On 4/20/18, David Miller <[email protected]> wrote:
> From: Li RongQing <[email protected]>
> Date: Thu, 19 Apr 2018 12:59:21 +0800
>
>> The input of css_cls_state() is impossible to NULL except
>> cgrp_css_online, so simplify it
>>
>> Signed-off-by: Li RongQing <[email protected]>
>
> I don't view this as an improvement. Just let the helper always check
> NULL and that way there are less situations to audit.
>
css_cls_state maybe return NULL, but nearly no places check the return
value with NULL, this seems unreadable.
net/core/netclassid_cgroup.c:27: return
css_cls_state(task_css_check(p, net_cls_cgrp_id,
net/core/netclassid_cgroup.c:46: struct cgroup_cls_state *cs =
css_cls_state(css);
net/core/netclassid_cgroup.c:47: struct cgroup_cls_state
*parent = css_cls_state(css->parent);
net/core/netclassid_cgroup.c:57: kfree(css_cls_state(css));
net/core/netclassid_cgroup.c:82: (void
*)(unsigned long)css_cls_state(css)->classid);
net/core/netclassid_cgroup.c:89: return css_cls_state(css)->classid;
net/core/netclassid_cgroup.c:95: struct cgroup_cls_state *cs =
css_cls_state(css);
> And it's not like this is a critical fast path either.
>
I see css_cls_state will be called when send packet if
CONFIG_NET_CLS_ACT and CONFIG_NET_EGRESS enabled, the calling stack is
like below:
css_cls_state
task_cls_state
task_get_classid
cls_cgroup_classify
tcf_classify
sch_handle_egress
__dev_queue_xmit
CONFIG_NET_CLS_ACT
CONFIG_NET_EGRESS
-RongQing
> I'm not applying this, sorry.
>
