[net/tipc] Replace rcu_swap_protected() with rcu_replace_pointer()
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Message ID 20191210033146.GA32522@paulmck-ThinkPad-P72
State New
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  • [net/tipc] Replace rcu_swap_protected() with rcu_replace_pointer()
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Commit Message

Paul E. McKenney Dec. 10, 2019, 3:31 a.m. UTC
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@linux-foundation.org>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Jon Maloy <jon.maloy@ericsson.com>
Cc: Ying Xue <ying.xue@windriver.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: <netdev@vger.kernel.org>
Cc: <tipc-discussion@lists.sourceforge.net>

Comments

Ying Xue Dec. 10, 2019, 2:36 p.m. UTC | #1
On 12/10/19 11:31 AM, Paul E. McKenney wrote:
> 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@linux-foundation.org>
> Reported-by: kbuild test robot <lkp@intel.com>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> Cc: Jon Maloy <jon.maloy@ericsson.com>
> Cc: Ying Xue <ying.xue@windriver.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: <netdev@vger.kernel.org>
> Cc: <tipc-discussion@lists.sourceforge.net>
> 
> diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
> index 990a872..64cf831 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))

(ptr) = 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 = rcu_replace_pointer(rx->aead[key.passive], tmp2, &rx->lock);

tipc_aead_rcu_swap() is only called here in TIPC module. If we use
rcu_replace_pointer() to switch pointers instead of calling
tipc_aead_rcu_swap() macro, I think we should completely remove
tipc_aead_rcu_swap().

>  		x = (key.passive - key.pending + new_pending) % KEY_MAX;
>  		new_passive = (x <= 0) ? x + KEY_MAX : x;
>  	}
>
Paul E. McKenney Dec. 10, 2019, 10:38 p.m. UTC | #2
On Tue, Dec 10, 2019 at 10:36:59PM +0800, Ying Xue wrote:
> On 12/10/19 11:31 AM, Paul E. McKenney wrote:
> > 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@linux-foundation.org>
> > Reported-by: kbuild test robot <lkp@intel.com>
> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> > Cc: Jon Maloy <jon.maloy@ericsson.com>
> > Cc: Ying Xue <ying.xue@windriver.com>
> > Cc: "David S. Miller" <davem@davemloft.net>
> > Cc: <netdev@vger.kernel.org>
> > Cc: <tipc-discussion@lists.sourceforge.net>
> > 
> > diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
> > index 990a872..64cf831 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))
> 
> (ptr) = 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 = rcu_replace_pointer(rx->aead[key.passive], tmp2, &rx->lock);
> 
> tipc_aead_rcu_swap() is only called here in TIPC module. If we use
> rcu_replace_pointer() to switch pointers instead of calling
> tipc_aead_rcu_swap() macro, I think we should completely remove
> tipc_aead_rcu_swap().

Good catch, thank you!  How about the following instead?

							Thanx, Paul

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

commit 4ee8e2c68b076867b7a5af82a38010fffcab611c
Author: Paul E. McKenney <paulmck@kernel.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@linux-foundation.org>
    Reported-by: kbuild test robot <lkp@intel.com>
    Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
    Cc: Jon Maloy <jon.maloy@ericsson.com>
    Cc: Ying Xue <ying.xue@windriver.com>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: <netdev@vger.kernel.org>
    Cc: <tipc-discussion@lists.sourceforge.net>

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index 990a872..978d2db 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -257,9 +257,6 @@ static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
 #define tipc_aead_rcu_ptr(rcu_ptr, lock)				\
 	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))
-
 #define tipc_aead_rcu_replace(rcu_ptr, ptr, lock)			\
 do {									\
 	typeof(rcu_ptr) __tmp = rcu_dereference_protected((rcu_ptr),	\
@@ -1189,7 +1186,7 @@ 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 = rcu_replace_pointer(rx->aead[key.passive], tmp2, &rx->lock);
 		x = (key.passive - key.pending + new_pending) % KEY_MAX;
 		new_passive = (x <= 0) ? x + KEY_MAX : x;
 	}
Ying Xue Dec. 11, 2019, 1:31 a.m. UTC | #3
On 12/11/19 6:38 AM, Paul E. McKenney wrote:
> commit 4ee8e2c68b076867b7a5af82a38010fffcab611c
> Author: Paul E. McKenney <paulmck@kernel.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@linux-foundation.org>
>     Reported-by: kbuild test robot <lkp@intel.com>
>     Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
>     Cc: Jon Maloy <jon.maloy@ericsson.com>
>     Cc: Ying Xue <ying.xue@windriver.com>
>     Cc: "David S. Miller" <davem@davemloft.net>
>     Cc: <netdev@vger.kernel.org>
>     Cc: <tipc-discussion@lists.sourceforge.net>
> 

Acked-by: Ying Xue <ying.xue@windriver.com>

> diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
> index 990a872..978d2db 100644
> --- a/net/tipc/crypto.c
> +++ b/net/tipc/crypto.c
> @@ -257,9 +257,6 @@ static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
>  #define tipc_aead_rcu_ptr(rcu_ptr, lock)				\
>  	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))
> -
>  #define tipc_aead_rcu_replace(rcu_ptr, ptr, lock)			\
>  do {									\
>  	typeof(rcu_ptr) __tmp = rcu_dereference_protected((rcu_ptr),	\
> @@ -1189,7 +1186,7 @@ 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 = rcu_replace_pointer(rx->aead[key.passive], tmp2, &rx->lock);
>  		x = (key.passive - key.pending + new_pending) % KEY_MAX;
>  		new_passive = (x <= 0) ? x + KEY_MAX : x;
>  	}
>
Tuong Lien Tong Dec. 11, 2019, 2 a.m. UTC | #4
Hi Ying, Paul,

Please see my comments inline. Thanks!

BR/Tuong

-----Original Message-----
From: Ying Xue <ying.xue@windriver.com> 
Sent: Wednesday, December 11, 2019 8:32 AM
To: paulmck@kernel.org
Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; mingo@kernel.org;
tipc-discussion@lists.sourceforge.net; kernel-team@fb.com;
torvalds@linux-foundation.org; davem@davemloft.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@kernel.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@mail.gmail.com/
>     Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
>     Reported-by: kbuild test robot <lkp@intel.com>
>     Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
>     Cc: Jon Maloy <jon.maloy@ericsson.com>
>     Cc: Ying Xue <ying.xue@windriver.com>
>     Cc: "David S. Miller" <davem@davemloft.net>
>     Cc: <netdev@vger.kernel.org>
>     Cc: <tipc-discussion@lists.sourceforge.net>
> 

Acked-by: Ying Xue <ying.xue@windriver.com>

> diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
> index 990a872..978d2db 100644
> --- a/net/tipc/crypto.c
> +++ b/net/tipc/crypto.c
> @@ -257,9 +257,6 @@ static char *tipc_key_change_dump(struct tipc_key old,
struct tipc_key new,
>  #define tipc_aead_rcu_ptr(rcu_ptr, lock)				\
>  	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))
> -
>  #define tipc_aead_rcu_replace(rcu_ptr, ptr, lock)			\
>  do {									\
>  	typeof(rcu_ptr) __tmp = rcu_dereference_protected((rcu_ptr),	\
> @@ -1189,7 +1186,7 @@ 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 = rcu_replace_pointer(rx->aead[key.passive], tmp2,
&rx->lock);
The 3rd parameter should be the lockdep condition checking instead of the
spinlock's pointer i.e. "lockdep_is_held(&rx->lock)"?
That's why I'd prefer to use the 'tipc_aead_rcu_swap ()' macro, which is
clear & concise at least for the context here. It might be re-used later as
well...

>  		x = (key.passive - key.pending + new_pending) % KEY_MAX;
>  		new_passive = (x <= 0) ? x + KEY_MAX : x;
>  	}
>
Paul E. McKenney Dec. 11, 2019, 3:17 a.m. UTC | #5
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@windriver.com> 
> Sent: Wednesday, December 11, 2019 8:32 AM
> To: paulmck@kernel.org
> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; mingo@kernel.org;
> tipc-discussion@lists.sourceforge.net; kernel-team@fb.com;
> torvalds@linux-foundation.org; davem@davemloft.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@kernel.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@mail.gmail.com/
> >     Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> >     Reported-by: kbuild test robot <lkp@intel.com>
> >     Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> >     Cc: Jon Maloy <jon.maloy@ericsson.com>
> >     Cc: Ying Xue <ying.xue@windriver.com>
> >     Cc: "David S. Miller" <davem@davemloft.net>
> >     Cc: <netdev@vger.kernel.org>
> >     Cc: <tipc-discussion@lists.sourceforge.net>
> 
> Acked-by: Ying Xue <ying.xue@windriver.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@kernel.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@linux-foundation.org>
    Reported-by: kbuild test robot <lkp@intel.com>
    Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
    [ paulmck: Updated based on Ying Xue and Tuong Lien Tong feedback. ]
    Cc: Jon Maloy <jon.maloy@ericsson.com>
    Cc: Ying Xue <ying.xue@windriver.com>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: <netdev@vger.kernel.org>
    Cc: <tipc-discussion@lists.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;
 	}
Ying Xue Dec. 11, 2019, 4:35 a.m. UTC | #6
On 12/11/19 11:17 AM, Paul E. McKenney wrote:
>> Acked-by: Ying Xue <ying.xue@windriver.com>
> As in the following?  If so, I will be very happy to apply your Acked-by.

Yes. Thanks!
Ying Xue Dec. 11, 2019, 4:42 a.m. UTC | #7
On 12/11/19 10:00 AM, Tuong Lien Tong wrote:
>>  
>>  	/* Move passive key if any */
>>  	if (key.passive) {
>> -		tipc_aead_rcu_swap(rx->aead[key.passive], tmp2, &rx->lock);
>> +		tmp2 = rcu_replace_pointer(rx->aead[key.passive], tmp2,
> &rx->lock);
> The 3rd parameter should be the lockdep condition checking instead of the
> spinlock's pointer i.e. "lockdep_is_held(&rx->lock)"?
> That's why I'd prefer to use the 'tipc_aead_rcu_swap ()' macro, which is
> clear & concise at least for the context here. It might be re-used later as
> well...
> 

Right. The 3rd parameter of rcu_replace_pointer() should be
"lockdep_is_held(&rx->lock)" instead of "&rx->lock".
Paul E. McKenney Dec. 11, 2019, 6:46 p.m. UTC | #8
On Wed, Dec 11, 2019 at 12:42:00PM +0800, Ying Xue wrote:
> On 12/11/19 10:00 AM, Tuong Lien Tong wrote:
> >>  
> >>  	/* Move passive key if any */
> >>  	if (key.passive) {
> >> -		tipc_aead_rcu_swap(rx->aead[key.passive], tmp2, &rx->lock);
> >> +		tmp2 = rcu_replace_pointer(rx->aead[key.passive], tmp2,
> > &rx->lock);
> > The 3rd parameter should be the lockdep condition checking instead of the
> > spinlock's pointer i.e. "lockdep_is_held(&rx->lock)"?
> > That's why I'd prefer to use the 'tipc_aead_rcu_swap ()' macro, which is
> > clear & concise at least for the context here. It might be re-used later as
> > well...
> > 
> 
> Right. The 3rd parameter of rcu_replace_pointer() should be
> "lockdep_is_held(&rx->lock)" instead of "&rx->lock".

Like this?

							Thanx, Paul

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

commit 575bb4ba1b22383656760feb3d122e11656ccdfd
Author: Paul E. McKenney <paulmck@kernel.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@linux-foundation.org>
    Reported-by: kbuild test robot <lkp@intel.com>
    Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
    [ paulmck: Updated based on Ying Xue and Tuong Lien Tong feedback. ]
    Cc: Jon Maloy <jon.maloy@ericsson.com>
    Cc: Ying Xue <ying.xue@windriver.com>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: <netdev@vger.kernel.org>
    Cc: <tipc-discussion@lists.sourceforge.net>

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index 990a872..c8c47fc 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -257,9 +257,6 @@ static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
 #define tipc_aead_rcu_ptr(rcu_ptr, lock)				\
 	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))
-
 #define tipc_aead_rcu_replace(rcu_ptr, ptr, lock)			\
 do {									\
 	typeof(rcu_ptr) __tmp = rcu_dereference_protected((rcu_ptr),	\
@@ -1189,7 +1186,7 @@ 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 = rcu_replace_pointer(rx->aead[key.passive], tmp2, lockdep_is_held(&rx->lock));
 		x = (key.passive - key.pending + new_pending) % KEY_MAX;
 		new_passive = (x <= 0) ? x + KEY_MAX : x;
 	}
Ying Xue Dec. 12, 2019, 6:14 a.m. UTC | #9
On 12/12/19 2:46 AM, Paul E. McKenney wrote:
> On Wed, Dec 11, 2019 at 12:42:00PM +0800, Ying Xue wrote:
>> On 12/11/19 10:00 AM, Tuong Lien Tong wrote:
>>>>  
>>>>  	/* Move passive key if any */
>>>>  	if (key.passive) {
>>>> -		tipc_aead_rcu_swap(rx->aead[key.passive], tmp2, &rx->lock);
>>>> +		tmp2 = rcu_replace_pointer(rx->aead[key.passive], tmp2,
>>> &rx->lock);
>>> The 3rd parameter should be the lockdep condition checking instead of the
>>> spinlock's pointer i.e. "lockdep_is_held(&rx->lock)"?
>>> That's why I'd prefer to use the 'tipc_aead_rcu_swap ()' macro, which is
>>> clear & concise at least for the context here. It might be re-used later as
>>> well...
>>>
>>
>> Right. The 3rd parameter of rcu_replace_pointer() should be
>> "lockdep_is_held(&rx->lock)" instead of "&rx->lock".
> 
> Like this?

Yes, I think it's better to set the 3rd parameter of
rcu_replace_pointer() with "lockdep_is_held(&rx->lock)".

> 
> 							Thanx, Paul
> 
> ------------------------------------------------------------------------
> 
> commit 575bb4ba1b22383656760feb3d122e11656ccdfd
> Author: Paul E. McKenney <paulmck@kernel.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@linux-foundation.org>
>     Reported-by: kbuild test robot <lkp@intel.com>
>     Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
>     [ paulmck: Updated based on Ying Xue and Tuong Lien Tong feedback. ]
>     Cc: Jon Maloy <jon.maloy@ericsson.com>
>     Cc: Ying Xue <ying.xue@windriver.com>
>     Cc: "David S. Miller" <davem@davemloft.net>
>     Cc: <netdev@vger.kernel.org>
>     Cc: <tipc-discussion@lists.sourceforge.net>
> 
> diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
> index 990a872..c8c47fc 100644
> --- a/net/tipc/crypto.c
> +++ b/net/tipc/crypto.c
> @@ -257,9 +257,6 @@ static char *tipc_key_change_dump(struct tipc_key old, struct tipc_key new,
>  #define tipc_aead_rcu_ptr(rcu_ptr, lock)				\
>  	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))
> -
>  #define tipc_aead_rcu_replace(rcu_ptr, ptr, lock)			\
>  do {									\
>  	typeof(rcu_ptr) __tmp = rcu_dereference_protected((rcu_ptr),	\
> @@ -1189,7 +1186,7 @@ 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 = rcu_replace_pointer(rx->aead[key.passive], tmp2, lockdep_is_held(&rx->lock));
>  		x = (key.passive - key.pending + new_pending) % KEY_MAX;
>  		new_passive = (x <= 0) ? x + KEY_MAX : x;
>  	}
>

Patch
diff mbox series

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index 990a872..64cf831 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 = rcu_replace_pointer(rx->aead[key.passive], tmp2, &rx->lock);
 		x = (key.passive - key.pending + new_pending) % KEY_MAX;
 		new_passive = (x <= 0) ? x + KEY_MAX : x;
 	}