[Linux-kernel-mentees] [PATCH v3] kernel: audit.c: Add __rcu annotation to RCU pointer

Amol Grover frextrite at gmail.com
Sun Dec 1 18:33:48 UTC 2019

Add __rcu annotation to RCU-protected global pointer auditd_conn.

auditd_conn is an RCU-protected global pointer,i.e., accessed
via RCU methods rcu_dereference() and rcu_assign_pointer(),
hence it must be annotated with __rcu for sparse to report
warnings/errors correctly.

Fix multiple instances of the sparse error:
error: incompatible types in comparison expression
(different address spaces)

Reviewed-by: Joel Fernandes (Google) <joel at joelfernandes.org>
Signed-off-by: Amol Grover <frextrite at gmail.com>
- update changelog to be more descriptive

- fix erroneous RCU pointer initialization
 kernel/audit.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index da8dc0db5bd3..ff7cfc61f53d 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -102,12 +102,13 @@ struct audit_net {
  * This struct is RCU protected; you must either hold the RCU lock for reading
  * or the associated spinlock for writing.
-static struct auditd_connection {
+struct auditd_connection {
 	struct pid *pid;
 	u32 portid;
 	struct net *net;
 	struct rcu_head rcu;
-} *auditd_conn = NULL;
+static struct auditd_connection __rcu *auditd_conn;
 static DEFINE_SPINLOCK(auditd_conn_lock);
 /* If audit_rate_limit is non-zero, limit the rate of sending audit records

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