On Fri, Oct 16, 2026 at 06:00:32PM +0000, Markus Probst wrote:
Besides more predictable behaviour, this allows for several hardened behaviour changes:
Return -EALREADY in `serdev_device_open` if the device is already open instead of causing undefined behaviour.
Allow calling `serdev_device_close`, even if the device is already closed instead of causing a null pointer dereference.
If the device is left open by the driver after remove, close it and warn instead of leaving it in a invalid state.
Signed-off-by: Markus Probst markus.probst@posteo.de
drivers/tty/serdev/core.c | 10 +++++--- drivers/tty/serdev/serdev-ttyport.c | 46 +++++++++++++++++++++++++++++++------ include/linux/serdev.h | 2 +- 3 files changed, 47 insertions(+), 11 deletions(-)
diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c index 7500efcdfc21..77e8e1d4d2a6 100644 --- a/drivers/tty/serdev/core.c +++ b/drivers/tty/serdev/core.c @@ -142,6 +142,11 @@ void serdev_device_remove(struct serdev_device *serdev) struct serdev_controller *ctrl = serdev->ctrl; device_unregister(&serdev->dev);
- /* Warn if driver did not close the serial device. */
- if (ctrl->ops->close && WARN_ON(ctrl->ops->close(ctrl)))
I understand the want to give a big "splat" if this happens, but if it does somehow, you just crashed the box due to panic-on-warn, which will result in a CVE being given :)
So, if this ever can happen, we should recover like you do:
pm_runtime_put(&ctrl->dev);
And you can warn about it in the kernel log, but just not with WARN_ON() please.
thanks,
greg k-h