[PATCH] rpmsg: virtio: fix error handling in TX buffer wait

[PATCH] rpmsg: virtio: fix error handling in TX buffer wait

[Atul Akella]

The TX buffer wait loop in rpmsg_send_offchannel_raw() ignores the
possibility of wait_event_interruptible_timeout() returning a
negative value, which happens when the wait is interrupted by a
signal. In that case the loop spins back around and re-arms the
wait instead of propagating the signal, which can stall a task
that is trying to be killed.

Separately, on a genuine timeout (return value 0) the function
returns -ERESTARTSYS, which is reserved for signal-interrupted
syscalls that the kernel may restart. A timeout is not a signal
and should not be treated as restartable; return -ETIMEDOUT
instead.

Handle both cases explicitly: return err directly when negative,
and return -ETIMEDOUT on timeout.

Fixes: bcabbccabffe ("rpmsg: add virtio-based remote processor messaging bus")
Signed-off-by: Atul Akella <atul.akella@gmail.com>
---
 drivers/rpmsg/virtio_rpmsg_bus.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
index 1b8bb05924af..a32772d6ccbc 100644
--- a/drivers/rpmsg/virtio_rpmsg_bus.c
+++ b/drivers/rpmsg/virtio_rpmsg_bus.c
@@ -536,10 +536,13 @@ static int rpmsg_send_offchannel_raw(struct rpmsg_device *rpdev,
 					(msg = get_a_tx_buf(vrp)),
 					msecs_to_jiffies(15000));
 
+		if (err < 0)
+			return err;
+
 		/* timeout ? */
 		if (!err) {
 			dev_err(dev, "timeout waiting for a tx buffer\n");
-			return -ERESTARTSYS;
+			return -ETIMEDOUT;
 		}
 	}
 
-- 
2.51.0.windows.1

Re: [PATCH] rpmsg: virtio: fix error handling in TX buffer wait

[Mathieu Poirier]

On Tue, Oct 13, 2026 at 09:30:55PM +0530, Atul Akella wrote:
> The TX buffer wait loop in rpmsg_send_offchannel_raw() ignores the
> possibility of wait_event_interruptible_timeout() returning a
> negative value, which happens when the wait is interrupted by a
> signal. In that case the loop spins back around and re-arms the
> wait instead of propagating the signal, which can stall a task
> that is trying to be killed.
> 
> Separately, on a genuine timeout (return value 0) the function
> returns -ERESTARTSYS, which is reserved for signal-interrupted
> syscalls that the kernel may restart. A timeout is not a signal
> and should not be treated as restartable; return -ETIMEDOUT
> instead.
> 
> Handle both cases explicitly: return err directly when negative,
> and return -ETIMEDOUT on timeout.
> 
> Fixes: bcabbccabffe ("rpmsg: add virtio-based remote processor messaging bus")
> Signed-off-by: Atul Akella <atul.akella@gmail.com>
> ---
>  drivers/rpmsg/virtio_rpmsg_bus.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
> index 1b8bb05924af..a32772d6ccbc 100644
> --- a/drivers/rpmsg/virtio_rpmsg_bus.c
> +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
> @@ -536,10 +536,13 @@ static int rpmsg_send_offchannel_raw(struct rpmsg_device *rpdev,
>  					(msg = get_a_tx_buf(vrp)),
>  					msecs_to_jiffies(15000));
>  
> +		if (err < 0)
> +			return err;
> +
>  		/* timeout ? */
>  		if (!err) {
>  			dev_err(dev, "timeout waiting for a tx buffer\n");
> -			return -ERESTARTSYS;
> +			return -ETIMEDOUT;

Applied.

Thanks,
Mathieu

>  		}
>  	}
>  
> -- 
> 2.51.0.windows.1
>