* bunch of \0 characters like python likes to do.
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*/
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len = strlen(s);
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if (!len) {
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/* Empty string passed - clear override */
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device_lock(dev);
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old = *override;
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*override = NULL;
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device_unlock(dev);
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kfree(old);
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return 0;
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}
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cp = strnchr(s, len, '\n');
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if (cp)
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len = cp - s;
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new = kstrndup(s, len, GFP_KERNEL);
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if (!new)
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return -ENOMEM;
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device_lock(dev);
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old = *override;
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if (cp != s) {
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*override = new;
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} else {
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/* "\n" passed - clear override */
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kfree(new);
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*override = NULL;
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}
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device_unlock(dev);
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kfree(old);
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return 0;
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}
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EXPORT_SYMBOL_GPL(driver_set_override);
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/**
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* driver_for_each_device - Iterator for devices bound to a driver.
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* @drv: Driver we're iterating.
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* @start: Device to begin with
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* @data: Data to pass to the callback.
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* @fn: Function to call for each device.
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*
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* Iterate over the @drv's list of devices calling @fn for each one.
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*/
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int driver_for_each_device(struct device_driver *drv, struct device *start,
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void *data, int (*fn)(struct device *, void *))
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{
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struct klist_iter i;
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struct device *dev;
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int error = 0;
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if (!drv)
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return -EINVAL;
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klist_iter_init_node(&drv->p->klist_devices, &i,
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start ? &start->p->knode_driver : NULL);
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while (!error && (dev = next_device(&i)))
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error = fn(dev, data);
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klist_iter_exit(&i);
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return error;
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}
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EXPORT_SYMBOL_GPL(driver_for_each_device);
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/**
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* driver_find_device - device iterator for locating a particular device.
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* @drv: The device's driver
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* @start: Device to begin with
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* @data: Data to pass to match function
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* @match: Callback function to check device
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*
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* This is similar to the driver_for_each_device() function above, but
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* it returns a reference to a device that is 'found' for later use, as
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* determined by the @match callback.
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*
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* The callback should return 0 if the device doesn't match and non-zero
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* if it does. If the callback returns non-zero, this function will
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* return to the caller and not iterate over any more devices.
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*/
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struct device *driver_find_device(struct device_driver *drv,
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struct device *start, const void *data,
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int (*match)(struct device *dev, const void *data))
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{
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struct klist_iter i;
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struct device *dev;
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if (!drv || !drv->p)
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return NULL;
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klist_iter_init_node(&drv->p->klist_devices, &i,
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(start ? &start->p->knode_driver : NULL));
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while ((dev = next_device(&i)))
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if (match(dev, data) && get_device(dev))
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break;
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klist_iter_exit(&i);
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return dev;
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}
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EXPORT_SYMBOL_GPL(driver_find_device);
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/**
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* driver_create_file - create sysfs file for driver.
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* @drv: driver.
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* @attr: driver attribute descriptor.
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*/
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int driver_create_file(struct device_driver *drv,
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const struct driver_attribute *attr)
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{
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int error;
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if (drv)
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error = sysfs_create_file(&drv->p->kobj, &attr->attr);
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else
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error = -EINVAL;
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return error;
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}
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EXPORT_SYMBOL_GPL(driver_create_file);
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/**
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* driver_remove_file - remove sysfs file for driver.
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* @drv: driver.
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* @attr: driver attribute descriptor.
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*/
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void driver_remove_file(struct device_driver *drv,
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const struct driver_attribute *attr)
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{
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if (drv)
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sysfs_remove_file(&drv->p->kobj, &attr->attr);
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}
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EXPORT_SYMBOL_GPL(driver_remove_file);
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int driver_add_groups(struct device_driver *drv,
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const struct attribute_group **groups)
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{
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return sysfs_create_groups(&drv->p->kobj, groups);
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}
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void driver_remove_groups(struct device_driver *drv,
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const struct attribute_group **groups)
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{
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sysfs_remove_groups(&drv->p->kobj, groups);
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}
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/**
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* driver_register - register driver with bus
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* @drv: driver to register
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*
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* We pass off most of the work to the bus_add_driver() call,
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* since most of the things we have to do deal with the bus
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* structures.
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*/
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int driver_register(struct device_driver *drv)
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{
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int ret;
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struct device_driver *other;
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if (!drv->bus->p) {
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pr_err("Driver '%s' was unable to register with bus_type '%s' because the bus was not initialized.\n",
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drv->name, drv->bus->name);
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return -EINVAL;
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}
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if ((drv->bus->probe && drv->probe) ||
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(drv->bus->remove && drv->remove) ||
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(drv->bus->shutdown && drv->shutdown))
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pr_warn("Driver '%s' needs updating - please use "
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"bus_type methods\n", drv->name);
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other = driver_find(drv->name, drv->bus);
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if (other) {
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pr_err("Error: Driver '%s' is already registered, "
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"aborting...\n", drv->name);
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return -EBUSY;
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}
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ret = bus_add_driver(drv);
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if (ret)
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return ret;
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ret = driver_add_groups(drv, drv->groups);
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if (ret) {
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bus_remove_driver(drv);
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return ret;
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}
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kobject_uevent(&drv->p->kobj, KOBJ_ADD);
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deferred_probe_extend_timeout();
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return ret;
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}
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EXPORT_SYMBOL_GPL(driver_register);
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/**
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* driver_unregister - remove driver from system.
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* @drv: driver.
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*
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* Again, we pass off most of the work to the bus-level call.
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*/
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void driver_unregister(struct device_driver *drv)
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{
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if (!drv || !drv->p) {
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WARN(1, "Unexpected driver unregister!\n");
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return;
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}
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driver_remove_groups(drv, drv->groups);
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bus_remove_driver(drv);
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}
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EXPORT_SYMBOL_GPL(driver_unregister);
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/**
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* driver_find - locate driver on a bus by its name.
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* @name: name of the driver.
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* @bus: bus to scan for the driver.
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*
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* Call kset_find_obj() to iterate over list of drivers on
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* a bus to find driver by name. Return driver if found.
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*
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* This routine provides no locking to prevent the driver it returns
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* from being unregistered or unloaded while the caller is using it.
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* The caller is responsible for preventing this.
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*/
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struct device_driver *driver_find(const char *name, struct bus_type *bus)
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{
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struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
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struct driver_private *priv;
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if (k) {
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/* Drop reference added by kset_find_obj() */
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kobject_put(k);
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priv = to_driver(k);
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return priv->driver;
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}
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return NULL;
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}
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EXPORT_SYMBOL_GPL(driver_find);
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