On Wed, 11 Oct 2017 20:54:32 -0400 Rik van Riel <[email protected]> wrote:
> On Wed, 2017-10-11 at 15:37 -0700, Andrew Morton wrote: > > On Wed, 11 Oct 2017 18:19:38 -0400 Gargi Sharma <[email protected]> > > wrote: > > > > > This patch replaces the current bitmap implemetation for > > > Process ID allocation. Functions that are no longer required, > > > for example, free_pidmap(), alloc_pidmap(), etc. are removed. > > > The rest of the functions are modified to use the IDR API. > > > The change was made to make the PID allocation less complex by > > > replacing custom code with calls to generic API. > > > > I still don't understand the locking. spin_lock_irq(&pidmap_lock) in > > some places, rcu_read_lock() in others. > > > > If the locking is indeed now correct, can we please get it fully > > documented? A comment at the pid_namespace.idr definition site would > > suit. > > Would you like me to send a follow-up patch to document the > locking? Sure. > Documenting the locking on all the existing code, plus the > new code, seems a little out of scope of an Outreachy > internship... I'm not referring to all the existing code! Just this new pid_namespace.idr's locking. If it was protected by spin_lock_irq(&pidmap_lock) everywhere then an explanation wouldn't be needed. But we have this oddball site where pidmap_lock isn't taken but it uses rcu_read_lock() which is surprising to say the least. Readers could be forgiven for thinking that is a bug.
