Re: [PATCH 3/5] rpmsg: Add TIOCMGET/TIOCMSET ioctl support

Bjorn Andersson
2018-10-04T00:54:33Z

On Wed 03 Oct 04:34 PDT 2018, Arun Kumar Neelakantam wrote:

> Add TICOMGET and TIOCMSET ioctl support for rpmsg char device nodes
> to get/set the low level transport signals.
>
> Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
> ---
> drivers/rpmsg/rpmsg_char.c | 54 +++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 51 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index 86003d5..c983d6c 100644
> --- a/drivers/rpmsg/rpmsg_char.c
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -20,6 +20,7 @@
> #include <linux/rpmsg.h>
> #include <linux/skbuff.h>
> #include <linux/slab.h>
> +#include <linux/termios.h>
> #include <linux/uaccess.h>
> #include <uapi/linux/rpmsg.h>
>
> @@ -274,15 +275,62 @@ static __poll_t rpmsg_eptdev_poll(struct file *filp, poll_table *wait)
> return mask;
> }
>
> +static int rpmsg_eptdev_tiocmset(struct file *fp, unsigned int cmd,
> + unsigned long arg)

Make arg type int __user *

> +{
> + struct rpmsg_eptdev *eptdev = fp->private_data;
> + u32 lsigs, rsigs, val;
> + int ret;
> +
> + ret = get_user(val, (u32 *)arg);
> + if (ret)
> + return ret;
> +
> + ret = rpmsg_get_sigs(eptdev->ept, &lsigs, &rsigs);
> + if (ret < 0)
> + return ret;
> +
> + switch (cmd) {
> + case TIOCMBIS:
> + lsigs |= val;
> + break;
> + case TIOCMBIC:
> + lsigs &= ~val;
> + break;
> + case TIOCMSET:
> + lsigs = val;
> + break;
> + }
> +
> + ret = rpmsg_set_sigs(eptdev->ept, lsigs);

This is racy, as the signals might change while we update them. Mimic
tty_tiocmset() instead and make rpmsg_set_sigs() take a clear and set
mask.

And please do spell out rpmsg_set_signal() and rpmsg_get_signal().

> + return ret;

return rpmsg_set_signals();

> +}
> +
> static long rpmsg_eptdev_ioctl(struct file *fp, unsigned int cmd,
> unsigned long arg)
> {
> struct rpmsg_eptdev *eptdev = fp->private_data;
> + u32 lsigs, rsigs;
> + int ret;
>
> - if (cmd != RPMSG_DESTROY_EPT_IOCTL)
> - return -EINVAL;
> + switch (cmd) {
> + case TIOCMGET:
> + ret = rpmsg_get_sigs(eptdev->ept, &lsigs, &rsigs);
> + if (!ret)
> + ret = put_user(rsigs, (u32 *)arg);

Cast to int __user *

> + break;
> + case TIOCMSET:
> + case TIOCMBIS:
> + case TIOCMBIC:
> + ret = rpmsg_eptdev_tiocmset(fp, cmd, arg);
> + break;
> + case RPMSG_DESTROY_EPT_IOCTL:
> + ret = rpmsg_eptdev_destroy(&eptdev->dev, NULL);
> + default:
> + ret = -EINVAL;
> + }
>
> - return rpmsg_eptdev_destroy(&eptdev->dev, NULL);
> + return ret;
> }

Regards,
Bjorn