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

[Paul Moore]

On Mon, Dec 2, 2019 at 4:19 PM Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote:
> 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.

FWIW, this looks reasonable to me, but I don't see this as a critical
fix that needs to go in during the merge window.  Unless I see any
objections, I'll plan on merging this into audit/next once the merge
window closes.

> 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
> >



--
paul moore
www.paul-moore.com