scx_layered: Switch to scx_bpf_remote_curr()

The new scx_bpf_remote_curr() is safer to use, switch to it
from scx_bpf_cpu_rq() as we only care about it's ->curr anyway.

Signed-off-by: Christian Loehle <[email protected]>

Author: cloehle

scheds/rust/scx_layered/src/bpf/main.bpf.c

@@ -1249,7 +1249,6 @@ static bool try_preempt_cpu(s32 cand, struct task_struct *p, struct task_ctx *ta
 			    struct layer *layer, u64 flags)
 {
 	struct cpu_ctx *cpuc, *cand_cpuc, *sib_cpuc = NULL;
-	struct rq *rq;
 	struct task_struct *curr;
 	const struct cpumask *idle_cpumask;
 	bool cand_idle;
@@ -1276,19 +1275,20 @@ static bool try_preempt_cpu(s32 cand, struct task_struct *p, struct task_ctx *ta
 	if (scx_bpf_dsq_nr_queued(SCX_DSQ_LOCAL_ON | cand))
 		return false;
 
-	rq = scx_bpf_cpu_rq(cand);
-	if (!rq)
+	curr = scx_bpf_remote_curr(cand);
+	if (!curr)
 		return false;
-	curr = rq->curr;
 
 	if (ext_sched_class_addr && idle_sched_class_addr &&
 	    ((u64)curr->sched_class != ext_sched_class_addr) &&
 	    ((u64)curr->sched_class != idle_sched_class_addr)) {
+		bpf_task_release(curr);
 		if (!(cpuc = lookup_cpu_ctx(-1)))
 			return false;
 		gstat_inc(GSTAT_SKIP_PREEMPT, cpuc);
 		return false;
 	}
+	bpf_task_release(curr);
 
 	/*
 	 * Don't preempt if protection against is in effect. However, open