From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joel Fernandes Subject: Re: [PATCH] kernel: audit.c: Add __rcu notation to RCU pointer Date: Tue, 26 Nov 2019 21:29:25 -0500 Message-ID: <20191127022925.GB157739@google.com> References: <20191126172723.GA12759@workstation-kernel-dev> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20191126172723.GA12759@workstation-kernel-dev> Sender: linux-kernel-owner@vger.kernel.org To: Amol Grover Cc: Paul Moore , Eric Paris , linux-kernel-mentees@lists.linuxfoundation.org, Shuah Khan , linux-audit@redhat.com, linux-kernel@vger.kernel.org List-Id: linux-audit@redhat.com On Tue, Nov 26, 2019 at 10:57:23PM +0530, Amol Grover wrote: > add __rcu notation to RCU protected global pointer auditd_conn > > Fixes multiple instances of sparse error: > error: incompatible types in comparison expression > (different address spaces) > > Signed-off-by: Amol Grover > --- > kernel/audit.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/kernel/audit.c b/kernel/audit.c > index da8dc0db5bd3..30e7fc9b8da2 100644 > --- a/kernel/audit.c > +++ b/kernel/audit.c > @@ -102,12 +102,14 @@ 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; > +RCU_INIT_POINTER(auditd_conn); Looks like this causes a build error. Always please build test your patches in the very least. And I also did not understand how RCU_INIT_POINTER can even be used outside of a function. In C, executable code cannot be outside functions. Is doing the following not sufficient to fix the sparse issue? thanks, - Joel ---8<----------------------- diff --git a/kernel/audit.c b/kernel/audit.c index 49b6049b26ac..c5d4b5a2dea1 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -108,8 +108,8 @@ struct auditd_connection { struct net *net; struct rcu_head rcu; }; -static struct auditd_connection __rcu *auditd_conn; -RCU_INIT_POINTER(auditd_conn); +static struct auditd_connection __rcu *auditd_conn = NULL; + static DEFINE_SPINLOCK(auditd_conn_lock); /* If audit_rate_limit is non-zero, limit the rate of sending audit records