[PATCH 6.18 551/869] serial: pmac_zilog: push received data to the port that received it

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tim Douglas <me@timdoug.com>

[ Upstream commit f3dc727da3af64abc12b625bbf1eb68d55d882cc ]

pmz_interrupt() drains both channels but, since commit 2e124b4a390c
("TTY: switch tty_flip_buffer_push"), pushes the flip buffer of the
port whose handler is running rather than the port that was drained.
With both ports open, data received on the other port can be left in
its flip buffer until something else pushes it, so its reader may not
see it.

Fixes: 2e124b4a390c ("TTY: switch tty_flip_buffer_push")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: Tim Douglas <me@timdoug.com>
Link: https://patch.msgid.link/20261013013541.4535-2-me@timdoug.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/tty/serial/pmac_zilog.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/pmac_zilog.c b/drivers/tty/serial/pmac_zilog.c
index e3a9193286954..f49d6052d11be 100644
--- a/drivers/tty/serial/pmac_zilog.c
+++ b/drivers/tty/serial/pmac_zilog.c
@@ -444,7 +444,7 @@ static irqreturn_t pmz_interrupt(int irq, void *dev_id)
  skip_a:
 	uart_port_unlock(&uap_a->port);
 	if (push)
-		tty_flip_buffer_push(&uap->port.state->port);
+		tty_flip_buffer_push(&uap_a->port.state->port);
 
 	if (!uap_b)
 		goto out;
@@ -469,7 +469,7 @@ static irqreturn_t pmz_interrupt(int irq, void *dev_id)
  skip_b:
 	uart_port_unlock(&uap_b->port);
 	if (push)
-		tty_flip_buffer_push(&uap->port.state->port);
+		tty_flip_buffer_push(&uap_b->port.state->port);
 
  out:
 	return rc;
-- 
2.53.0