[PATCH 6.12.y 1/3] serial: introduce uart_port_lock() guard()s

[Sasha Levin <sashal@kernel.org>]

From: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>

[ Upstream commit 0fd60b689b0dacce659253ec15cb3d3bf660e30b ]

Having this, guards like these work:
  guard(uart_port_lock_irq)(&up->port);
or
  scoped_guard(uart_port_lock_irqsave, port) {
    ...
  }

See e.g. "serial: 8250: use guard()s" later in this series.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250814072456.182853-4-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 8ca59f7baee7 ("serial: fix ioctl hangup race")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/serial_core.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 4ab65874a850b..191154b8ada2a 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -782,6 +782,19 @@ static inline void uart_port_unlock_irqrestore(struct uart_port *up, unsigned lo
 	spin_unlock_irqrestore(&up->lock, flags);
 }
 
+DEFINE_GUARD(uart_port_lock, struct uart_port *, uart_port_lock(_T), uart_port_unlock(_T));
+DEFINE_GUARD_COND(uart_port_lock, _try, uart_port_trylock(_T));
+
+DEFINE_GUARD(uart_port_lock_irq, struct uart_port *, uart_port_lock_irq(_T),
+	     uart_port_unlock_irq(_T));
+
+DEFINE_LOCK_GUARD_1(uart_port_lock_irqsave, struct uart_port,
+                    uart_port_lock_irqsave(_T->lock, &_T->flags),
+                    uart_port_unlock_irqrestore(_T->lock, _T->flags),
+                    unsigned long flags);
+DEFINE_LOCK_GUARD_1_COND(uart_port_lock_irqsave, _try,
+			 uart_port_trylock_irqsave(_T->lock, &_T->flags));
+
 static inline int serial_port_in(struct uart_port *up, int offset)
 {
 	return up->serial_in(up, offset);
-- 
2.53.0