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    SubjectRe: [PATCH] kthread: saa7134-tvaudio.c
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    ebiederm@xmission.com (Eric W. Biederman) writes:

    > Andrew Morton <akpm@osdl.org> writes:
    >
    >> So in general, yes, the driver should be converted to the kthread API -
    >> this is a requirement for virtualisation, but I forget why, and that's the
    >> "standard" way of doing it.
    >
    > With the kthread api new kernel threads are started as children of keventd
    > in well defined circumstances. If you don't do this kernel threads
    > can wind up sharing weird parts of a parent process's resources and
    > locking resources in the kernel long past the time when they are
    > actually used by anything a user space process can kill.
    >
    > We have actually witnessed this problem with the kernels filesystem mount
    > namespace. Mostly daemonize in the kernel unshares everything that
    > could be a problem but the problem is sufficiently subtle it makes
    > more sense to the change kernel threads. So these weird and subtle
    > dependencies go away.
    >
    > So in essence the container work needs the new kthread api for the
    > same reasons everyone else does it is just more pronounced in that
    > case.

    That plus the obvious bit. For the pid namespace we have to declare
    war on people storing a pid_t values. Either converting them to
    struct pid * or removing them entirely. Doing the kernel_thread to
    kthread conversion removes them entirely.

    Eric
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