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From:   Paolo Valente <paolo.valente@linaro.org>
To:     Jens Axboe <axboe@kernel.dk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>,
        Angelo Ruocco <angeloruocco90@gmail.com>,
        Dennis Zhou <dennis@kernel.org>,
        Josef Bacik <josef@toxicpanda.com>,
        Liu Bo <bo.liu@linux.alibaba.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Johannes Weiner <hannes@cmpxchg.org>
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        ulf.hansson@linaro.org, linus.walleij@linaro.org,
        broonie@kernel.org, bfq-iosched@googlegroups.com,
        oleksandr@natalenko.name, cgroups@vger.kernel.org,
        linux-doc@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        Paolo Valente <paolo.valente@linaro.org>
Subject: [PATCH 05/12] cgroup: add owner name to cftypes
Date:   Mon, 12 Nov 2018 10:56:25 +0100
Message-Id: <20181112095632.69114-6-paolo.valente@linaro.org>
In-Reply-To: <20181112095632.69114-1-paolo.valente@linaro.org>
References: <20181112095632.69114-1-paolo.valente@linaro.org>
Sender: linux-kernel-owner@vger.kernel.org
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From: Angelo Ruocco <angeloruocco90@gmail.com>

The piece of information "who created a certain cftype" is not stored
anywhere, thus a cftype is not able to know who is its owner.

This commit addresses this problem by adding a new field in the cftype
structure that enables the name of its owner to be explicitly set.

Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
 include/linux/cgroup-defs.h |  2 ++
 include/linux/cgroup.h      | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index d659763c7221..6e31f478c6e1 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -36,6 +36,7 @@ struct seq_file;
 #define MAX_CGROUP_TYPE_NAMELEN 32
 #define MAX_CGROUP_ROOT_NAMELEN 64
 #define MAX_CFTYPE_NAME		64
+#define MAX_OWNER_NAME		64
 
 /* define the enumeration of all cgroup subsystems */
 #define SUBSYS(_x) _x ## _cgrp_id,
@@ -505,6 +506,7 @@ struct cftype {
 	 * end of cftype array.
 	 */
 	char name[MAX_CFTYPE_NAME];
+	char owner_name[MAX_OWNER_NAME];
 	unsigned long private;
 
 	/*
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 9968332cceed..bf17a9843f45 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -293,6 +293,19 @@ void css_task_iter_end(struct css_task_iter *it);
 			;						\
 		else
 
+/**
+ * list_for_each_cft - walk circular list of cftypes linked together
+ * @cft: cftype from where to start
+ * @n: cftype used as a temporary storage
+ *
+ * A cftype pointed by a file may be part of a circular list of cftypes, this
+ * macro walks the circular list starting from any given cftype. Unlike the
+ * "list_for_each_entry" macro, the first element is included in the iteration.
+ */
+#define list_for_each_cft(cft, n)					\
+	for (n = NULL; cft != n; n = (n == NULL) ? cft : n,		\
+	     cft = list_next_entry(cft, share_node))
+
 /*
  * Inline functions.
  */
-- 
2.16.1