Messages in this thread | | | Subject | Re: [PATCH] rcu: Remove the unnecessary separate function, rcu_preempt_do_callback() | From | Byungchul Park <> | Date | Tue, 27 Feb 2018 08:35:48 +0900 |
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On 2/27/2018 3:22 AM, Paul E. McKenney wrote: > On Mon, Feb 26, 2018 at 12:15:14PM -0500, Steven Rostedt wrote: >> On Mon, 26 Feb 2018 14:11:36 +0900 >> Byungchul Park <byungchul.park@lge.com> wrote: >> >>> rcu_preemptp_do_callback() was introduced in commit 09223371dea(rcu: >>> Use softirq to address performance regression), where it had to be >>> distinguished between in the case CONFIG_TREE_PREEMPT_RCU is set and >>> it's not. >>> >>> Now that the code was cleaned up so that rcu_preemt_do_callback() is >>> only called in rcu_kthread_do_work() in the same file, tree_plugin.h, >>> we don't have to keep the separate function anymore. Remove it for a >>> better readability. >> >> Looks good to me (looks like commit f8b7fc6b51 "rcu: use softirq >> instead of kthreads except when RCU_BOOST=y" cleaned up the ifdefs and >> removed the requirement). >> >> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> > > Thank you both! I have queued a slightly modified patch for testing > and further review. Please see below and let me know if I messed > something up. > > Thanx, Paul > > ------------------------------------------------------------------------ > > commit b8a3012ddba397d4a18d9fd4a00432f8c2626bd6 > Author: Byungchul Park <byungchul.park@lge.com> > Date: Mon Feb 26 14:11:36 2018 +0900 > > rcu: Inline rcu_preempt_do_callback() into its sole caller > > 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. ] > > diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h > index dc6f2319fc21..9dd0ea77faed 100644 > --- a/kernel/rcu/tree.h > +++ b/kernel/rcu/tree.h > @@ -449,7 +449,6 @@ 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 26d7a31e81cb..b0d7f9ba6bf2 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -686,15 +686,6 @@ 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. > @@ -1170,7 +1161,7 @@ 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));
OMG. Sorry for the mistake and thank you very much for fixing it.
I will be more careful.
-- Thanks, Byungchul
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