[lttng-dev] Question about lock in synchronize_rcu implementation of URCU

Yuxin Ren ryx at gwmail.gwu.edu
Thu Apr 28 01:34:16 UTC 2016


I am learning the URCU code.

Why do we need rcu_gp_lock in synchronize_rcu?

In the comment, it says this lock ensures mutual exclusion between
threads calling synchronize_rcu().
But only the first thread added to waiter queue can proceed to detect
grace period.
How can multiple threads currently perform the grace thread?

Thanks a lot!

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