latencytop: use the last element of latency_record of system

In account_global_scheduler_latency(), when we don't find the matching
latency_record we try to select one which is unused in
latency_record[MAXLR], but the condition will skip the last one.

if (i >= MAXLR-1)

Fix that.

Link: https://lkml.kernel.org/r/20220903135233.5225-1-wuchi.zero@gmail.comSigned-off-by: wuchi <wuchi.zero@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foudation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kernel/latencytop.c

@@ -112,7 +112,7 @@ static void __sched
 account_global_scheduler_latency(struct task_struct *tsk,
 				 struct latency_record *lat)
 {
-	int firstnonnull = MAXLR + 1;
+	int firstnonnull = MAXLR;
 	int i;
 
 	/* skip kernel threads for now */
@@ -150,7 +150,7 @@ account_global_scheduler_latency(struct task_struct *tsk,
 	}
 
 	i = firstnonnull;
-	if (i >= MAXLR - 1)
+	if (i >= MAXLR)
 		return;
 
 	/* Allocted a new one: */