linux-kernel - Re: [PATCH] rcu: add declarations of undeclared items

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Date:   Mon, 14 Oct 2019 13:51:23 -0400
From:   Joel Fernandes <joel@...lfernandes.org>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Ben Dooks <ben.dooks@...ethink.co.uk>,
        linux-kernel@...ts.codethink.co.uk,
        Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>, rcu@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rcu: add declarations of undeclared items

On Fri, Oct 11, 2019 at 09:44:30PM -0700, Paul E. McKenney wrote:
> On Fri, Oct 11, 2019 at 06:08:24PM +0100, Ben Dooks wrote:
> > The rcu_state, rcu_rnp_online_cpus and rcu_dynticks_curr_cpu_in_eqs
> > do not have declarations in a header. Add these to remove the
> > following sparse warnings:
> > 
> > kernel/rcu/tree.c:87:18: warning: symbol 'rcu_state' was not declared. Should it be static?
> > kernel/rcu/tree.c:191:15: warning: symbol 'rcu_rnp_online_cpus' was not declared. Should it be static?
> > kernel/rcu/tree.c:297:6: warning: symbol 'rcu_dynticks_curr_cpu_in_eqs' was not declared. Should it be static?
> > 
> > Signed-off-by: Ben Dooks <ben.dooks@...ethink.co.uk>
> 
> Good catch!
> 
> However, these guys (plus one more) are actually used only in the
> kernel/rcu/tree.o translation unit, so they can be marked static.
> I made this change as shown below with your Reported-by.
> 
> Seem reasonable?
> 

LGTM.

Reviewed-by: Joel Fernandes (Google) <joel@...lfernandes.org>

thanks,

 - Joel

> 							Thanx, Paul
> 
> ------------------------------------------------------------------------
> 
> commit 02995691aa76f3e52599d4f9d9d1ab23c3574f32
> Author: Paul E. McKenney <paulmck@...nel.org>
> Date:   Fri Oct 11 21:40:09 2019 -0700
> 
>     rcu: Mark non-global functions and variables as static
>     
>     Each of rcu_state, rcu_rnp_online_cpus(), rcu_dynticks_curr_cpu_in_eqs(),
>     and rcu_dynticks_snap() are used only in the kernel/rcu/tree.o translation
>     unit, and may thus be marked static.  This commit therefore makes this
>     change.
>     
>     Reported-by: Ben Dooks <ben.dooks@...ethink.co.uk>
>     Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> 
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index b18fa3d..278798e 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -85,7 +85,7 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {
>  	.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
>  	.dynticks = ATOMIC_INIT(RCU_DYNTICK_CTRL_CTR),
>  };
> -struct rcu_state rcu_state = {
> +static struct rcu_state rcu_state = {
>  	.level = { &rcu_state.node[0] },
>  	.gp_state = RCU_GP_IDLE,
>  	.gp_seq = (0UL - 300UL) << RCU_SEQ_CTR_SHIFT,
> @@ -189,7 +189,7 @@ EXPORT_SYMBOL_GPL(rcu_get_gp_kthreads_prio);
>   * held, but the bit corresponding to the current CPU will be stable
>   * in most contexts.
>   */
> -unsigned long rcu_rnp_online_cpus(struct rcu_node *rnp)
> +static unsigned long rcu_rnp_online_cpus(struct rcu_node *rnp)
>  {
>  	return READ_ONCE(rnp->qsmaskinitnext);
>  }
> @@ -295,7 +295,7 @@ static void rcu_dynticks_eqs_online(void)
>   *
>   * No ordering, as we are sampling CPU-local information.
>   */
> -bool rcu_dynticks_curr_cpu_in_eqs(void)
> +static bool rcu_dynticks_curr_cpu_in_eqs(void)
>  {
>  	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
>  
> @@ -306,7 +306,7 @@ bool rcu_dynticks_curr_cpu_in_eqs(void)
>   * Snapshot the ->dynticks counter with full ordering so as to allow
>   * stable comparison of this counter with past and future snapshots.
>   */
> -int rcu_dynticks_snap(struct rcu_data *rdp)
> +static int rcu_dynticks_snap(struct rcu_data *rdp)
>  {
>  	int snap = atomic_add_return(0, &rdp->dynticks);
>  
> diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
> index 1540542..f8e6c70 100644
> --- a/kernel/rcu/tree.h
> +++ b/kernel/rcu/tree.h
> @@ -402,8 +402,6 @@ static const char *tp_rcu_varname __used __tracepoint_string = rcu_name;
>  #define RCU_NAME rcu_name
>  #endif /* #else #ifdef CONFIG_TRACING */
>  
> -int rcu_dynticks_snap(struct rcu_data *rdp);
> -
>  /* Forward declarations for tree_plugin.h */
>  static void rcu_bootup_announce(void);
>  static void rcu_qs(void);