• Tejun Heo's avatar
    freezer: implement and use kthread_freezable_should_stop() · 8a32c441
    Tejun Heo authored
    Writeback and thinkpad_acpi have been using thaw_process() to prevent
    deadlock between the freezer and kthread_stop(); unfortunately, this
    is inherently racy - nothing prevents freezing from happening between
    thaw_process() and kthread_stop().
    This patch implements kthread_freezable_should_stop() which enters
    refrigerator if necessary but is guaranteed to return if
    kthread_stop() is invoked.  Both thaw_process() users are converted to
    use the new function.
    Note that this deadlock condition exists for many of freezable
    kthreads.  They need to be converted to use the new should_stop or
    freezable workqueue.
    Tested with synthetic test case.
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Acked-by: default avatarHenrique de Moraes Holschuh <ibm-acpi@hmh.eng.br>
    Cc: Jens Axboe <axboe@kernel.dk>
    Cc: Oleg Nesterov <oleg@redhat.com>
freezer.c 4.38 KB