diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/syscall.c | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 274039e36465..700938782bed 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3261,6 +3261,18 @@ static void bpf_link_defer_dealloc_rcu_gp(struct rcu_head *rcu) bpf_link_dealloc(link); } +static bool bpf_link_is_tracepoint(struct bpf_link *link) +{ + /* + * Only these combinations support a tracepoint bpf_link. + * BPF_LINK_TYPE_TRACING raw_tp progs are hardcoded to use + * bpf_raw_tp_link_lops and thus dealloc_deferred(), see + * bpf_raw_tp_link_attach(). + */ + return link->type == BPF_LINK_TYPE_RAW_TRACEPOINT || + (link->type == BPF_LINK_TYPE_TRACING && link->attach_type == BPF_TRACE_RAW_TP); +} + static void bpf_link_defer_dealloc_mult_rcu_gp(struct rcu_head *rcu) { if (rcu_trace_implies_rcu_gp()) @@ -3279,16 +3291,25 @@ static void bpf_link_free(struct bpf_link *link) if (link->prog) ops->release(link); if (ops->dealloc_deferred) { - /* Schedule BPF link deallocation, which will only then + /* + * Schedule BPF link deallocation, which will only then * trigger putting BPF program refcount. * If underlying BPF program is sleepable or BPF link's target * attach hookpoint is sleepable or otherwise requires RCU GPs * to ensure link and its underlying BPF program is not * reachable anymore, we need to first wait for RCU tasks - * trace sync, and then go through "classic" RCU grace period + * trace sync, and then go through "classic" RCU grace period. + * + * For tracepoint BPF links, we need to go through SRCU grace + * period wait instead when non-faultable tracepoint is used. We + * don't need to chain SRCU grace period waits, however, for the + * faultable case, since it exclusively uses RCU Tasks Trace. */ if (link->sleepable || (link->prog && link->prog->sleepable)) call_rcu_tasks_trace(&link->rcu, bpf_link_defer_dealloc_mult_rcu_gp); + /* We need to do a SRCU grace period wait for non-faultable tracepoint BPF links. */ + else if (bpf_link_is_tracepoint(link)) + call_tracepoint_unregister_atomic(&link->rcu, bpf_link_defer_dealloc_rcu_gp); else call_rcu(&link->rcu, bpf_link_defer_dealloc_rcu_gp); } else if (ops->dealloc) { |