From 68aa2c0d4a36b43ea9c6d77134c94b4501fd2eb4 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Fri, 30 Jun 2006 02:29:59 -0700 Subject: [PATCH] [SERIAL] 8250: sysrq deadlock fix Fix http://bugzilla.kernel.org/show_bug.cgi?id=6716 Doing a sysrq over a serial line into an SMP machine presently deadlocks. Signed-off-by: Andrew Morton Signed-off-by: Russell King --- drivers/serial/8250.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c index 5443fcd3835..0ae9ced00ed 100644 --- a/drivers/serial/8250.c +++ b/drivers/serial/8250.c @@ -2252,10 +2252,14 @@ serial8250_console_write(struct console *co, const char *s, unsigned int count) touch_nmi_watchdog(); - if (oops_in_progress) { - locked = spin_trylock_irqsave(&up->port.lock, flags); + local_irq_save(flags); + if (up->port.sysrq) { + /* serial8250_handle_port() already took the lock */ + locked = 0; + } else if (oops_in_progress) { + locked = spin_trylock(&up->port.lock); } else - spin_lock_irqsave(&up->port.lock, flags); + spin_lock(&up->port.lock); /* * First save the IER then disable the interrupts @@ -2277,7 +2281,8 @@ serial8250_console_write(struct console *co, const char *s, unsigned int count) serial_out(up, UART_IER, ier); if (locked) - spin_unlock_irqrestore(&up->port.lock, flags); + spin_unlock(&up->port.lock); + local_irq_restore(flags); } static int serial8250_console_setup(struct console *co, char *options) -- 2.46.0