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    SubjectRe: [PATCH 4/7] hvc_console: Fix race between hvc_close and hvc_remove
    Amit Shah wrote:
    > On (Fri) Mar 26 2010 [14:43:56], Sachin Sant wrote:
    >>> And this suggests that hvc_kick() is called before hvc_task is
    >>> initialised, ie, before hvc_init() is called.
    >>> Does this help?
    >> Hi Amit,
    >> I too ran into this issue as reported by Anton. Unfortunately in my
    >> case the following suggested patch does not help boot the powerpc
    >> box successfully. The boot still hangs with following messages
    > Was the hang you saw before applying this patch at the same place / for
    > the same reason?
    Yes the machine hangs at the same place with or without the patch.

    >> mount: can't find /root/proc in /etc/fstab or /etc/mtab
    >> /sbin/smart_agetty: can not determine 'console' speed
    > OK, this gets even murkier. I don't know why taking a few krefs modifies
    > hvc_console behaviour to such an extent.
    Looking at the commit e74d098c66543d0731de62eb747ccd5b636a6f4c,
    i see that for every tty_kref_get() there is a corresponding
    tty_kref_put() except maybe for the one in the following patch snippet

    spin_lock_irqsave(&hp->lock, flags);
    /* Check and then increment for fast path open. */
    if (hp->count++ > 0) {
    + tty_kref_get(tty);
    spin_unlock_irqrestore(&hp->lock, flags);
    return 0;

    I don't know this code very well but we might be missing a
    corresponding tty_kref_put() some place ?

    If i comment out the above tty_kref_get() call, the machine
    boots fine with or without the suggested patch.


    >> Just to confirm i too am facing same issue as reported by Anton,
    >> reverted commit e74d098c66543d0731de62eb747ccd5b636a6f4c and that allowed
    >> by box to boot successfully.
    > Which module uses hvc_console in your case?
    > Amit


    Sachin Sant
    IBM Linux Technology Center
    India Systems and Technology Labs
    Bangalore, India

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