When is to preempt safe?

[Parmenides]

2011/10/8 Chetan Nanda <chetannanda at gmail.com>:
>
> New task pick by scheduler may try to get the same lock resulting in
> deadlock

It seems that this kind of deadlock may be removed eventually. Suppose
that we have a task A, which is holding a spinlock. If A is preempted
by task B which try to obtain the same spinlock. Although B has to
busy wait, it will end up with be preempted owing to using up its
timeslice. Therefore, A has chance to be selected by shechedler and
release the spinlock. Then, B will go on when it is selected by the
secheduler next time.