Re: [PATCH v2 04/12] rv: Prevent task migration while handling per-CPU events

[Nam Cao]

Gabriele Monaco <gmonaco@xxxxxxxxxx> writes:
> Tracepoint handlers are now fully preemptible.

Would be nice to mention the commit that did this:

a46023d5616e ("tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast")

> When a per-CPU monitor
> handles an event, it retrieves the monitor state using a per-CPU
> pointer. If the event itself doesn't disable preemption, the task can
> migrate to a different CPU and we risk updating the wrong monitor.
>
> Mitigate this by explicitly disabling task migration before acquiring
> the monitor pointer. This cannot guarantee the monitor runs on the
> correct CPU but reduces the race condition window and prevents warnings.
>
> Reviewed-by: Wen Yang <wen.yang@xxxxxxxxx>
> Signed-off-by: Gabriele Monaco <gmonaco@xxxxxxxxxx>

Reviewed-by: Nam Cao <namcao@xxxxxxxxxxxxx>