From: "tip-bot2 for Paul E. McKenney" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: "Paul E. McKenney" <paulmck@kernel.org>, x86 <x86@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: [tip: core/rcu] rcu: Add a hlist_nulls_unhashed_lockless() function
Date: Sat, 25 Jan 2020 10:42:46 -0000 [thread overview]
Message-ID: <157994896674.396.10350805017692383753.tip-bot2@tip-bot2> (raw)
The following commit has been merged into the core/rcu branch of tip:
Commit-ID: 02b99b38f3d96c77cf0a368d99952aa372dfe58a
Gitweb: https://git.kernel.org/tip/02b99b38f3d96c77cf0a368d99952aa372dfe58a
Author: Paul E. McKenney <paulmck@kernel.org>
AuthorDate: Sat, 09 Nov 2019 10:45:47 -08:00
Committer: Paul E. McKenney <paulmck@kernel.org>
CommitterDate: Fri, 10 Jan 2020 14:00:57 -08:00
rcu: Add a hlist_nulls_unhashed_lockless() function
This commit adds an hlist_nulls_unhashed_lockless() to allow lockless
checking for whether or note an hlist_nulls_node is hashed or not.
While in the area, this commit also adds a docbook comment to the existing
hlist_nulls_unhashed() function.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
include/linux/list_nulls.h | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/include/linux/list_nulls.h b/include/linux/list_nulls.h
index 1ecd356..fa6e847 100644
--- a/include/linux/list_nulls.h
+++ b/include/linux/list_nulls.h
@@ -56,11 +56,33 @@ static inline unsigned long get_nulls_value(const struct hlist_nulls_node *ptr)
return ((unsigned long)ptr) >> 1;
}
+/**
+ * hlist_nulls_unhashed - Has node been removed and reinitialized?
+ * @h: Node to be checked
+ *
+ * Not that not all removal functions will leave a node in unhashed state.
+ * For example, hlist_del_init_rcu() leaves the node in unhashed state,
+ * but hlist_nulls_del() does not.
+ */
static inline int hlist_nulls_unhashed(const struct hlist_nulls_node *h)
{
return !h->pprev;
}
+/**
+ * hlist_nulls_unhashed_lockless - Has node been removed and reinitialized?
+ * @h: Node to be checked
+ *
+ * Not that not all removal functions will leave a node in unhashed state.
+ * For example, hlist_del_init_rcu() leaves the node in unhashed state,
+ * but hlist_nulls_del() does not. Unlike hlist_nulls_unhashed(), this
+ * function may be used locklessly.
+ */
+static inline int hlist_nulls_unhashed_lockless(const struct hlist_nulls_node *h)
+{
+ return !READ_ONCE(h->pprev);
+}
+
static inline int hlist_nulls_empty(const struct hlist_nulls_head *h)
{
return is_a_nulls(READ_ONCE(h->first));
reply other threads:[~2020-01-25 10:43 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=157994896674.396.10350805017692383753.tip-bot2@tip-bot2 \
--to=tip-bot2@linutronix.de \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=paulmck@kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).