On 11/10/23 12:32 PM, Alexei Starovoitov wrote:
On Fri, Nov 10, 2023 at 9:23 AM Yonghong Song <yonghong.song@xxxxxxxxx> wrote:+ if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { + if (!bpf_global_percpu_ma_set) { + mutex_lock(&bpf_verifier_lock); + if (!bpf_global_percpu_ma_set) { + err = bpf_mem_alloc_init(&bpf_global_percpu_ma, 0, true); + if (!err) + bpf_global_percpu_ma_set = true; + } + mutex_unlock(&bpf_verifier_lock);I feel we're taking unnecessary risk here by reusing the mutex. bpf_obj_new kfunc is a privileged operation and the verifier lock is not held in such scenario, so it won't deadlock,
That is true. deadlock situation won't happen.
but let's just add another mutex to protect percpu_ma init. Much easier to reason about.
Okay. will do.
