additional call_rcu() process to the site of the
emulated rcu-barrier().
- e. Although sleepable RCU (SRCU) is now modeled, there
- are some subtle differences between its semantics and
- those in the Linux kernel. For example, the kernel
- might interpret the following sequence as two partially
- overlapping SRCU read-side critical sections:
-
- 1 r1 = srcu_read_lock(&my_srcu);
- 2 do_something_1();
- 3 r2 = srcu_read_lock(&my_srcu);
- 4 do_something_2();
- 5 srcu_read_unlock(&my_srcu, r1);
- 6 do_something_3();
- 7 srcu_read_unlock(&my_srcu, r2);
-
- In contrast, LKMM will interpret this as a nested pair of
- SRCU read-side critical sections, with the outer critical
- section spanning lines 1-7 and the inner critical section
- spanning lines 3-5.
-
- This difference would be more of a concern had anyone
- identified a reasonable use case for partially overlapping
- SRCU read-side critical sections. For more information
- on the trickiness of such overlapping, please see:
- https://paulmck.livejournal.com/40593.html
-
- f. Reader-writer locking is not modeled. It can be
+ e. Reader-writer locking is not modeled. It can be
emulated in litmus tests using atomic read-modify-write
operations.