On Mon, 30 Apr 2018 06:43:08 -0700 "Paul E. McKenney" <paul...@linux.vnet.ibm.com> wrote:
> On Sun, Apr 29, 2018 at 10:20:33PM -0700, Josh Triplett wrote: > > On Mon, Apr 30, 2018 at 02:31:30PM +1000, NeilBrown wrote: > > > list_for_each_entry_from_rcu() is an RCU version of > > > list_for_each_entry_from(). It walks a linked list under rcu > > > protection, from a given start point. > > > > > > It is similar to list_for_each_entry_continue_rcu() but starts *at* > > > the given position rather than *after* it. > > > > > > Naturally, the start point must be known to be in the list. > > > > I'd suggest giving an explicit advisory comment to clarify and suggest > > correct usage: > > > > "This would typically require either that you obtained the node from a > > previous walk of the list in the same RCU read-side critical section, or > > that you held some sort of non-RCU reference (such as a reference count) > > to keep the node alive *and* in the list." > > > > (Feel free to wordsmith the exact wording, but something like that seems > > like it would help people understand how to use this correctly, and make > > it less likely that they'd use it incorrectly.) > > What Josh said! Could you also contrast this with the existing > list_for_each_entry_continue_rcu() macro in the header comment as well > as in the commit log? > Should Documentation/RCU/whatisRCU.txt be updated? Specifically section: 7. FULL LIST OF RCU APIs -- Steve
