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| author | Andrea Righi <arighi@nvidia.com> | 2025-05-15 22:11:43 +0300 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2025-05-20 23:24:05 +0300 |
| commit | 686d1337237161833684d8554c6e3ea2d692bd41 (patch) | |
| tree | a6049e6c59698850afb8b8a7df429ac516c9daee /kernel | |
| parent | 617a77018f683905ed4e8cd693df51243908353f (diff) | |
| download | linux-686d1337237161833684d8554c6e3ea2d692bd41.tar.xz | |
sched_ext: idle: Validate locking correctness in scx_bpf_select_cpu_and()
Validate locking correctness when accessing p->nr_cpus_allowed and
p->cpus_ptr inside scx_bpf_select_cpu_and(): if the rq lock is held,
access is safe; otherwise, require that p->pi_lock is held.
This allows to catch potential unsafe calls to scx_bpf_select_cpu_and().
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/ext_idle.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/sched/ext_idle.c b/kernel/sched/ext_idle.c index f0ebf8b5b908..716863f1f8ce 100644 --- a/kernel/sched/ext_idle.c +++ b/kernel/sched/ext_idle.c @@ -935,6 +935,7 @@ prev_cpu: __bpf_kfunc s32 scx_bpf_select_cpu_and(struct task_struct *p, s32 prev_cpu, u64 wake_flags, const struct cpumask *cpus_allowed, u64 flags) { + struct rq *rq; s32 cpu; if (!kf_cpu_valid(prev_cpu, NULL)) @@ -946,6 +947,15 @@ __bpf_kfunc s32 scx_bpf_select_cpu_and(struct task_struct *p, s32 prev_cpu, u64 if (!scx_kf_allowed(SCX_KF_SELECT_CPU | SCX_KF_ENQUEUE)) return -EPERM; + /* + * Validate locking correctness to access p->cpus_ptr and + * p->nr_cpus_allowed: if we're holding an rq lock, we're safe; + * otherwise, assert that p->pi_lock is held. + */ + rq = scx_locked_rq(); + if (!rq) + lockdep_assert_held(&p->pi_lock); + #ifdef CONFIG_SMP /* * This may also be called from ops.enqueue(), so we need to handle |