From: Amol Grover <frextrite@gmail.com>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: Paul Moore <paul@paul-moore.com>, Eric Paris <eparis@redhat.com>,
linux-kernel-mentees@lists.linuxfoundation.org,
Shuah Khan <skhan@linuxfoundation.org>,
linux-audit@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kernel: audit.c: Add __rcu notation to RCU pointer
Date: Wed, 27 Nov 2019 10:58:27 +0530 [thread overview]
Message-ID: <20191127052827.GA9782@workstation-portable> (raw)
In-Reply-To: <20191127022925.GB157739@google.com>
On Tue, Nov 26, 2019 at 09:29:25PM -0500, Joel Fernandes wrote:
> 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 <frextrite@gmail.com>
> > ---
> > 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;
I ran a quick checkpatch and it gave me this error:
ERROR: do not initialise statics to NULL
So in order to fix it I decided to INIT the pointer (and failed)
Should I consider this as a false positive?
Thanks
Amol
> +
> static DEFINE_SPINLOCK(auditd_conn_lock);
>
> /* If audit_rate_limit is non-zero, limit the rate of sending audit records
next prev parent reply other threads:[~2019-11-27 5:29 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-26 17:27 [PATCH] kernel: audit.c: Add __rcu notation to RCU pointer Amol Grover
2019-11-27 2:29 ` Joel Fernandes
2019-11-27 5:28 ` Amol Grover [this message]
2019-11-27 15:25 ` Joel Fernandes
2019-11-28 15:09 ` Amol Grover
2019-11-29 20:08 ` Joel Fernandes
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