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

[Joel Fernandes <joel@joelfernandes.org>]

On Mon, Dec 02, 2019 at 06:24:29PM -0500, Paul Moore wrote:
> On Mon, Dec 2, 2019 at 4:19 PM Joel Fernandes <joel@joelfernandes.org> 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@vger.kernel.org
> >
> > 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.

Sounds good, thanks!

 - Joel


> > 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@joelfernandes.org>
> > > Signed-off-by: Amol Grover <frextrite@gmail.com>
> > > ---
> > > 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