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authorGeert Uytterhoeven <geert+renesas@glider.be>2015-11-27 11:13:48 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-12-12 23:05:28 -0800
commite1dd3bef6d03c908b173259229b96074d57fccc8 (patch)
treeff5d5c92de7063fadd7358df5563578b324fe966 /drivers/tty/serial
parentd09959e7529451a1c302197fb1396ed5b835f6d3 (diff)
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: <none>/-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) [<c00173a0>] (unwind_backtrace) from [<c0013094>] (show_stack+0x10/0x14) [<c0013094>] (show_stack) from [<c01f2338>] (dump_stack+0x70/0x8c) [<c01f2338>] (dump_stack) from [<c00702d8>] (do_raw_spin_lock+0x20/0x190) [<c00702d8>] (do_raw_spin_lock) from [<c0267590>] (serial_console_write+0x4c/0x130) [<c0267590>] (serial_console_write) from [<c00734c4>] (call_console_drivers.constprop.13+0xc8/0xec) [<c00734c4>] (call_console_drivers.constprop.13) from [<c0074ef0>] (console_unlock+0x354/0x440) [<c0074ef0>] (console_unlock) from [<c0075bb4>] (register_console+0x2a0/0x394) [<c0075bb4>] (register_console) from [<c06cb750>] (of_setup_earlycon+0x90/0xa4) [<c06cb750>] (of_setup_earlycon) from [<c06cfb60>] (setup_of_earlycon+0x118/0x13c) [<c06cfb60>] (setup_of_earlycon) from [<c06b34ac>] (do_early_param+0x64/0xb4) [<c06b34ac>] (do_early_param) from [<c00472c0>] (parse_args+0x254/0x350) [<c00472c0>] (parse_args) from [<c06b3860>] (parse_early_options+0x2c/0x3c) [<c06b3860>] (parse_early_options) from [<c06b389c>] (parse_early_param+0x2c/0x40) [<c06b389c>] (parse_early_param) from [<c06b5b08>] (setup_arch+0x520/0xaf0) [<c06b5b08>] (setup_arch) from [<c06b3948>] (start_kernel+0x94/0x370) [<c06b3948>] (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 <geert+renesas@glider.be> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Reported-by: Bjorn Andersson <bjorn.andersson@sonymobile.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial')
-rw-r--r--drivers/tty/serial/earlycon.c2
1 files changed, 2 insertions, 0 deletions
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;