Re: [PATCH tip/core/rcu 0/13] Miscellaneous fixes for 4.4

[Josh Triplett]

On Tue, Oct 06, 2015 at 09:13:05AM -0700, Paul E. McKenney wrote:
> Hello!
> 
> This series contains miscellaneous fixes:
> 
> 1.	Export sched_setscheduler_nocheck() so that the new locktorture
> 	rtmutex_lock tests can be run as modules, courtesy of Davidlohr
> 	Bueso.
> 
> 2.	Use rcu_callback_t in call_rcu*() and friends to improve
> 	readability and to make cscope able to find them, courtesy of
> 	Boqun Feng.
> 
> 3.	Use call_rcu_func_t to replace explicit type equivalents when
> 	defining RCU callback functions, courtesy of Boqun Feng.
> 
> 4.	Don't unnecessarily disable preemption for Tiny and Tree
> 	RCU readers (only for preemptible RCU readers), courtesy
> 	of Boqun Feng.
> 
> 5.	Eliminate boot-time panic when a silly boot-time fanout is
> 	specified.
> 
> 6.	Add online/offline info to help debug stall-warning messages.
> 
> 7.	Move preemption disabling out of __srcu_read_lock() into
> 	srcu_read_lock().
> 
> 8.	Finish folding ->fqs_state into ->gp_state, courtesy of Petr Mladek.
> 
> 9.	Correct comment for values of ->gp_state field.
> 
> 10.	Add rcu_pointer_handoff() to allow explicit marking of handing
> 	off protection from RCU to some other means, such as locking
> 	or reference counting.
> 
> 11.	Make list_entry_rcu() use lockless_dereference(), courtesy
> 	of Patrick Marlier.  Despite the fact that this patch
> 	does nothing more than eliminate a single store and a
> 	single load of an unshared stack variable it nevertheless
> 	manages to provide a measurable performance increase:
> 	http://people.csail.mit.edu/amatveev/RLU_SOSP2015.pdf
> 
> 12.	Remove deprecated rcu_lockdep_assert().

(And a patch 13 not mentioned here.)

I responded to patches 4, 6, and 10 with feedback; for the rest (and for
those with the issues addressed):

Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
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