Re: [PATCH V1 3/3] rpmsg: glink: Add lock for ctrl device

Bjorn Andersson
2022-03-11T20:55:06Z

On Wed 26 Jan 13:04 CST 2022, Deepak Kumar Singh wrote:

> Race between rpmsg_eptdev_create and rpmsg_chrdev_remove
> can sometime casue crash while accessing rpdev while new
> endpoint is being created. Using lock ensure no new eptdev
> is created after rpmsg_chrdev_remove has been completed.

This patch lacks a Signed-off-by.

Isn't this solving the same problem as the previous patch? Would be nice
with some more specifics on the race that you're seeing.

Thanks,
Bjorn

> ---
> drivers/rpmsg/rpmsg_char.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index 2108ef8..3e5b85d 100644
> --- a/drivers/rpmsg/rpmsg_char.c
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -27,6 +27,7 @@
>
> static dev_t rpmsg_major;
> static struct class *rpmsg_class;
> +struct mutex ctrl_lock;
>
> static DEFINE_IDA(rpmsg_ctrl_ida);
> static DEFINE_IDA(rpmsg_ept_ida);
> @@ -396,9 +397,12 @@ static int rpmsg_eptdev_create(struct rpmsg_ctrldev *ctrldev,
> struct device *dev;
> int ret;
>
> + mutex_lock(&ctrl_lock);
> eptdev = kzalloc(sizeof(*eptdev), GFP_KERNEL);
> - if (!eptdev)
> + if (!eptdev) {
> + mutex_unlock(&ctrl_lock);
> return -ENOMEM;
> + }
>
> dev = &eptdev->dev;
> eptdev->rpdev = rpdev;
> @@ -443,6 +447,7 @@ static int rpmsg_eptdev_create(struct rpmsg_ctrldev *ctrldev,
> put_device(dev);
> }
>
> + mutex_unlock(&ctrl_lock);
> return ret;
>
> free_ept_ida:
> @@ -453,6 +458,7 @@ static int rpmsg_eptdev_create(struct rpmsg_ctrldev *ctrldev,
> put_device(dev);
> kfree(eptdev);
>
> + mutex_unlock(&ctrl_lock);
> return ret;
> }
>
> @@ -525,6 +531,7 @@ static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
> if (!ctrldev)
> return -ENOMEM;
>
> + mutex_init(&ctrl_lock);
> ctrldev->rpdev = rpdev;
>
> dev = &ctrldev->dev;
> @@ -581,12 +588,14 @@ static void rpmsg_chrdev_remove(struct rpmsg_device *rpdev)
> int ret;
>
> /* Destroy all endpoints */
> + mutex_lock(&ctrl_lock);
> ret = device_for_each_child(&ctrldev->dev, NULL, rpmsg_eptdev_destroy);
> if (ret)
> dev_warn(&rpdev->dev, "failed to nuke endpoints: %d\n", ret);
>
> device_del(&ctrldev->dev);
> put_device(&ctrldev->dev);
> + mutex_unlock(&ctrl_lock);
> }
>
> static struct rpmsg_driver rpmsg_chrdev_driver = {
> --
> 2.7.4
>