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    Subject[PATCH 4.14 045/136] serial: amba-pl011: Make sure we initialize the port.lock spinlock
    Date
    From: John Stultz <john.stultz@linaro.org>

    [ Upstream commit 8508f4cba308f785b2fd4b8c38849c117b407297 ]

    Valentine reported seeing:

    [ 3.626638] INFO: trying to register non-static key.
    [ 3.626639] the code is fine but needs lockdep annotation.
    [ 3.626640] turning off the locking correctness validator.
    [ 3.626644] CPU: 7 PID: 51 Comm: kworker/7:1 Not tainted 5.7.0-rc2-00115-g8c2e9790f196 #116
    [ 3.626646] Hardware name: HiKey960 (DT)
    [ 3.626656] Workqueue: events deferred_probe_work_func
    [ 3.632476] sd 0:0:0:0: [sda] Optimal transfer size 8192 bytes not a multiple of physical block size (16384 bytes)
    [ 3.640220] Call trace:
    [ 3.640225] dump_backtrace+0x0/0x1b8
    [ 3.640227] show_stack+0x20/0x30
    [ 3.640230] dump_stack+0xec/0x158
    [ 3.640234] register_lock_class+0x598/0x5c0
    [ 3.640235] __lock_acquire+0x80/0x16c0
    [ 3.640236] lock_acquire+0xf4/0x4a0
    [ 3.640241] _raw_spin_lock_irqsave+0x70/0xa8
    [ 3.640245] uart_add_one_port+0x388/0x4b8
    [ 3.640248] pl011_register_port+0x70/0xf0
    [ 3.640250] pl011_probe+0x184/0x1b8
    [ 3.640254] amba_probe+0xdc/0x180
    [ 3.640256] really_probe+0xe0/0x338
    [ 3.640257] driver_probe_device+0x60/0xf8
    [ 3.640259] __device_attach_driver+0x8c/0xd0
    [ 3.640260] bus_for_each_drv+0x84/0xd8
    [ 3.640261] __device_attach+0xe4/0x140
    [ 3.640263] device_initial_probe+0x1c/0x28
    [ 3.640265] bus_probe_device+0xa4/0xb0
    [ 3.640266] deferred_probe_work_func+0x7c/0xb8
    [ 3.640269] process_one_work+0x2c0/0x768
    [ 3.640271] worker_thread+0x4c/0x498
    [ 3.640272] kthread+0x14c/0x158
    [ 3.640275] ret_from_fork+0x10/0x1c

    Which seems to be due to the fact that after allocating the uap
    structure, nothing initializes the spinlock.

    Its a little confusing, as uart_port_spin_lock_init() is one
    place where the lock is supposed to be initialized, but it has
    an exception for the case where the port is a console.

    This makes it seem like a deeper fix is needed to properly
    register the console, but I'm not sure what that entails, and
    Andy suggested that this approach is less invasive.

    Thus, this patch resolves the issue by initializing the spinlock
    in the driver, and resolves the resulting warning.

    Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
    Cc: Russell King <linux@armlinux.org.uk>
    Cc: Jiri Slaby <jslaby@suse.com>
    Cc: linux-serial@vger.kernel.org
    Reported-by: Valentin Schneider <valentin.schneider@arm.com>
    Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
    Signed-off-by: John Stultz <john.stultz@linaro.org>
    Reviewed-and-tested-by: Valentin Schneider <valentin.schneider@arm.com>
    Link: https://lore.kernel.org/r/20200428184050.6501-1-john.stultz@linaro.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/tty/serial/amba-pl011.c | 1 +
    1 file changed, 1 insertion(+)

    diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
    index 637f72fb6427f..e55b556337214 100644
    --- a/drivers/tty/serial/amba-pl011.c
    +++ b/drivers/tty/serial/amba-pl011.c
    @@ -2605,6 +2605,7 @@ static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,
    uap->port.fifosize = uap->fifosize;
    uap->port.flags = UPF_BOOT_AUTOCONF;
    uap->port.line = index;
    + spin_lock_init(&uap->port.lock);

    amba_ports[index] = uap;

    --
    2.25.1


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