lkml.org 
[lkml]   [2020]   [Jun]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.4 201/261] serial: 8250: Avoid error message on reprobe
    Date
    From: Lukas Wunner <lukas@wunner.de>

    commit e0a851fe6b9b619527bd928aa93caaddd003f70c upstream.

    If the call to uart_add_one_port() in serial8250_register_8250_port()
    fails, a half-initialized entry in the serial_8250ports[] array is left
    behind.

    A subsequent reprobe of the same serial port causes that entry to be
    reused. Because uart->port.dev is set, uart_remove_one_port() is called
    for the half-initialized entry and bails out with an error message:

    bcm2835-aux-uart 3f215040.serial: Removing wrong port: (null) != (ptrval)

    The same happens on failure of mctrl_gpio_init() since commit
    4a96895f74c9 ("tty/serial/8250: use mctrl_gpio helpers").

    Fix by zeroing the uart->port.dev pointer in the probe error path.

    The bug was introduced in v2.6.10 by historical commit befff6f5bf5f
    ("[SERIAL] Add new port registration/unregistration functions."):
    https://git.kernel.org/tglx/history/c/befff6f5bf5f

    The commit added an unconditional call to uart_remove_one_port() in
    serial8250_register_port(). In v3.7, commit 835d844d1a28 ("8250_pnp:
    do pnp probe before legacy probe") made that call conditional on
    uart->port.dev which allows me to fix the issue by zeroing that pointer
    in the error path. Thus, the present commit will fix the problem as far
    back as v3.7 whereas still older versions need to also cherry-pick
    835d844d1a28.

    Fixes: 835d844d1a28 ("8250_pnp: do pnp probe before legacy probe")
    Signed-off-by: Lukas Wunner <lukas@wunner.de>
    Cc: stable@vger.kernel.org # v2.6.10
    Cc: stable@vger.kernel.org # v2.6.10: 835d844d1a28: 8250_pnp: do pnp probe before legacy
    Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
    Link: https://lore.kernel.org/r/b4a072013ee1a1d13ee06b4325afb19bda57ca1b.1589285873.git.lukas@wunner.de
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/tty/serial/8250/8250_core.c | 14 ++++++++++----
    1 file changed, 10 insertions(+), 4 deletions(-)

    --- a/drivers/tty/serial/8250/8250_core.c
    +++ b/drivers/tty/serial/8250/8250_core.c
    @@ -1026,7 +1026,7 @@ int serial8250_register_8250_port(struct
    gpios = mctrl_gpio_init(&uart->port, 0);
    if (IS_ERR(gpios)) {
    ret = PTR_ERR(gpios);
    - goto out_unlock;
    + goto err;
    } else {
    uart->gpios = gpios;
    }
    @@ -1075,8 +1075,10 @@ int serial8250_register_8250_port(struct
    serial8250_apply_quirks(uart);
    ret = uart_add_one_port(&serial8250_reg,
    &uart->port);
    - if (ret == 0)
    - ret = uart->port.line;
    + if (ret)
    + goto err;
    +
    + ret = uart->port.line;
    } else {
    dev_info(uart->port.dev,
    "skipping CIR port at 0x%lx / 0x%llx, IRQ %d\n",
    @@ -1098,10 +1100,14 @@ int serial8250_register_8250_port(struct
    }
    }

    -out_unlock:
    mutex_unlock(&serial_mutex);

    return ret;
    +
    +err:
    + uart->port.dev = NULL;
    + mutex_unlock(&serial_mutex);
    + return ret;
    }
    EXPORT_SYMBOL(serial8250_register_8250_port);


    \
     
     \ /
      Last update: 2020-06-19 17:25    [W:4.359 / U:0.236 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site