On Wed, 27 Jan 2021 13:13:22 -0500 (EST)
Mathieu Desnoyers <[email protected]> wrote:
> > Thanks for bringing that up.
>
> Requiring an RCU synchronize on element removal is quite intrusive, and can
> be problematic if tracepoint removal is called from e.g. preempt-off context.
But how often do you remove more than one callback from the same
tracepoint? Or should I say, from a lot of tracepoints?
This will only synchronize for the following case:
Add three callbacks to a single tracepoint.
Remove the first one.
<rcu callback to update the counters>
Remove the second one
<triggers a synchronization if the counters have not been finished
updating>
Remove the third one.
<no synchronization needed, because it's being freed>
And we may be able to make this work in batch too.
More to come, but I really like this approach over the others because it
does not increase the size of the kernel for a failure that should never
happen in practice.
-- Steve
