From a08b4dcad9fae495bcd88b91fb3410abf77d268e Mon Sep 17 00:00:00 2001 From: Andrea Righi Date: Thu, 4 Sep 2025 07:31:00 +0200 Subject: [PATCH] tools/sched_ext: Add compat helper for scx_bpf_cpu_curr() Introduce a compatibility helper that allows BPF schedulers to use scx_bpf_cpu_curr() on older kernels. Fixes: 20b158094a1ad ("sched_ext: Introduce scx_bpf_cpu_curr()") Cc: Christian Loehle Signed-off-by: Andrea Righi Signed-off-by: Tejun Heo --- tools/sched_ext/include/scx/common.bpf.h | 2 +- tools/sched_ext/include/scx/compat.bpf.h | 17 +++++++++++++++++ 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/tools/sched_ext/include/scx/common.bpf.h b/tools/sched_ext/include/scx/common.bpf.h index 342c7c48df5ab..06e2551033cb1 100644 --- a/tools/sched_ext/include/scx/common.bpf.h +++ b/tools/sched_ext/include/scx/common.bpf.h @@ -104,7 +104,7 @@ bool scx_bpf_task_running(const struct task_struct *p) __ksym; s32 scx_bpf_task_cpu(const struct task_struct *p) __ksym; struct rq *scx_bpf_cpu_rq(s32 cpu) __ksym; struct rq *scx_bpf_locked_rq(void) __ksym; -struct task_struct *scx_bpf_cpu_curr(s32 cpu) __ksym; +struct task_struct *scx_bpf_cpu_curr(s32 cpu) __ksym __weak; struct cgroup *scx_bpf_task_cgroup(struct task_struct *p) __ksym __weak; u64 scx_bpf_now(void) __ksym __weak; void scx_bpf_events(struct scx_event_stats *events, size_t events__sz) __ksym __weak; diff --git a/tools/sched_ext/include/scx/compat.bpf.h b/tools/sched_ext/include/scx/compat.bpf.h index 36e0cd2fd4eda..dd9144624dc99 100644 --- a/tools/sched_ext/include/scx/compat.bpf.h +++ b/tools/sched_ext/include/scx/compat.bpf.h @@ -230,6 +230,23 @@ static inline bool __COMPAT_is_enq_cpu_selected(u64 enq_flags) scx_bpf_pick_any_cpu_node(cpus_allowed, node, flags) : \ scx_bpf_pick_any_cpu(cpus_allowed, flags)) +/* + * v6.18: Add a helper to retrieve the current task running on a CPU. + * + * Keep this helper available until v6.20 for compatibility. + */ +static inline struct task_struct *__COMPAT_scx_bpf_cpu_curr(int cpu) +{ + struct rq *rq; + + if (bpf_ksym_exists(scx_bpf_cpu_curr)) + return scx_bpf_cpu_curr(cpu); + + rq = scx_bpf_cpu_rq(cpu); + + return rq ? rq->curr : NULL; +} + /* * Define sched_ext_ops. This may be expanded to define multiple variants for * backward compatibility. See compat.h::SCX_OPS_LOAD/ATTACH(). -- 2.47.3