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But in fact, most of these operations don't really need the > group->mutex. Are you sure? sysfs requires unique names, and this mutex is providing a guarentee that will happen. While it shouldn't be possible to race remove and attach, it is easier to reason about if we don't have to make this assumption. > Subsequent changes will introduce sleepable operations to this function: > + synchronize_rcu() to defer the gdev->dev put past a grace period. I'm not keen on that at all. Jason