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    Subject[PATCH tip/core/rcu 02/22] rcu: Inline rcu_preempt_do_callback() into its sole caller
    Date
    From: Byungchul Park <byungchul.park@lge.com>

    The rcu_preempt_do_callbacks() function was introduced in commit
    09223371dea(rcu: Use softirq to address performance regression), where it
    was necessary to handle kernel builds both containing and not containing
    RCU-preempt. Since then, various changes (most notably f8b7fc6b51
    ("rcu: use softirq instead of kthreads except when RCU_BOOST=y")) have
    resulted in this function being invoked only from rcu_kthread_do_work(),
    which is present only in kernels containing RCU-preempt, which in turn
    means that the rcu_preempt_do_callbacks() function is no longer needed.

    This commit therefore inlines rcu_preempt_do_callbacks() into its
    sole remaining caller and also removes the rcu_state_p and rcu_data_p
    indirection for added clarity.

    Signed-off-by: Byungchul Park <byungchul.park@lge.com>
    Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
    [ paulmck: Remove the rcu_state_p and rcu_data_p indirection. ]
    Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    ---
    kernel/rcu/tree.h | 1 -
    kernel/rcu/tree_plugin.h | 11 +----------
    2 files changed, 1 insertion(+), 11 deletions(-)

    diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
    index f491ab4f2e8e..3a0dc30100e8 100644
    --- a/kernel/rcu/tree.h
    +++ b/kernel/rcu/tree.h
    @@ -438,7 +438,6 @@ static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
    static void invoke_rcu_callbacks_kthread(void);
    static bool rcu_is_callbacks_kthread(void);
    #ifdef CONFIG_RCU_BOOST
    -static void rcu_preempt_do_callbacks(void);
    static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
    struct rcu_node *rnp);
    #endif /* #ifdef CONFIG_RCU_BOOST */
    diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
    index 84fbee4686d3..6c5df18bbf2f 100644
    --- a/kernel/rcu/tree_plugin.h
    +++ b/kernel/rcu/tree_plugin.h
    @@ -685,15 +685,6 @@ static void rcu_preempt_check_callbacks(void)
    t->rcu_read_unlock_special.b.need_qs = true;
    }

    -#ifdef CONFIG_RCU_BOOST
    -
    -static void rcu_preempt_do_callbacks(void)
    -{
    - rcu_do_batch(rcu_state_p, this_cpu_ptr(rcu_data_p));
    -}
    -
    -#endif /* #ifdef CONFIG_RCU_BOOST */
    -
    /**
    * call_rcu() - Queue an RCU callback for invocation after a grace period.
    * @head: structure to be used for queueing the RCU updates.
    @@ -1140,7 +1131,7 @@ static void rcu_kthread_do_work(void)
    {
    rcu_do_batch(&rcu_sched_state, this_cpu_ptr(&rcu_sched_data));
    rcu_do_batch(&rcu_bh_state, this_cpu_ptr(&rcu_bh_data));
    - rcu_preempt_do_callbacks();
    + rcu_do_batch(&rcu_preempt_state, this_cpu_ptr(&rcu_preempt_data));
    }

    static void rcu_cpu_kthread_setup(unsigned int cpu)
    --
    2.5.2
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