Re: [PATCH 2/2] rcu/tasks: Further comment ordering around current task snapshot on TASK-TRACE

[Frederic Weisbecker]

Le Mon, May 20, 2024 at 04:25:33PM -0700, Paul E. McKenney a écrit :
> Good points!  How about the following?
> 
> 		// Note that cpu_curr_snapshot() picks up the target
> 		// CPU's current task while its runqueue is locked with
> 		// an smp_mb__after_spinlock().  This ensures that either
> 		// the grace-period kthread will see that task's read-side
> 		// critical section or the task will see the updater's pre-GP
> 		// accesses.  The trailng smp_mb() in cpu_curr_snapshot()

*trailing

> 		// does not currently play a role other than simplify
> 		// that function's ordering semantics.  If these simplified
> 		// ordering semantics continue to be redundant, that smp_mb()
> 		// might be removed.
> 
> Keeping in mind that the commit's log fully lays out the troublesome
> scenario.

Yep, looks very good!

Thanks!

> 
> 							Thanx, Paul
>