Re: [Patch net-next v2] net_sched: use idr to allocate bpf filter handles
From: Daniel Borkmann <daniel@iogearbox.net>
Date: 2017-09-25 21:16:55
On 09/25/2017 07:13 PM, Cong Wang wrote:
Instead of calling cls_bpf_get() in a loop to find a unused handle, just switch to idr API to allocate new handles. Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Chris Mi <redacted> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Cong Wang <redacted>
[...]
quoted hunk ↗ jump to hunk
@@ -476,21 +462,30 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, } } - if (handle == 0) - prog->handle = cls_bpf_grab_new_handle(tp, head); - else + if (handle == 0) { + ret = idr_alloc_ext(&head->handle_idr, prog, &idr_index, + 1, 0x7FFFFFFF, GFP_KERNEL); + if (ret) + goto errout; + prog->handle = idr_index; + } else { + if (!oldprog) { + ret = idr_alloc_ext(&head->handle_idr, prog, &idr_index, + handle, handle + 1, GFP_KERNEL); + if (ret) + goto errout; + } prog->handle = handle; - if (prog->handle == 0) { - ret = -EINVAL; - goto errout; } ret = cls_bpf_set_parms(net, tp, prog, base, tb, tca[TCA_RATE], ovr); if (ret < 0) - goto errout; + goto errout_idr; ret = cls_bpf_offload(tp, prog, oldprog); if (ret) { + if (!oldprog) + idr_remove_ext(&head->handle_idr, prog->handle);
Shouldn't we also call idr_remove_ext() when there was an
oldprog, but we didn't care about reusing the same handle,
so it was handle == 0 initially?
There's this condition in the code before above idr allocations,
I think also in other classifiers:
if (oldprog) {
if (handle && oldprog->handle != handle) {
ret = -EINVAL;
goto errout;
}
}
quoted hunk ↗ jump to hunk
__cls_bpf_delete_prog(prog); return ret; }@@ -499,6 +494,7 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, prog->gen_flags |= TCA_CLS_FLAGS_NOT_IN_HW; if (oldprog) { + idr_replace_ext(&head->handle_idr, prog, handle);
And here, we should probably use prog->handle for the above mentioned case as well, no? Would be great if all this (and e.g. the fact that we use idr itself) could optionally be hidden behind some handle generator api given we could reuse that api also for cls_basic and cls_u32. Could also be followed-up perhaps.
quoted hunk ↗ jump to hunk
list_replace_rcu(&oldprog->link, &prog->link); tcf_unbind_filter(tp, &oldprog->res); call_rcu(&oldprog->rcu, cls_bpf_delete_prog_rcu);@@ -509,6 +505,9 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, *arg = prog; return 0; +errout_idr: + if (!oldprog) + idr_remove_ext(&head->handle_idr, prog->handle);
(Likewise as the failing cls_bpf_offload().)
errout: tcf_exts_destroy(&prog->exts); kfree(prog);