[PATCH v2 4/4] cdx: use generic driver_override infrastructure
From: Runyu Xiao <hidden>
Date: 2026-06-04 03:58:14
Also in:
driver-core, linux-arm-msm, linux-remoteproc, lkml, stable
Subsystem:
amd cdx bus driver, the rest · Maintainers:
Nipun Gupta, Nikhil Agarwal, Linus Torvalds
CDX devices still keep driver_override in bus-private storage. The sysfs write side updates that string through driver_set_override(), which replaces the pointer and frees the old value. However, driver_match_device() can call cdx_bus_match() from __driver_attach() without holding the device lock, and cdx_bus_match() still dereferences that private pointer directly. That means the CDX match path can race with a concurrent driver_override update and compare against freed memory. Switch CDX to the driver-core driver_override infrastructure. This removes the private driver_override storage, lets the core provide the sysfs attribute, and uses device_match_driver_override() for the locked read in cdx_bus_match(). Preserve the existing CDX override_only semantics: entries marked override_only still require a matching driver_override, but ordinary ID matches continue to work unchanged. Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel.org/ (local) Fixes: 48a6c7bced2a ("cdx: add device attributes") Cc: stable@vger.kernel.org Signed-off-by: Runyu Xiao <redacted> --- drivers/cdx/cdx.c | 40 +++++-------------------------------- include/linux/cdx/cdx_bus.h | 1 - 2 files changed, 5 insertions(+), 36 deletions(-)
diff --git a/drivers/cdx/cdx.c b/drivers/cdx/cdx.c
index 9196dc50a48d..d3d230247262 100644
--- a/drivers/cdx/cdx.c
+++ b/drivers/cdx/cdx.c@@ -156,8 +156,6 @@ static int cdx_unregister_device(struct device *dev, } else { cdx_destroy_res_attr(cdx_dev, MAX_CDX_DEV_RESOURCES); debugfs_remove_recursive(cdx_dev->debugfs_dir); - kfree(cdx_dev->driver_override); - cdx_dev->driver_override = NULL; } /*
@@ -268,6 +266,7 @@ static int cdx_bus_match(struct device *dev, const struct device_driver *drv) const struct cdx_driver *cdx_drv = to_cdx_driver(drv); const struct cdx_device_id *found_id = NULL; const struct cdx_device_id *ids; + int ret; if (cdx_dev->is_bus) return false;
@@ -275,7 +274,8 @@ static int cdx_bus_match(struct device *dev, const struct device_driver *drv) ids = cdx_drv->match_id_table; /* When driver_override is set, only bind to the matching driver */ - if (cdx_dev->driver_override && strcmp(cdx_dev->driver_override, drv->name)) + ret = device_match_driver_override(dev, drv); + if (ret == 0) return false; found_id = cdx_match_id(ids, cdx_dev);
@@ -289,7 +289,7 @@ static int cdx_bus_match(struct device *dev, const struct device_driver *drv) */ if (!found_id->override_only) return true; - if (cdx_dev->driver_override) + if (ret > 0) return true; ids = found_id + 1;
@@ -453,36 +453,6 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, } static DEVICE_ATTR_RO(modalias); -static ssize_t driver_override_store(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) -{ - struct cdx_device *cdx_dev = to_cdx_device(dev); - int ret; - - if (WARN_ON(dev->bus != &cdx_bus_type)) - return -EINVAL; - - ret = driver_set_override(dev, &cdx_dev->driver_override, buf, count); - if (ret) - return ret; - - return count; -} - -static ssize_t driver_override_show(struct device *dev, - struct device_attribute *attr, char *buf) -{ - struct cdx_device *cdx_dev = to_cdx_device(dev); - ssize_t len; - - device_lock(dev); - len = sysfs_emit(buf, "%s\n", cdx_dev->driver_override); - device_unlock(dev); - return len; -} -static DEVICE_ATTR_RW(driver_override); - static ssize_t enable_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) {
@@ -552,7 +522,6 @@ static struct attribute *cdx_dev_attrs[] = { &dev_attr_class.attr, &dev_attr_revision.attr, &dev_attr_modalias.attr, - &dev_attr_driver_override.attr, NULL, };
@@ -646,6 +615,7 @@ ATTRIBUTE_GROUPS(cdx_bus); const struct bus_type cdx_bus_type = { .name = "cdx", + .driver_override = true, .match = cdx_bus_match, .probe = cdx_probe, .remove = cdx_remove,
diff --git a/include/linux/cdx/cdx_bus.h b/include/linux/cdx/cdx_bus.h
index b1ba97f6c9ad..f1a107b232da 100644
--- a/include/linux/cdx/cdx_bus.h
+++ b/include/linux/cdx/cdx_bus.h@@ -165,7 +165,6 @@ struct cdx_device { bool enabled; u32 msi_dev_id; u32 num_msi; - const char *driver_override; struct mutex irqchip_lock; bool msi_write_pending; };
--
2.34.1