[lttng-dev] [RFC] re-document rculfstack and even rename it

Paul E. McKenney paulmck at linux.vnet.ibm.com
Wed Oct 10 10:59:59 EDT 2012

On Wed, Oct 10, 2012 at 03:52:08PM +0800, Lai Jiangshan wrote:
> rculfstack is not really require RCU-only.
> 1) cds_lfs_push_rcu() don't need any lock, don't need RCU nor other locks.
> 2) cds_lfs_pop_rcu() don't only one of the following synchronization(not only RCU):
> 	A) use rcu_read_lock() to protect cds_lfs_pop_rcu() and use synchronize_rcu()
>            or call_rcu() to free the popped node. (current comments said we need this
>            synchronization, and thus we named this struct with rcu prefix. But actually,
> 	   the followings are OK, and are more popular/friendly)
> 	B) use mutexs/locks to protect cds_lfs_pop_rcu(), we can free to free/modify the
> 	   popped node any time, we don't need any synchronization when free them.
> 	C) only ONE thread can call cds_lfs_pop_rcu(). (multi-providers-single customer)
> 	D) others, like read-write locks.
> I consider B) and C) are more popular. In linux kernel,
> kernel/task_work.c uses a hybird ways of B) and C).
> I suggest to rename it, Or document B) and C) at least.

Good timing -- stacks and queues are next on my list for documentation.  ;-)

							Thanx, Paul

More information about the lttng-dev mailing list