From e1dd3bef6d03c908b173259229b96074d57fccc8 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Fri, 27 Nov 2015 11:13:48 +0100 Subject: [PATCH] serial: earlycon: Add missing spinlock initialization If an earlycon console driver needs to acquire the uart_port.lock spinlock for serial console output, and CONFIG_DEBUG_SPINLOCK=y: BUG: spinlock bad magic on CPU#0, swapper/0 lock: sci_ports+0x0/0x3480, .magic: 00000000, .owner: /-1, .owner_cpu: 0 CPU: 0 PID: 0 Comm: swapper Not tainted 4.4.0-rc2-koelsch-g62ea5edf143bb1d0-dirty #2083 Hardware name: Generic R8A7791 (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0x70/0x8c) [] (dump_stack) from [] (do_raw_spin_lock+0x20/0x190) [] (do_raw_spin_lock) from [] (serial_console_write+0x4c/0x130) [] (serial_console_write) from [] (call_console_drivers.constprop.13+0xc8/0xec) [] (call_console_drivers.constprop.13) from [] (console_unlock+0x354/0x440) [] (console_unlock) from [] (register_console+0x2a0/0x394) [] (register_console) from [] (of_setup_earlycon+0x90/0xa4) [] (of_setup_earlycon) from [] (setup_of_earlycon+0x118/0x13c) [] (setup_of_earlycon) from [] (do_early_param+0x64/0xb4) [] (do_early_param) from [] (parse_args+0x254/0x350) [] (parse_args) from [] (parse_early_options+0x2c/0x3c) [] (parse_early_options) from [] (parse_early_param+0x2c/0x40) [] (parse_early_param) from [] (setup_arch+0x520/0xaf0) [] (setup_arch) from [] (start_kernel+0x94/0x370) [] (start_kernel) from [<40008090>] (0x40008090) Initialize the spinlock in of_setup_earlycon() and register_earlycon(), to fix this for both DT-based and legacy earlycon. If the driver would reinitialize the spinlock again, this is harmless, as it's allowed to reinitialize an unlocked spinlock. Alternatives are: - Drivers having an early_serial_console_write() that only performs the core functionality of serial_console_write(), without acquiring the lock (which may be unsafe, depending on the hardware), - Drivers initializing the spinlock in their private earlycon setup functions. As uart_port is owned by generic serial_core, and uart_port.lock is initialized by uart_add_one_port() for the normal case, this can better be handled in the earlycon core. Signed-off-by: Geert Uytterhoeven Reviewed-by: Peter Hurley Reported-by: Bjorn Andersson Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/earlycon.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c index f09636083426..b5b2f2be6be7 100644 --- a/drivers/tty/serial/earlycon.c +++ b/drivers/tty/serial/earlycon.c @@ -115,6 +115,7 @@ static int __init register_earlycon(char *buf, const struct earlycon_id *match) if (buf && !parse_options(&early_console_dev, buf)) buf = NULL; + spin_lock_init(&port->lock); port->uartclk = BASE_BAUD * 16; if (port->mapbase) port->membase = earlycon_map(port->mapbase, 64); @@ -202,6 +203,7 @@ int __init of_setup_earlycon(unsigned long addr, int err; struct uart_port *port = &early_console_dev.port; + spin_lock_init(&port->lock); port->iotype = UPIO_MEM; port->mapbase = addr; port->uartclk = BASE_BAUD * 16; -- 2.20.1