[PATCH v2 2/4] rpmsg: core: use generic driver_override infrastructure
From: Runyu Xiao <hidden>
Date: 2026-06-04 03:52:58
Also in:
driver-core, linux-arm-msm, linux-remoteproc, lkml, stable
Subsystem:
arm/qualcomm mailing list, remote processor messaging (rpmsg) subsystem, the rest · Maintainers:
Bjorn Andersson, Mathieu Poirier, Linus Torvalds
RPMSG still keeps driver_override in bus-private storage. That private pointer can be updated from the sysfs driver_override attribute, and also from rpmsg_register_device_override(). Both paths replace the pointer and can free the old value. However, driver_match_device() can call rpmsg_dev_match() from __driver_attach() without holding the device lock, and rpmsg_dev_match() still dereferences that private pointer directly. This leaves the match path racing with concurrent driver_override updates, with the usual risk of comparing against freed memory. Switch rpmsg to the driver-core driver_override infrastructure. This removes the private storage, uses device_match_driver_override() for the locked read in rpmsg_dev_match(), and converts rpmsg_register_device_override() to device_set_driver_override() so the in-kernel override path uses the same core-managed storage. With that storage now owned by struct device, drop the remaining rpmsg transport release-path frees of rpdev->driver_override as well. Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel.org/ (local) Fixes: 39e47767ec9b ("rpmsg: Add driver_override device attribute for rpmsg_device") Cc: stable@vger.kernel.org Signed-off-by: Runyu Xiao <redacted> --- drivers/rpmsg/qcom_glink_native.c | 2 -- drivers/rpmsg/rpmsg_core.c | 41 ++++++-------------------------------- drivers/rpmsg/virtio_rpmsg_bus.c | 1 - include/linux/rpmsg.h | 4 ---- 4 files changed, 6 insertions(+), 42 deletions(-)
diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
index e7f7831d37f8..11d3007db5cd 100644
--- a/drivers/rpmsg/rpmsg_core.c
+++ b/drivers/rpmsg/rpmsg_core.c@@ -358,33 +358,6 @@ rpmsg_show_attr(src, src, "0x%x\n"); rpmsg_show_attr(dst, dst, "0x%x\n"); rpmsg_show_attr(announce, announce ? "true" : "false", "%s\n"); -static ssize_t driver_override_store(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) -{ - struct rpmsg_device *rpdev = to_rpmsg_device(dev); - int ret; - - ret = driver_set_override(dev, &rpdev->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 rpmsg_device *rpdev = to_rpmsg_device(dev); - ssize_t len; - - device_lock(dev); - len = sysfs_emit(buf, "%s\n", rpdev->driver_override); - device_unlock(dev); - return len; -} -static DEVICE_ATTR_RW(driver_override); - static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, char *buf) {
@@ -405,7 +378,6 @@ static struct attribute *rpmsg_dev_attrs[] = { &dev_attr_dst.attr, &dev_attr_src.attr, &dev_attr_announce.attr, - &dev_attr_driver_override.attr, NULL, }; ATTRIBUTE_GROUPS(rpmsg_dev);
@@ -424,9 +396,11 @@ static int rpmsg_dev_match(struct device *dev, const struct device_driver *drv) const struct rpmsg_driver *rpdrv = to_rpmsg_driver(drv); const struct rpmsg_device_id *ids = rpdrv->id_table; unsigned int i; + int ret; - if (rpdev->driver_override) - return !strcmp(rpdev->driver_override, drv->name); + ret = device_match_driver_override(dev, drv); + if (ret >= 0) + return ret; if (ids) for (i = 0; ids[i].name[0]; i++)
@@ -533,6 +507,7 @@ static void rpmsg_dev_remove(struct device *dev) static const struct bus_type rpmsg_bus = { .name = "rpmsg", + .driver_override = true, .match = rpmsg_dev_match, .dev_groups = rpmsg_dev_groups, .uevent = rpmsg_uevent,
@@ -560,9 +535,7 @@ int rpmsg_register_device_override(struct rpmsg_device *rpdev, device_initialize(dev); if (driver_override) { - ret = driver_set_override(dev, &rpdev->driver_override, - driver_override, - strlen(driver_override)); + ret = device_set_driver_override(dev, driver_override); if (ret) { dev_err(dev, "device_set_override failed: %d\n", ret); put_device(dev);
@@ -573,8 +546,6 @@ int rpmsg_register_device_override(struct rpmsg_device *rpdev, ret = device_add(dev); if (ret) { dev_err(dev, "device_add failed: %d\n", ret); - kfree(rpdev->driver_override); - rpdev->driver_override = NULL; put_device(dev); }
diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
index 401a4ece0c97..d9d4468e4cbd 100644
--- a/drivers/rpmsg/qcom_glink_native.c
+++ b/drivers/rpmsg/qcom_glink_native.c@@ -1626,7 +1626,6 @@ static void qcom_glink_rpdev_release(struct device *dev) { struct rpmsg_device *rpdev = to_rpmsg_device(dev); - kfree(rpdev->driver_override); kfree(rpdev); }
@@ -1862,7 +1861,6 @@ static void qcom_glink_device_release(struct device *dev) /* Release qcom_glink_alloc_channel() reference */ kref_put(&channel->refcount, qcom_glink_channel_release); - kfree(rpdev->driver_override); kfree(rpdev); }
diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
index 5ae15111fb4f..1b8bb05924af 100644
--- a/drivers/rpmsg/virtio_rpmsg_bus.c
+++ b/drivers/rpmsg/virtio_rpmsg_bus.c@@ -374,7 +374,6 @@ static void virtio_rpmsg_release_device(struct device *dev) struct rpmsg_device *rpdev = to_rpmsg_device(dev); struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev); - kfree(rpdev->driver_override); kfree(vch); }
diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
index 83266ce14642..2e40eb54155e 100644
--- a/include/linux/rpmsg.h
+++ b/include/linux/rpmsg.h@@ -41,9 +41,6 @@ struct rpmsg_channel_info { * rpmsg_device - device that belong to the rpmsg bus * @dev: the device struct * @id: device id (used to match between rpmsg drivers and devices) - * @driver_override: driver name to force a match; do not set directly, - * because core frees it; use driver_set_override() to - * set or clear it. * @src: local address * @dst: destination address * @ept: the rpmsg endpoint of this channel
@@ -53,7 +50,6 @@ struct rpmsg_channel_info { struct rpmsg_device { struct device dev; struct rpmsg_device_id id; - const char *driver_override; u32 src; u32 dst; struct rpmsg_endpoint *ept;
--
2.34.1