tools/sched_ext: Add helper to check task migration state

commit 5f52bbf2f6e0997394cf9c449d44e1c80ff4282c upstream.

Introduce a new helper for BPF schedulers to determine whether a task
can migrate or not (supporting both SMP and UP systems).

Fixes: e9fe182772dc ("sched_ext: selftests/dsp_local_on: Fix sporadic failures")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/sched_ext/include/scx/common.bpf.h b/tools/sched_ext/include/scx/common.bpf.h
index f7206374a73dd8dfc9aeabfa3fb128fec2d62498..75d6d61279d66440ecd91f5523639cd0c2ea7434 100644 (file)
--- a/tools/sched_ext/include/scx/common.bpf.h
+++ b/tools/sched_ext/include/scx/common.bpf.h
@@ -333,6 +333,17 @@ static __always_inline const struct cpumask *cast_mask(struct bpf_cpumask *mask)
        return (const struct cpumask *)mask;
 }
 
+/*
+ * Return true if task @p cannot migrate to a different CPU, false
+ * otherwise.
+ */
+static inline bool is_migration_disabled(const struct task_struct *p)
+{
+       if (bpf_core_field_exists(p->migration_disabled))
+               return p->migration_disabled;
+       return false;
+}
+
 /* rcu */
 void bpf_rcu_read_lock(void) __ksym;
 void bpf_rcu_read_unlock(void) __ksym;