From 4bf3631cdb012591667ab927fcd7719d92837833 Mon Sep 17 00:00:00 2001 From: Jiri Kosina Date: Mon, 23 Apr 2007 14:41:21 -0700 Subject: [PATCH] 8250: fix possible deadlock between serial8250_handle_port() and serial8250_interrupt() Commit 40b36daa introduced possibility that serial8250_backup_timeout() -> serial8250_handle_port() locks port.lock without disabling irqs, thus allowing deadlock against interrupt handler (port.lock is acquired in serial8250_interrupt()). Spotted by lockdep. Signed-off-by: Jiri Kosina Cc: Dave Jones Cc: Russell King Cc: Alex Williamson Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/serial/8250.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c index c0c472ac531..90621c3312b 100644 --- a/drivers/serial/8250.c +++ b/drivers/serial/8250.c @@ -1334,8 +1334,9 @@ static inline void serial8250_handle_port(struct uart_8250_port *up) { unsigned int status; + unsigned long flags; - spin_lock(&up->port.lock); + spin_lock_irqsave(&up->port.lock, flags); status = serial_inp(up, UART_LSR); @@ -1347,7 +1348,7 @@ serial8250_handle_port(struct uart_8250_port *up) if (status & UART_LSR_THRE) transmit_chars(up); - spin_unlock(&up->port.lock); + spin_unlock_irqrestore(&up->port.lock, flags); } /* -- 2.41.1