From: Daniel Wagner <wagi-kQCPcA+X3s7YtjvyW6yDsg@public•gmane.org>
To: Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public•gmane.org>
Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public•gmane.org,
cgroups-u79uwXL29TY76Z2rM5mHXA@public•gmane.org,
Daniel Wagner
<daniel.wagner-98C5kh4wR6ohFhg+JK9F0w@public•gmane.org>,
Gao feng <gaofeng-BthXqXjhjHXQFUHtdCDX3A@public•gmane.org>,
Jamal Hadi Salim <jhs-jkUAjuhPggJWk0Htik3J/w@public•gmane.org>,
John Fastabend
<john.r.fastabend-ral2JQCrhuEAvxtiuMwx3w@public•gmane.org>,
Neil Horman <nhorman-2XuSBdqkA4R54TAoqtyWWQ@public•gmane.org>
Subject: Re: [PATCH v4 4/8] cgroup: Remove CGROUP_BUILTIN_SUBSYS_COUNT
Date: Thu, 13 Sep 2012 08:57:39 +0200 [thread overview]
Message-ID: <505183E3.3030409@monom.org> (raw)
In-Reply-To: <50517FFF.4030106-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
Hi Li,
On 13.09.2012 08:41, Li Zefan wrote:
>> @@ -1321,11 +1321,13 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
>> * take duplicate reference counts on a subsystem that's already used,
>> * but rebind_subsystems handles this case.
>> */
>> - for (i = CGROUP_BUILTIN_SUBSYS_COUNT; i < CGROUP_SUBSYS_COUNT; i++) {
>> + for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
>> unsigned long bit = 1UL << i;
>>
>> if (!(bit & opts->subsys_mask))
>> continue;
>> + if (!subsys[i]->module)
>> + continue;
>
> This check is not necessary. If it's builtin, try_module_get() will just return 1, and
> we're fine.
Yes, I didn't see the try_module_get. Although I think with leaving the
test away it would change the behavior, e.g.
if (!subsys[i]->module)
continue;
if (!try_module_get(subsys[i]->module)) {
module_pin_failed = true;
break;
}
module_pin_failed would be set then and we would jump into the error
code later.
This tests looks a bit ugly though I think leaving it away and relying
on try_module_get() is not correct.
>> @@ -1437,6 +1443,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp)
>> INIT_LIST_HEAD(&cgrp->event_list);
>> spin_lock_init(&cgrp->event_list_lock);
>> simple_xattrs_init(&cgrp->xattrs);
>> + memset(cgrp->subsys, 0, sizeof(cgrp->subsys));
>
> This seems an unrelated change, and is redundant. Am I missing something?
The reason why it is necessary to NULL all the entries in the array, is
that task_cls_classid() and task_netprioidx() check the return pointer
from task_subsys_state(). If it is NULL those function know that the
subsystem is not ready to be used. Should I move this change to the next
patch then?
cheers,
daniel
next prev parent reply other threads:[~2012-09-13 6:57 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-12 14:12 [PATCH v4 0/8] cgroup: Assign subsystem IDs during compile time Daniel Wagner
2012-09-12 14:12 ` [PATCH v4 2/8] cgroup: net_cls: Do not define task_cls_classid() when not selected Daniel Wagner
2012-09-13 6:35 ` Li Zefan
2012-09-12 14:12 ` [PATCH v4 3/8] cgroup: net_prio: Do not define task_netpioidx() " Daniel Wagner
[not found] ` <1347459128-32236-4-git-send-email-wagi-kQCPcA+X3s7YtjvyW6yDsg@public.gmane.org>
2012-09-13 6:36 ` Li Zefan
2012-09-12 14:12 ` [PATCH v4 4/8] cgroup: Remove CGROUP_BUILTIN_SUBSYS_COUNT Daniel Wagner
[not found] ` <1347459128-32236-5-git-send-email-wagi-kQCPcA+X3s7YtjvyW6yDsg@public.gmane.org>
2012-09-13 6:41 ` Li Zefan
[not found] ` <50517FFF.4030106-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2012-09-13 6:57 ` Daniel Wagner [this message]
[not found] ` <505183E3.3030409-kQCPcA+X3s7YtjvyW6yDsg@public.gmane.org>
2012-09-13 7:14 ` Li Zefan
[not found] ` <505187C8.9030001-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2012-09-13 7:38 ` Daniel Wagner
2012-09-12 14:12 ` [PATCH v4 6/8] cgroup: Do not depend on a given order when populating the subsys array Daniel Wagner
[not found] ` <1347459128-32236-7-git-send-email-wagi-kQCPcA+X3s7YtjvyW6yDsg@public.gmane.org>
2012-09-13 6:42 ` Li Zefan
2012-09-12 14:12 ` [PATCH v4 7/8] cgroup: Assign subsystem IDs during compile time Daniel Wagner
[not found] ` <1347459128-32236-8-git-send-email-wagi-kQCPcA+X3s7YtjvyW6yDsg@public.gmane.org>
2012-09-13 6:45 ` Li Zefan
2012-09-12 14:12 ` [PATCH v4 8/8] cgroup: Define CGROUP_SUBSYS_COUNT according the configuration Daniel Wagner
[not found] ` <1347459128-32236-9-git-send-email-wagi-kQCPcA+X3s7YtjvyW6yDsg@public.gmane.org>
2012-09-13 6:46 ` Li Zefan
[not found] ` <1347459128-32236-1-git-send-email-wagi-kQCPcA+X3s7YtjvyW6yDsg@public.gmane.org>
2012-09-12 14:12 ` [PATCH v4 1/8] cgroup: net_cls: Move sock_update_classid() declaration to cls_cgroup.h Daniel Wagner
[not found] ` <1347459128-32236-2-git-send-email-wagi-kQCPcA+X3s7YtjvyW6yDsg@public.gmane.org>
2012-09-13 6:34 ` Li Zefan
2012-09-12 14:12 ` [PATCH v4 5/8] cgroup: Wrap subsystem selection macro Daniel Wagner
[not found] ` <1347459128-32236-6-git-send-email-wagi-kQCPcA+X3s7YtjvyW6yDsg@public.gmane.org>
2012-09-13 6:41 ` Li Zefan
2012-09-12 18:56 ` [PATCH v4 0/8] cgroup: Assign subsystem IDs during compile time Tejun Heo
2012-09-13 14:01 ` Neil Horman
2012-09-13 18:13 ` Tejun Heo
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