sched_ext: Add __COMPAT helpers for features added during v6.12 devel cycle

cgroup support and scx_bpf_dispatch[_vtime]_from_dsq() are newly added since
8bb30798fd6e ("sched_ext: Fixes incorrect type in bpf_scx_init()") which is
the current earliest commit targeted by BPF schedulers. Add compat helpers
for them and apply them in the example schedulers.

These will be dropped after a few kernel releases. The exact backward
compatibility window hasn't been decided yet.

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/tools/sched_ext/include/scx/compat.bpf.h b/tools/sched_ext/include/scx/compat.bpf.h
index 3d2fe1208900554066a8fca618e8831710f2486d..e5afe9efd3f318ec6c6ea6769434ffbdfb272dec 100644 (file)
--- a/tools/sched_ext/include/scx/compat.bpf.h
+++ b/tools/sched_ext/include/scx/compat.bpf.h
@@ -15,6 +15,25 @@
        __ret;                                                                  \
 })
 
+/* v6.12: 819513666966 ("sched_ext: Add cgroup support") */
+#define __COMPAT_scx_bpf_task_cgroup(p)                                                \
+       (bpf_ksym_exists(scx_bpf_task_cgroup) ?                                 \
+        scx_bpf_task_cgroup((p)) : NULL)
+
+/* v6.12: 4c30f5ce4f7a ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()") */
+#define __COMPAT_scx_bpf_dispatch_from_dsq_set_slice(it, slice)                        \
+       (bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_slice) ?                 \
+        scx_bpf_dispatch_from_dsq_set_slice((it), (slice)) : (void)0)
+#define __COMPAT_scx_bpf_dispatch_from_dsq_set_vtime(it, vtime)                        \
+       (bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_vtime) ?                 \
+        scx_bpf_dispatch_from_dsq_set_vtime((it), (vtime)) : (void)0)
+#define __COMPAT_scx_bpf_dispatch_from_dsq(it, p, dsq_id, enq_flags)           \
+       (bpf_ksym_exists(scx_bpf_dispatch_from_dsq) ?                           \
+        scx_bpf_dispatch_from_dsq((it), (p), (dsq_id), (enq_flags)) : false)
+#define __COMPAT_scx_bpf_dispatch_vtime_from_dsq(it, p, dsq_id, enq_flags)     \
+       (bpf_ksym_exists(scx_bpf_dispatch_vtime_from_dsq) ?                     \
+        scx_bpf_dispatch_vtime_from_dsq((it), (p), (dsq_id), (enq_flags)) : false)
+
 /*
  * Define sched_ext_ops. This may be expanded to define multiple variants for
  * backward compatibility. See compat.h::SCX_OPS_LOAD/ATTACH().

diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c
index 3ab2b60781a0d9d366b194e50624bce869cacbb4..936415b98ae7be5d48e80a78a5b99dab3db8c8bf 100644 (file)
--- a/tools/sched_ext/scx_flatcg.bpf.c
+++ b/tools/sched_ext/scx_flatcg.bpf.c
@@ -383,7 +383,7 @@ void BPF_STRUCT_OPS(fcg_enqueue, struct task_struct *p, u64 enq_flags)
                return;
        }
 
-       cgrp = scx_bpf_task_cgroup(p);
+       cgrp = __COMPAT_scx_bpf_task_cgroup(p);
        cgc = find_cgrp_ctx(cgrp);
        if (!cgc)
                goto out_release;
@@ -509,7 +509,7 @@ void BPF_STRUCT_OPS(fcg_runnable, struct task_struct *p, u64 enq_flags)
 {
        struct cgroup *cgrp;
 
-       cgrp = scx_bpf_task_cgroup(p);
+       cgrp = __COMPAT_scx_bpf_task_cgroup(p);
        update_active_weight_sums(cgrp, true);
        bpf_cgroup_release(cgrp);
 }
@@ -522,7 +522,7 @@ void BPF_STRUCT_OPS(fcg_running, struct task_struct *p)
        if (fifo_sched)
                return;
 
-       cgrp = scx_bpf_task_cgroup(p);
+       cgrp = __COMPAT_scx_bpf_task_cgroup(p);
        cgc = find_cgrp_ctx(cgrp);
        if (cgc) {
                /*
@@ -565,7 +565,7 @@ void BPF_STRUCT_OPS(fcg_stopping, struct task_struct *p, bool runnable)
        if (!taskc->bypassed_at)
                return;
 
-       cgrp = scx_bpf_task_cgroup(p);
+       cgrp = __COMPAT_scx_bpf_task_cgroup(p);
        cgc = find_cgrp_ctx(cgrp);
        if (cgc) {
                __sync_fetch_and_add(&cgc->cvtime_delta,
@@ -579,7 +579,7 @@ void BPF_STRUCT_OPS(fcg_quiescent, struct task_struct *p, u64 deq_flags)
 {
        struct cgroup *cgrp;
 
-       cgrp = scx_bpf_task_cgroup(p);
+       cgrp = __COMPAT_scx_bpf_task_cgroup(p);
        update_active_weight_sums(cgrp, false);
        bpf_cgroup_release(cgrp);
 }

diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c
index 83c8f54c1e31d896f5c0e793da559db9114ef0e2..67e2a7968cc913efd673bb48b95c13ad502168bc 100644 (file)
--- a/tools/sched_ext/scx_qmap.bpf.c
+++ b/tools/sched_ext/scx_qmap.bpf.c
@@ -318,11 +318,11 @@ static bool dispatch_highpri(bool from_timer)
 
                if (tctx->highpri) {
                        /* exercise the set_*() and vtime interface too */
-                       scx_bpf_dispatch_from_dsq_set_slice(
+                       __COMPAT_scx_bpf_dispatch_from_dsq_set_slice(
                                BPF_FOR_EACH_ITER, slice_ns * 2);
-                       scx_bpf_dispatch_from_dsq_set_vtime(
+                       __COMPAT_scx_bpf_dispatch_from_dsq_set_vtime(
                                BPF_FOR_EACH_ITER, highpri_seq++);
-                       scx_bpf_dispatch_vtime_from_dsq(
+                       __COMPAT_scx_bpf_dispatch_vtime_from_dsq(
                                BPF_FOR_EACH_ITER, p, HIGHPRI_DSQ, 0);
                }
        }
@@ -340,9 +340,9 @@ static bool dispatch_highpri(bool from_timer)
                else
                        cpu = scx_bpf_pick_any_cpu(p->cpus_ptr, 0);
 
-               if (scx_bpf_dispatch_from_dsq(BPF_FOR_EACH_ITER, p,
-                                             SCX_DSQ_LOCAL_ON | cpu,
-                                             SCX_ENQ_PREEMPT)) {
+               if (__COMPAT_scx_bpf_dispatch_from_dsq(BPF_FOR_EACH_ITER, p,
+                                                      SCX_DSQ_LOCAL_ON | cpu,
+                                                      SCX_ENQ_PREEMPT)) {
                        if (cpu == this_cpu) {
                                dispatched = true;
                                __sync_fetch_and_add(&nr_expedited_local, 1);