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Date: Fri, 29 Apr 2022 23:56:56 +0200
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Mathieu Poirier <mathieu.poirier@...aro.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] rpmsg: Fix calling device_lock() on non-initialized
device
On 29.04.2022 21:59, Krzysztof Kozlowski wrote:
> driver_set_override() helper uses device_lock() so it should not be
> called before rpmsg_register_device() (which calls device_register()).
> Effect can be seen with CONFIG_DEBUG_MUTEXES:
>
> DEBUG_LOCKS_WARN_ON(lock->magic != lock)
> WARNING: CPU: 3 PID: 57 at kernel/locking/mutex.c:582 __mutex_lock+0x1ec/0x430
> ...
> Call trace:
> __mutex_lock+0x1ec/0x430
> mutex_lock_nested+0x44/0x50
> driver_set_override+0x124/0x150
> qcom_glink_native_probe+0x30c/0x3b0
> glink_rpm_probe+0x274/0x350
> platform_probe+0x6c/0xe0
> really_probe+0x17c/0x3d0
> __driver_probe_device+0x114/0x190
> driver_probe_device+0x3c/0xf0
> ...
>
> Refactor the rpmsg_register_device() function to use two-step device
> registering (initialization + add) and call driver_set_override() in
> proper moment.
>
> This moves the code around, so while at it also NULL-ify the
> rpdev->driver_override in error path to be sure it won't be kfree()
> second time.
>
> Fixes: 42cd402b8fd4 ("rpmsg: Fix kfree() of static memory on setting driver_override")
> Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
>
> Commit SHA from linux-next - Greg's tree.
> ---
> drivers/rpmsg/rpmsg_core.c | 33 ++++++++++++++++++++++++++++++---
> drivers/rpmsg/rpmsg_internal.h | 14 +-------------
> drivers/rpmsg/rpmsg_ns.c | 14 +-------------
> include/linux/rpmsg.h | 8 ++++++++
> 4 files changed, 40 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index 95fc283f6af7..4938fc4eff00 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -593,24 +593,51 @@ static struct bus_type rpmsg_bus = {
> .remove = rpmsg_dev_remove,
> };
>
> -int rpmsg_register_device(struct rpmsg_device *rpdev)
> +/*
> + * A helper for registering rpmsg device with driver override and name.
> + * Drivers should not be using it, but instead rpmsg_register_device().
> + */
> +int rpmsg_register_device_override(struct rpmsg_device *rpdev,
> + const char *driver_override)
> {
> struct device *dev = &rpdev->dev;
> int ret;
>
> + if (driver_override)
> + strcpy(rpdev->id.name, driver_override);
> +
> dev_set_name(&rpdev->dev, "%s.%s.%d.%d", dev_name(dev->parent),
> rpdev->id.name, rpdev->src, rpdev->dst);
>
> rpdev->dev.bus = &rpmsg_bus;
>
> - ret = device_register(&rpdev->dev);
> + device_initialize(dev);
> + if (driver_override) {
> + ret = driver_set_override(dev, &rpdev->driver_override,
> + driver_override,
> + strlen(driver_override));
> + if (ret) {
> + dev_err(dev, "device_set_override failed: %d\n", ret);
> + return ret;
> + }
> + }
> +
> + ret = device_add(dev);
> if (ret) {
> - dev_err(dev, "device_register failed: %d\n", ret);
> + dev_err(dev, "device_add failed: %d\n", ret);
> + kfree(rpdev->driver_override);
> + rpdev->driver_override = NULL;
> put_device(&rpdev->dev);
> }
>
> return ret;
> }
> +EXPORT_SYMBOL(rpmsg_register_device_override);
> +
> +int rpmsg_register_device(struct rpmsg_device *rpdev)
> +{
> + return rpmsg_register_device_override(rpdev, NULL);
> +}
> EXPORT_SYMBOL(rpmsg_register_device);
>
> /*
> diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
> index 3e81642238d2..a22cd4abe7d1 100644
> --- a/drivers/rpmsg/rpmsg_internal.h
> +++ b/drivers/rpmsg/rpmsg_internal.h
> @@ -94,19 +94,7 @@ int rpmsg_release_channel(struct rpmsg_device *rpdev,
> */
> static inline int rpmsg_ctrldev_register_device(struct rpmsg_device *rpdev)
> {
> - int ret;
> -
> - strcpy(rpdev->id.name, "rpmsg_ctrl");
> - ret = driver_set_override(&rpdev->dev, &rpdev->driver_override,
> - rpdev->id.name, strlen(rpdev->id.name));
> - if (ret)
> - return ret;
> -
> - ret = rpmsg_register_device(rpdev);
> - if (ret)
> - kfree(rpdev->driver_override);
> -
> - return ret;
> + return rpmsg_register_device_override(rpdev, "rpmsg_ctrl");
> }
>
> #endif
> diff --git a/drivers/rpmsg/rpmsg_ns.c b/drivers/rpmsg/rpmsg_ns.c
> index 8eb8f328237e..c70ad03ff2e9 100644
> --- a/drivers/rpmsg/rpmsg_ns.c
> +++ b/drivers/rpmsg/rpmsg_ns.c
> @@ -20,22 +20,10 @@
> */
> int rpmsg_ns_register_device(struct rpmsg_device *rpdev)
> {
> - int ret;
> -
> - strcpy(rpdev->id.name, "rpmsg_ns");
> - ret = driver_set_override(&rpdev->dev, &rpdev->driver_override,
> - rpdev->id.name, strlen(rpdev->id.name));
> - if (ret)
> - return ret;
> -
> rpdev->src = RPMSG_NS_ADDR;
> rpdev->dst = RPMSG_NS_ADDR;
>
> - ret = rpmsg_register_device(rpdev);
> - if (ret)
> - kfree(rpdev->driver_override);
> -
> - return ret;
> + return rpmsg_register_device_override(rpdev, "rpmsg_ns");
> }
> EXPORT_SYMBOL(rpmsg_ns_register_device);
>
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> index 20c8cd1cde21..523c98b96cb4 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -165,6 +165,8 @@ static inline __rpmsg64 cpu_to_rpmsg64(struct rpmsg_device *rpdev, u64 val)
>
> #if IS_ENABLED(CONFIG_RPMSG)
>
> +int rpmsg_register_device_override(struct rpmsg_device *rpdev,
> + const char *driver_override);
> int rpmsg_register_device(struct rpmsg_device *rpdev);
> int rpmsg_unregister_device(struct device *parent,
> struct rpmsg_channel_info *chinfo);
> @@ -192,6 +194,12 @@ ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept);
>
> #else
>
> +static inline int rpmsg_register_device_override(struct rpmsg_device *rpdev,
> + const char *driver_override)
> +{
> + return -ENXIO;
> +}
> +
> static inline int rpmsg_register_device(struct rpmsg_device *rpdev)
> {
> return -ENXIO;
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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