Messages in this thread | | | Date | Thu, 16 Apr 2020 21:44:13 +0000 | From | Wei Yang <> | Subject | Re: [PATCH] rcu: init and destroy rcu_synchronize when necessary |
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On Wed, Apr 15, 2020 at 05:24:00PM -0700, Paul E. McKenney wrote: >On Wed, Apr 15, 2020 at 10:26:55PM +0000, Wei Yang wrote: >> We would skip the rcu_synchronize if it is a duplicate call back function. >> >> This is not necessary to init and destroy for them. >> >> Signed-off-by: Wei Yang <richard.weiyang@gmail.com> > >Applied, thank you! > >I edited the commit log a bit. Could you please check below to make >sure that I didn't mess anything up? >
Yep, the changelog looks good to me :-)
Glad you like it.
> Thanx, Paul > >------------------------------------------------------------------------ > >commit d9eaddf545fe8e3e2725e2fa0bf87b59b5667c14 >Author: Wei Yang <richard.weiyang@gmail.com> >Date: Wed Apr 15 22:26:55 2020 +0000 > > rcu: Initialize and destroy rcu_synchronize only when necessary > > The __wait_rcu_gp() function unconditionally initializes and cleans up > each element of rs_array[], whether used or not. This is slightly > wasteful and rather confusing, so this commit skips both initialization > and cleanup for duplicate callback functions. > > Signed-off-by: Wei Yang <richard.weiyang@gmail.com> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > >diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c >index 3ce63a9..351c322 100644 >--- a/kernel/rcu/update.c >+++ b/kernel/rcu/update.c >@@ -391,13 +391,14 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array, > might_sleep(); > continue; > } >- init_rcu_head_on_stack(&rs_array[i].head); >- init_completion(&rs_array[i].completion); > for (j = 0; j < i; j++) > if (crcu_array[j] == crcu_array[i]) > break; >- if (j == i) >+ if (j == i) { >+ init_rcu_head_on_stack(&rs_array[i].head); >+ init_completion(&rs_array[i].completion); > (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu); >+ } > } > > /* Wait for all callbacks to be invoked. */ >@@ -408,9 +409,10 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array, > for (j = 0; j < i; j++) > if (crcu_array[j] == crcu_array[i]) > break; >- if (j == i) >+ if (j == i) { > wait_for_completion(&rs_array[i].completion); >- destroy_rcu_head_on_stack(&rs_array[i].head); >+ destroy_rcu_head_on_stack(&rs_array[i].head); >+ } > } > } > EXPORT_SYMBOL_GPL(__wait_rcu_gp);
-- Wei Yang Help you, Help me
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