linux-kernel - Re: [tipc-discussion] [PATCH net/tipc] Replace rcu_swap_protected() with rcu_replace

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Message-ID: <20191211031751.GZ2889@paulmck-ThinkPad-P72>
Date:   Tue, 10 Dec 2019 19:17:51 -0800
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Tuong Lien Tong <tuong.t.lien@...tech.com.au>
Cc:     'Ying Xue' <ying.xue@...driver.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, mingo@...nel.org,
        tipc-discussion@...ts.sourceforge.net, kernel-team@...com,
        torvalds@...ux-foundation.org, davem@...emloft.net
Subject: Re: [tipc-discussion] [PATCH net/tipc] Replace rcu_swap_protected()
 with rcu_replace_pointer()

On Wed, Dec 11, 2019 at 09:00:39AM +0700, Tuong Lien Tong wrote:
> Hi Ying, Paul,
> 
> Please see my comments inline. Thanks!

Good catch!

> BR/Tuong
> 
> -----Original Message-----
> From: Ying Xue <ying.xue@...driver.com> 
> Sent: Wednesday, December 11, 2019 8:32 AM
> To: paulmck@...nel.org
> Cc: netdev@...r.kernel.org; linux-kernel@...r.kernel.org; mingo@...nel.org;
> tipc-discussion@...ts.sourceforge.net; kernel-team@...com;
> torvalds@...ux-foundation.org; davem@...emloft.net
> Subject: Re: [tipc-discussion] [PATCH net/tipc] Replace rcu_swap_protected()
> with rcu_replace_pointer()
> 
> On 12/11/19 6:38 AM, Paul E. McKenney wrote:
> > commit 4ee8e2c68b076867b7a5af82a38010fffcab611c
> > Author: Paul E. McKenney <paulmck@...nel.org>
> > Date:   Mon Dec 9 19:13:45 2019 -0800
> > 
> >     net/tipc: Replace rcu_swap_protected() with rcu_replace_pointer()
> >     
> >     This commit replaces the use of rcu_swap_protected() with the more
> >     intuitively appealing rcu_replace_pointer() as a step towards removing
> >     rcu_swap_protected().
> >     
> >     Link:
> https://lore.kernel.org/lkml/CAHk-=wiAsJLw1egFEE=Z7-GGtM6wcvtyytXZA1+BHqta4g
> g6Hw@...l.gmail.com/
> >     Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
> >     Reported-by: kbuild test robot <lkp@...el.com>
> >     Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> >     Cc: Jon Maloy <jon.maloy@...csson.com>
> >     Cc: Ying Xue <ying.xue@...driver.com>
> >     Cc: "David S. Miller" <davem@...emloft.net>
> >     Cc: <netdev@...r.kernel.org>
> >     Cc: <tipc-discussion@...ts.sourceforge.net>
> 
> Acked-by: Ying Xue <ying.xue@...driver.com>

As in the following?  If so, I will be very happy to apply your Acked-by.

							Thanx, Paul

------------------------------------------------------------------------

commit 4c0855120704e7a578dc6862ae57babf6dc9bc77
Author: Paul E. McKenney <paulmck@...nel.org>
Date:   Mon Dec 9 19:13:45 2019 -0800

    net/tipc: Replace rcu_swap_protected() with rcu_replace_pointer()
    
    This commit replaces the use of rcu_swap_protected() with the more
    intuitively appealing rcu_replace_pointer() as a step towards removing
    rcu_swap_protected().
    
    Link: https://lore.kernel.org/lkml/CAHk-=wiAsJLw1egFEE=Z7-GGtM6wcvtyytXZA1+BHqta4gg6Hw@mail.gmail.com/
    Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
    Reported-by: kbuild test robot <lkp@...el.com>
    Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
    [ paulmck: Updated based on Ying Xue and Tuong Lien Tong feedback. ]
    Cc: Jon Maloy <jon.maloy@...csson.com>
    Cc: Ying Xue <ying.xue@...driver.com>
    Cc: "David S. Miller" <davem@...emloft.net>
    Cc: <netdev@...r.kernel.org>
    Cc: <tipc-discussion@...ts.sourceforge.net>

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index 990a872..39a13b4 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -258,7 +258,7 @@ static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
 	rcu_dereference_protected((rcu_ptr), lockdep_is_held(lock))
 
 #define tipc_aead_rcu_swap(rcu_ptr, ptr, lock)				\
-	rcu_swap_protected((rcu_ptr), (ptr), lockdep_is_held(lock))
+	rcu_replace_pointer((rcu_ptr), (ptr), lockdep_is_held(lock))
 
 #define tipc_aead_rcu_replace(rcu_ptr, ptr, lock)			\
 do {									\
@@ -1189,7 +1189,7 @@ static bool tipc_crypto_key_try_align(struct tipc_crypto *rx, u8 new_pending)
 
 	/* Move passive key if any */
 	if (key.passive) {
-		tipc_aead_rcu_swap(rx->aead[key.passive], tmp2, &rx->lock);
+		tmp2 = tipc_aead_rcu_swap(rx->aead[key.passive], tmp2, &rx->lock);
 		x = (key.passive - key.pending + new_pending) % KEY_MAX;
 		new_passive = (x <= 0) ? x + KEY_MAX : x;
 	}