Please give an example

Question

Is deadlock possible in Test Set Lock?

Answer 1

Yes there is spin lock which is kind of deadlock .. it occur due to priority inversion problem .

1. TSL lock R( load lock R ,store #1 ,lock )

2. cmp R ,#0

3 critical section

4 exit section (release lock)

suppose there is 2 process p1 and p2 intial R =0 and for now line 1 is exected by process p1 and it enter into critical section  .now p2 comes which is high priority than p1 so p1 is preempted and go in ready queue and p2 execute the line 1 and 2 but lock R is not 0 . so it will be in busy waiting until it get critical section so we cant preempt it and p1 is in queue so it could not release the lock . and fall in deadlock .

Comments

Spin lock is busy waiting and is not same as deadlock. Also preemption can't happen like this in critical section- the scheduler should take care of this. Did you see this problem somewhere?

Ref: https://en.wikipedia.org/wiki/Critical_section

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No sir , i didnt see this problem .. spin lock is busy waiting but it could be in deadlock also . as  i  thought high priority process will be in running state and other one will be in queue  .  but if critical section does not allow preemption then there will starvation not deadlock .

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what about this article this is not deadlock.?https://gateoverflow.in/1319/gate2009-33

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in given linked question ,no deadlock .. what do want to ask ?