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From: Jan Kara <jack@suse.cz>
To: linux-audit@redhat.com
Cc: Paul Moore <paul@paul-moore.com>, <linux-fsdevel@vger.kernel.org>,
	Al Viro <viro@ZenIV.linux.org.uk>,
	Richard Guy Briggs <rgb@redhat.com>,
	Amir Goldstein <amir73il@gmail.com>, Jan Kara <jack@suse.cz>
Subject: [PATCH 08/10] audit: Provide helper for dropping mark's chunk reference
Date: Tue, 10 Jul 2018 12:02:14 +0200	[thread overview]
Message-ID: <20180710100217.12866-9-jack@suse.cz> (raw)
In-Reply-To: <20180710100217.12866-1-jack@suse.cz>

Provide a helper function audit_mark_put_chunk() for dropping mark's
reference (which has to happen only after RCU grace period expires).
Currently that happens only from a single place but in later patches we
introduce more callers.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 kernel/audit_tree.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index b7977cf30479..bce3b04a365d 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -132,10 +132,20 @@ static void __put_chunk(struct rcu_head *rcu)
 	audit_put_chunk(chunk);
 }
 
+/*
+ * Drop reference to the chunk that was held by the mark. This is the reference
+ * that gets dropped after we've removed the chunk from the hash table and we
+ * use it to make sure chunk cannot be freed before RCU grace period expires.
+ */
+static void audit_mark_put_chunk(struct audit_chunk *chunk)
+{
+	call_rcu(&chunk->head, __put_chunk);
+}
+
 static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
 {
 	struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
-	call_rcu(&chunk->head, __put_chunk);
+	audit_mark_put_chunk(chunk);
 }
 
 static struct audit_chunk *alloc_chunk(int count)
-- 
2.16.4

  parent reply	other threads:[~2018-07-10 10:02 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-10 10:02 [PATCH 0/10 v2] audit: Fix various races when tagging and untagging mounts Jan Kara
2018-07-10 10:02 ` [PATCH 01/10] audit_tree: Remove mark->lock locking Jan Kara
2018-07-27  4:47   ` Paul Moore
2018-09-04  9:53     ` Jan Kara
2018-07-10 10:02 ` [PATCH 02/10] audit: Fix possible spurious -ENOSPC error Jan Kara
2018-07-27  4:47   ` Paul Moore
2018-09-04 10:00     ` Jan Kara
2018-07-10 10:02 ` [PATCH 03/10] audit: Fix possible tagging failures Jan Kara
2018-07-10 10:02 ` [PATCH 04/10] audit: Embed key into chunk Jan Kara
2018-07-27  4:47   ` Paul Moore
2018-07-10 10:02 ` [PATCH 05/10] audit: Make hash table insertion safe against concurrent lookups Jan Kara
2018-07-10 10:02 ` [PATCH 06/10] audit: Factor out chunk replacement code Jan Kara
2018-07-11  7:58   ` Amir Goldstein
2018-07-11  8:26     ` Jan Kara
2018-07-11  9:01       ` Amir Goldstein
2018-07-11  9:23         ` Jan Kara
2018-07-27  4:47   ` Paul Moore
2018-07-10 10:02 ` [PATCH 07/10] audit: Remove pointless check in insert_hash() Jan Kara
2018-07-27  4:47   ` Paul Moore
2018-07-10 10:02 ` Jan Kara [this message]
2018-07-10 10:02 ` [PATCH 09/10] audit: Allocate fsnotify mark independently of chunk Jan Kara
2018-07-11  8:57   ` Amir Goldstein
2018-07-11 10:48     ` Amir Goldstein
2018-07-16 15:13       ` Jan Kara
2018-07-27  4:47   ` Paul Moore
2018-09-04 14:03     ` Jan Kara
2018-09-04 14:07       ` Jan Kara
2018-07-10 10:02 ` [PATCH 10/10] audit: Replace chunk attached to mark instead of replacing mark Jan Kara
2018-07-11 14:17   ` Amir Goldstein
2018-07-27  4:47   ` Paul Moore
2018-09-04 14:11     ` Jan Kara
2018-07-10 10:02 ` [PATCH 11/10 TESTSUITE] audit_testsuite: Add stress test for tree watches Jan Kara

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