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Yang Yingliang authored
I got a deadloop report while doing device(ds2482) add/remove test: [ 162.241881] w1_master_driver w1_bus_master1: Waiting for w1_bus_master1 to become free: refcnt=1. [ 163.272251] w1_master_driver w1_bus_master1: Waiting for w1_bus_master1 to become free: refcnt=1. [ 164.296157] w1_master_driver w1_bus_master1: Waiting for w1_bus_master1 to become free: refcnt=1. ... __w1_remove_master_device() can't return, because the dev->refcnt is not zero. w1_add_master_device() | w1_alloc_dev() | atomic_set(&dev->refcnt, 2) | kthread_run() | |__w1_remove_master_device() | kthread_stop() // KTHREAD_SHOULD_STOP is set, | // threadfn(w1_process) won't be | // called. | kthread() | | // refcnt will never be 0, it's deadloop. | while (atomic_read(&dev->refcnt)) {...} After calling w1_add_master_device(), w1_process() is not really invoked, before w1_process() starting, if kthread_stop() is called in __w1_remove_master_device(), w1_process() will never be called, the refcnt can not be decreased, then it causes deadloop in remove function because of non-zero refcnt. We need to make sure w1_process() is really started, so move the set refcnt into w1_process() to fix this problem. Fixes: 1da177e4 ("Linux-2.6.12-rc2") Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Link: https://lore.kernel.org/r/20221205080434.3149205-1-yangyingliang@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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