From: NeilBrown <neilb@suse.de>
To: Shaohua Li <shli@kernel.org>
Cc: linux-raid@vger.kernel.org, tj@kernel.org, dan.j.williams@gmail.com
Subject: Re: [patch v3 3/5] raid5: offload stripe handle to workqueue
Date: Wed, 28 Aug 2013 13:53:05 +1000 [thread overview]
Message-ID: <20130828135305.3f328d92@notabene.brown> (raw)
In-Reply-To: <20130827095452.202091257@kernel.org>
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On Tue, 27 Aug 2013 17:50:41 +0800 Shaohua Li <shli@kernel.org> wrote:
> -static struct stripe_head *__get_priority_stripe(struct r5conf *conf)
> +static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
> {
> - struct stripe_head *sh;
> + struct stripe_head *sh = NULL, *tmp;
> + struct list_head *handle_list = NULL;
> +
> + if (conf->worker_cnt_per_group == 0) {
> + handle_list = &conf->handle_list;
> + if (list_empty(handle_list))
> + handle_list = NULL;
> + } else if (group != ANY_GROUP) {
> + handle_list = &conf->worker_groups[group].handle_list;
> + if (list_empty(handle_list))
> + handle_list = NULL;
> + } else {
> + int i;
> + for (i = 0; i < conf->group_cnt; i++) {
> + handle_list = &conf->worker_groups[i].handle_list;
> + if (!list_empty(handle_list))
> + break;
> + }
> + if (i == conf->group_cnt)
> + handle_list = NULL;
> + }
Sorry, I meant to mention this last time...
The setting of handle_list to NULL seems unnecessary. It is sufficient to
test if it is empty.
The only interesting case is the last 'else' above. That is only reached if
worker_cnt_per_group != 0 so handle_list will get set to some list_head.
If all list_heads are empty, handle_list will be set to the last list_head
so a list_empty(handle_list) test is perfectly safe.
Also with the current code:
>
> pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
> __func__,
> - list_empty(&conf->handle_list) ? "empty" : "busy",
> + list_empty(handle_list) ? "empty" : "busy",
^^^^^^^^^^^^^^^^^^^^^^^
This will crash.
Could you fix that up please?
Thanks.
NeilBrown
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next prev parent reply other threads:[~2013-08-28 3:53 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-27 9:50 [patch v3 0/5] raid5: make stripe handling multi-threading Shaohua Li
2013-08-27 9:50 ` [patch v3 1/5] raid5: make release_stripe lockless Shaohua Li
2013-08-28 14:04 ` Tejun Heo
2013-08-28 14:29 ` Shaohua Li
2013-08-28 14:30 ` Tejun Heo
2013-08-27 9:50 ` [patch v3 2/5] raid5: fix stripe release order Shaohua Li
2013-08-28 3:41 ` NeilBrown
2013-08-28 6:29 ` Shaohua Li
2013-08-28 6:37 ` NeilBrown
2013-08-27 9:50 ` [patch v3 3/5] raid5: offload stripe handle to workqueue Shaohua Li
2013-08-28 3:53 ` NeilBrown [this message]
2013-08-28 6:30 ` Shaohua Li
2013-08-28 6:56 ` NeilBrown
2013-08-27 9:50 ` [patch v3 4/5] raid5: sysfs entry to control worker thread number Shaohua Li
2013-08-27 9:50 ` [patch v3 5/5] raid5: only wakeup necessary threads Shaohua Li
2013-08-28 4:13 ` NeilBrown
2013-08-28 6:31 ` Shaohua Li
2013-08-28 6:59 ` NeilBrown
2013-08-29 7:40 ` Shaohua Li
2013-09-02 0:45 ` NeilBrown
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