On Wed, 15 Jul 2020 18:35:00 -0400 Willem de Bruijn wrote: > On Wed, Jul 15, 2020 at 4:21 PM Jakub Kicinski <k...@kernel.org> wrote: > > > > On Tue, 7 Jul 2020 17:28:04 +0206 John Ogness wrote: > > > A busy-wait loop is used to implement waiting for bits to be copied > > > from the skb to the kernel buffer before retiring a block. This is > > > a problem on PREEMPT_RT because the copying task could be preempted > > > by the busy-waiting task and thus live lock in the busy-wait loop. > > > > > > Replace the busy-wait logic with an rwlock_t. This provides lockdep > > > coverage and makes the code RT ready. > > > > > > Signed-off-by: John Ogness <john.ogn...@linutronix.de> > > > > Is taking a lock and immediately releasing it better than a completion? > > Seems like the lock is guaranteed to dirty a cache line, which would > > otherwise be avoided here. > > > > Willem, would you be able to take a look as well? Is this path > > performance sensitive in real life? > > No objections from me. > > I guess this resolves the issue on preempt_rt, because the spinlocks act as > mutexes. It will still spin on write_lock otherwise, no huge difference from > existing logic.
Thanks! If no one else objects I'm putting this in net-next. Seems a little late for 5.8.
