linux-kernel - [PATCH v2 14/14] cgroup: implement css

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140516160753.GD5379@htj.dyndns.org>
Date:	Fri, 16 May 2014 12:07:53 -0400
From:	Tejun Heo <tj@...nel.org>
To:	lizefan@...wei.com
Cc:	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
	hannes@...xchg.org
Subject: [PATCH v2 14/14] cgroup: implement css_tryget()

>From 141fdfadf18c10fed33624bbd414fcc0cb74d7ca Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@...nel.org>
Date: Fri, 16 May 2014 11:40:38 -0400

Implement css_tryget() which tries to grab a cgroup_subsys_state's
reference as long as it already hasn't reached zero.  Combined with
the recent css iterator changes to include offline && !released csses
during traversal, this can be used to access csses regardless of its
online state.

v2: Take the new flag CSS_NO_REF into account.

Signed-off-by: Tejun Heo <tj@...nel.org>
Acked-by: Li Zefan <lizefan@...wei.com>
Cc: Johannes Weiner <hannes@...xchg.org>
---
 include/linux/cgroup.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index b769999..4afe544 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -113,6 +113,24 @@ static inline void css_get(struct cgroup_subsys_state *css)
 }
 
 /**
+ * css_tryget - try to obtain a reference on the specified css
+ * @css: target css
+ *
+ * Obtain a reference on @css unless it already has reached zero and is
+ * being released.  This function doesn't care whether @css is on or
+ * offline.  The caller naturally needs to ensure that @css is accessible
+ * but doesn't have to be holding a reference on it - IOW, RCU protected
+ * access is good enough for this function.  Returns %true if a reference
+ * count was successfully obtained; %false otherwise.
+ */
+static inline bool css_tryget(struct cgroup_subsys_state *css)
+{
+	if (!(css->flags & CSS_NO_REF))
+		return percpu_ref_tryget(&css->refcnt);
+	return true;
+}
+
+/**
  * css_tryget_online - try to obtain a reference on the specified css if online
  * @css: target css
  *
-- 
1.9.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/