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    SubjectPatch: Fix serial module use count (2.4.16 _and_ 2.5)
    Hi,

    The existing serial.c contains a nice module use count bug which is easily
    triggerable. Without anything connected to ttyS0, do:

    stty -clocal -F /dev/ttyS0
    stty -aF /dev/ttyS0

    Hit ^c, lsmod shows use count of -1. Repeat to decrement further.

    Here's a patch that fixes this bogosity - please see the comment within
    the patch for the reason.

    Marcelo, please apply to both 2.4.
    Linus, please apply to 2.5 as a stop-gap until my new serial drivers are
    ready to be merged.

    Thanks.

    --- linux-orig/drivers/char/serial.c Tue Nov 13 12:37:12 2001
    +++ linux/drivers/char/serial.c Thu Nov 29 13:07:52 2001
    @@ -3133,6 +3133,10 @@
    * enables interrupts for a serial port, linking in its async structure into
    * the IRQ chain. It also performs the serial-specific
    * initialization for the tty structure.
    + *
    + * Note that on failure, we don't decrement the module use count - the tty
    + * later will call rs_close, which will decrement it for us as long as
    + * tty->driver_data is set non-NULL. --rmk
    */
    static int rs_open(struct tty_struct *tty, struct file * filp)
    {
    @@ -3153,10 +3157,8 @@
    }
    tty->driver_data = info;
    info->tty = tty;
    - if (serial_paranoia_check(info, tty->device, "rs_open")) {
    - MOD_DEC_USE_COUNT;
    + if (serial_paranoia_check(info, tty->device, "rs_open"))
    return -ENODEV;
    - }

    #ifdef SERIAL_DEBUG_OPEN
    printk("rs_open %s%d, count = %d\n", tty->driver.name, info->line,
    @@ -3171,10 +3173,8 @@
    */
    if (!tmp_buf) {
    page = get_zeroed_page(GFP_KERNEL);
    - if (!page) {
    - MOD_DEC_USE_COUNT;
    + if (!page)
    return -ENOMEM;
    - }
    if (tmp_buf)
    free_page(page);
    else
    @@ -3188,7 +3188,6 @@
    (info->flags & ASYNC_CLOSING)) {
    if (info->flags & ASYNC_CLOSING)
    interruptible_sleep_on(&info->close_wait);
    - MOD_DEC_USE_COUNT;
    #ifdef SERIAL_DO_RESTART
    return ((info->flags & ASYNC_HUP_NOTIFY) ?
    -EAGAIN : -ERESTARTSYS);
    @@ -3201,10 +3200,8 @@
    * Start up serial port
    */
    retval = startup(info);
    - if (retval) {
    - MOD_DEC_USE_COUNT;
    + if (retval)
    return retval;
    - }

    retval = block_til_ready(tty, filp, info);
    if (retval) {
    @@ -3212,7 +3209,6 @@
    printk("rs_open returning after block_til_ready with %d\n",
    retval);
    #endif
    - MOD_DEC_USE_COUNT;
    return retval;
    }


    --
    Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux
    http://www.arm.linux.org.uk/personal/aboutme.html

    -
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