6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Francesco Dolcini <francesco.dolcini@xxxxxxxxxxx>
commit c8820c92caf0770bec976b01fa9e82bb993c5865 upstream.
Serdev recv_buf() callback is supposed to return the amount of bytes
consumed, therefore an int in between 0 and count.
Do not return negative number in case of issue, when
ssam_controller_receive_buf() returns ESHUTDOWN just returns 0, e.g. no
bytes consumed, this keep the exact same behavior as it was before.
This fixes a potential WARN in serdev-ttyport.c:ttyport_receive_buf().
Fixes: c167b9c7e3d6 ("platform/surface: Add Surface Aggregator subsystem")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Francesco Dolcini <francesco.dolcini@xxxxxxxxxxx>
Reviewed-by: Maximilian Luz <luzmaximilian@xxxxxxxxx>
Link: https://lore.kernel.org/r/20231128194935.11350-1-francesco@xxxxxxxxxx
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/platform/surface/aggregator/core.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/platform/surface/aggregator/core.c
+++ b/drivers/platform/surface/aggregator/core.c
@@ -231,9 +231,12 @@ static int ssam_receive_buf(struct serde
size_t n)
{
struct ssam_controller *ctrl;
+ int ret;
ctrl = serdev_device_get_drvdata(dev);
- return ssam_controller_receive_buf(ctrl, buf, n);
+ ret = ssam_controller_receive_buf(ctrl, buf, n);
+
+ return ret < 0 ? 0 : ret;
}
static void ssam_write_wakeup(struct serdev_device *dev)
