From 7b642cd94bb96385cbdbb36a1952f129af6b1bbb Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 8 May 2024 06:21:35 +0200 Subject: Merging upstream version 4.19.304. Signed-off-by: Daniel Baumann --- drivers/base/driver.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) (limited to 'drivers/base/driver.c') diff --git a/drivers/base/driver.c b/drivers/base/driver.c index 857c8f1b8..668c6c8c2 100644 --- a/drivers/base/driver.c +++ b/drivers/base/driver.c @@ -29,6 +29,75 @@ static struct device *next_device(struct klist_iter *i) return dev; } +/** + * driver_set_override() - Helper to set or clear driver override. + * @dev: Device to change + * @override: Address of string to change (e.g. &device->driver_override); + * The contents will be freed and hold newly allocated override. + * @s: NUL-terminated string, new driver name to force a match, pass empty + * string to clear it ("" or "\n", where the latter is only for sysfs + * interface). + * @len: length of @s + * + * Helper to set or clear driver override in a device, intended for the cases + * when the driver_override field is allocated by driver/bus code. + * + * Returns: 0 on success or a negative error code on failure. + */ +int driver_set_override(struct device *dev, const char **override, + const char *s, size_t len) +{ + const char *new, *old; + char *cp; + + if (!override || !s) + return -EINVAL; + + /* + * The stored value will be used in sysfs show callback (sysfs_emit()), + * which has a length limit of PAGE_SIZE and adds a trailing newline. + * Thus we can store one character less to avoid truncation during sysfs + * show. + */ + if (len >= (PAGE_SIZE - 1)) + return -EINVAL; + + if (!len) { + /* Empty string passed - clear override */ + device_lock(dev); + old = *override; + *override = NULL; + device_unlock(dev); + kfree(old); + + return 0; + } + + cp = strnchr(s, len, '\n'); + if (cp) + len = cp - s; + + new = kstrndup(s, len, GFP_KERNEL); + if (!new) + return -ENOMEM; + + device_lock(dev); + old = *override; + if (cp != s) { + *override = new; + } else { + /* "\n" passed - clear override */ + kfree(new); + *override = NULL; + } + device_unlock(dev); + + kfree(old); + + return 0; +} +EXPORT_SYMBOL_GPL(driver_set_override); + /** * driver_for_each_device - Iterator for devices bound to a driver. * @drv: Driver we're iterating. -- cgit v1.2.3