Re: [PATCH v3] kernel: audit.c: Add __rcu annotation to RCU pointer

[Joel Fernandes]

Good idea to CC the following on RCU patches:
Paul McKenney
Steven Rostedt
(Any others on the RCU maintainers list).
And, the list: rcu@xxxxxxxxxxxxxxx

Could anyone Ack the patch? Looks safe and straight forward.

On Mon, Dec 02, 2019 at 12:03:48AM +0530, Amol Grover wrote:
> 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@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Amol Grover <frextrite@xxxxxxxxx>
> ---
> v3:
> - update changelog to be more descriptive
> 
> v2:
> - 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
> -- 
> 2.24.0
>