12.29

    no deadlock

    initial: a = 1, b = 1, c = 1

    thread 1 thread 2
    P(a) P(c)
    P(b) P(b)
    V(b) V(b)
    P(c) V(c)
    V(c) ——
    V(a) ——

    thread 2 doesn’t manipulate mutex a and initial a is 1, so P(a), V(a) don’t affect deadlock status.

    thread 1 thread 2
    P(b) P(c)
    V(b) P(b)
    P(c) V(b)
    V(c) V(c) 
    1.     +
    2.     |
    3.     |
    4.     +                             +----------+
    5. V(c)|                             |          |
    6.     |                             |          |
    7.     +                             |          |
    8.     |                             |          |
    9.     |                             |          |
    10.     +         +----------+        |          |
    11. V(b)|         |          |        |          |
    12.     |         |          |        |          |
    13.     +         |          |        |          |
    14.     |         |          |        |          |
    15.     |         |          |        |          |
    16.     +         +----------+        |          |
    17. P(b)|                             |          |
    18.     |                             |          |
    19.     +                             |          |
    20.     |                             |          |
    21.     |                             |          |
    22.     +                             +----------+
    23. P(c)|
    24.     |
    25.     +
    26.     |
    27.     |
    28.     +----+----+----+----+----+----+----+----+----+  thread 1
    29.           P(b)      V(b)      P(c)      V(c)