* [PATCH] drivers/crypto: Use RCU_INIT_POINTER(x, NULL) in nx/nx-842.c
@ 2014-03-23 19:32 Monam Agarwal
2014-04-16 13:48 ` Herbert Xu
0 siblings, 1 reply; 7+ messages in thread
From: Monam Agarwal @ 2014-03-23 19:32 UTC (permalink / raw)
To: rcj, mhcerri, fin, herbert, davem, linux-kernel
This patch replaces rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL)
The rcu_assign_pointer() ensures that the initialization of a structure
is carried out before storing a pointer to that structure.
And in the case of the NULL pointer, there is no structure to initialize.
So, rcu_assign_pointer(p, NULL) can be safely converted to RCU_INIT_POINTER(p, NULL)
Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
---
drivers/crypto/nx/nx-842.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/crypto/nx/nx-842.c b/drivers/crypto/nx/nx-842.c
index 1e5481d..c4fcbf4 100644
--- a/drivers/crypto/nx/nx-842.c
+++ b/drivers/crypto/nx/nx-842.c
@@ -1234,7 +1234,7 @@ static int __exit nx842_remove(struct vio_dev *viodev)
old_devdata = rcu_dereference_check(devdata,
lockdep_is_held(&devdata_mutex));
of_reconfig_notifier_unregister(&nx842_of_nb);
- rcu_assign_pointer(devdata, NULL);
+ RCU_INIT_POINTER(devdata, NULL);
spin_unlock_irqrestore(&devdata_mutex, flags);
synchronize_rcu();
dev_set_drvdata(&viodev->dev, NULL);
@@ -1285,7 +1285,7 @@ static void __exit nx842_exit(void)
spin_lock_irqsave(&devdata_mutex, flags);
old_devdata = rcu_dereference_check(devdata,
lockdep_is_held(&devdata_mutex));
- rcu_assign_pointer(devdata, NULL);
+ RCU_INIT_POINTER(devdata, NULL);
spin_unlock_irqrestore(&devdata_mutex, flags);
synchronize_rcu();
if (old_devdata)
--
1.7.9.5
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] drivers/crypto: Use RCU_INIT_POINTER(x, NULL) in nx/nx-842.c
2014-03-23 19:32 [PATCH] drivers/crypto: Use RCU_INIT_POINTER(x, NULL) in nx/nx-842.c Monam Agarwal
@ 2014-04-16 13:48 ` Herbert Xu
0 siblings, 0 replies; 7+ messages in thread
From: Herbert Xu @ 2014-04-16 13:48 UTC (permalink / raw)
To: Monam Agarwal; +Cc: rcj, mhcerri, fin, davem, linux-kernel
On Mon, Mar 24, 2014 at 01:02:42AM +0530, Monam Agarwal wrote:
> This patch replaces rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL)
>
> The rcu_assign_pointer() ensures that the initialization of a structure
> is carried out before storing a pointer to that structure.
> And in the case of the NULL pointer, there is no structure to initialize.
> So, rcu_assign_pointer(p, NULL) can be safely converted to RCU_INIT_POINTER(p, NULL)
>
> Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
Patch applied.
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] drivers/crypto: Use RCU_INIT_POINTER(x, NULL) in nx/nx-842.c
2014-03-24 11:16 ` Neil Horman
@ 2014-03-24 12:03 ` Arend van Spriel
0 siblings, 0 replies; 7+ messages in thread
From: Arend van Spriel @ 2014-03-24 12:03 UTC (permalink / raw)
To: Neil Horman, Monam Agarwal
Cc: rcj, mhcerri, fin, herbert, davem, linux-crypto, linux-kernel
On 24/03/14 12:16, Neil Horman wrote:
> On Mon, Mar 24, 2014 at 01:01:04AM +0530, Monam Agarwal wrote:
>> This patch replaces rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL)
>>
>> The rcu_assign_pointer() ensures that the initialization of a structure
>> is carried out before storing a pointer to that structure.
>> And in the case of the NULL pointer, there is no structure to initialize.
>> So, rcu_assign_pointer(p, NULL) can be safely converted to RCU_INIT_POINTER(p, NULL)
>>
>> Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
>> ---
>> drivers/crypto/nx/nx-842.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/crypto/nx/nx-842.c b/drivers/crypto/nx/nx-842.c
>> index 1e5481d..c4fcbf4 100644
>> --- a/drivers/crypto/nx/nx-842.c
>> +++ b/drivers/crypto/nx/nx-842.c
>> @@ -1234,7 +1234,7 @@ static int __exit nx842_remove(struct vio_dev *viodev)
>> old_devdata = rcu_dereference_check(devdata,
>> lockdep_is_held(&devdata_mutex));
>> of_reconfig_notifier_unregister(&nx842_of_nb);
>> - rcu_assign_pointer(devdata, NULL);
>> + RCU_INIT_POINTER(devdata, NULL);
>> spin_unlock_irqrestore(&devdata_mutex, flags);
>> synchronize_rcu();
>> dev_set_drvdata(&viodev->dev, NULL);
>> @@ -1285,7 +1285,7 @@ static void __exit nx842_exit(void)
>> spin_lock_irqsave(&devdata_mutex, flags);
>> old_devdata = rcu_dereference_check(devdata,
>> lockdep_is_held(&devdata_mutex));
>> - rcu_assign_pointer(devdata, NULL);
>> + RCU_INIT_POINTER(devdata, NULL);
>> spin_unlock_irqrestore(&devdata_mutex, flags);
>> synchronize_rcu();
>> if (old_devdata)
>
> This really does't seem right. rcu_assign_pointer users ACCESS_ONCE to protect
> against multiple loads that allow for concurrent read/write use with parallel
> rcu_dereference calls, whereas RCU_INIT_POINTER does not. It also just doesn't
> look right. We've already initalized the pointerin nx842_init, we don't need to
> re-initalize it here, we need to assign it to NULL.
I was being cautious as well, but Paul gave me an explanation [1]
Hope it helps you as well ;-)
But I think I also saw a patch that modifies rcu_assign_pointer to
handle NULL assignment. Don't recall the thread.
Regards,
Arend
[1] http://mid.gmane.org/20140320150601.GK4405@linux.vnet.ibm.com
>
> Neil
>
>> --
>> 1.7.9.5
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-crypto" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
> --
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>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] drivers/crypto: Use RCU_INIT_POINTER(x, NULL) in nx/nx-842.c
2014-03-23 19:31 Monam Agarwal
@ 2014-03-24 11:16 ` Neil Horman
2014-03-24 12:03 ` Arend van Spriel
0 siblings, 1 reply; 7+ messages in thread
From: Neil Horman @ 2014-03-24 11:16 UTC (permalink / raw)
To: Monam Agarwal
Cc: rcj, mhcerri, fin, herbert, davem, linux-crypto, linux-kernel
On Mon, Mar 24, 2014 at 01:01:04AM +0530, Monam Agarwal wrote:
> This patch replaces rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL)
>
> The rcu_assign_pointer() ensures that the initialization of a structure
> is carried out before storing a pointer to that structure.
> And in the case of the NULL pointer, there is no structure to initialize.
> So, rcu_assign_pointer(p, NULL) can be safely converted to RCU_INIT_POINTER(p, NULL)
>
> Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
> ---
> drivers/crypto/nx/nx-842.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/crypto/nx/nx-842.c b/drivers/crypto/nx/nx-842.c
> index 1e5481d..c4fcbf4 100644
> --- a/drivers/crypto/nx/nx-842.c
> +++ b/drivers/crypto/nx/nx-842.c
> @@ -1234,7 +1234,7 @@ static int __exit nx842_remove(struct vio_dev *viodev)
> old_devdata = rcu_dereference_check(devdata,
> lockdep_is_held(&devdata_mutex));
> of_reconfig_notifier_unregister(&nx842_of_nb);
> - rcu_assign_pointer(devdata, NULL);
> + RCU_INIT_POINTER(devdata, NULL);
> spin_unlock_irqrestore(&devdata_mutex, flags);
> synchronize_rcu();
> dev_set_drvdata(&viodev->dev, NULL);
> @@ -1285,7 +1285,7 @@ static void __exit nx842_exit(void)
> spin_lock_irqsave(&devdata_mutex, flags);
> old_devdata = rcu_dereference_check(devdata,
> lockdep_is_held(&devdata_mutex));
> - rcu_assign_pointer(devdata, NULL);
> + RCU_INIT_POINTER(devdata, NULL);
> spin_unlock_irqrestore(&devdata_mutex, flags);
> synchronize_rcu();
> if (old_devdata)
This really does't seem right. rcu_assign_pointer users ACCESS_ONCE to protect
against multiple loads that allow for concurrent read/write use with parallel
rcu_dereference calls, whereas RCU_INIT_POINTER does not. It also just doesn't
look right. We've already initalized the pointerin nx842_init, we don't need to
re-initalize it here, we need to assign it to NULL.
Neil
> --
> 1.7.9.5
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-crypto" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH] drivers/crypto: Use RCU_INIT_POINTER(x, NULL) in nx/nx-842.c
@ 2014-03-23 19:31 Monam Agarwal
2014-03-24 11:16 ` Neil Horman
0 siblings, 1 reply; 7+ messages in thread
From: Monam Agarwal @ 2014-03-23 19:31 UTC (permalink / raw)
To: rcj, mhcerri, fin, herbert, davem, linux-crypto, linux-kernel
This patch replaces rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL)
The rcu_assign_pointer() ensures that the initialization of a structure
is carried out before storing a pointer to that structure.
And in the case of the NULL pointer, there is no structure to initialize.
So, rcu_assign_pointer(p, NULL) can be safely converted to RCU_INIT_POINTER(p, NULL)
Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
---
drivers/crypto/nx/nx-842.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/crypto/nx/nx-842.c b/drivers/crypto/nx/nx-842.c
index 1e5481d..c4fcbf4 100644
--- a/drivers/crypto/nx/nx-842.c
+++ b/drivers/crypto/nx/nx-842.c
@@ -1234,7 +1234,7 @@ static int __exit nx842_remove(struct vio_dev *viodev)
old_devdata = rcu_dereference_check(devdata,
lockdep_is_held(&devdata_mutex));
of_reconfig_notifier_unregister(&nx842_of_nb);
- rcu_assign_pointer(devdata, NULL);
+ RCU_INIT_POINTER(devdata, NULL);
spin_unlock_irqrestore(&devdata_mutex, flags);
synchronize_rcu();
dev_set_drvdata(&viodev->dev, NULL);
@@ -1285,7 +1285,7 @@ static void __exit nx842_exit(void)
spin_lock_irqsave(&devdata_mutex, flags);
old_devdata = rcu_dereference_check(devdata,
lockdep_is_held(&devdata_mutex));
- rcu_assign_pointer(devdata, NULL);
+ RCU_INIT_POINTER(devdata, NULL);
spin_unlock_irqrestore(&devdata_mutex, flags);
synchronize_rcu();
if (old_devdata)
--
1.7.9.5
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH] drivers/crypto: Use RCU_INIT_POINTER(x, NULL) in nx/nx-842.c
@ 2014-03-22 20:40 Monam Agarwal
0 siblings, 0 replies; 7+ messages in thread
From: Monam Agarwal @ 2014-03-22 20:40 UTC (permalink / raw)
To: rcj, mhcerri, fin, herbert, davem, linux-crypto, linux-kernel
This patch replaces rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL)
The rcu_assign_pointer() ensures that the initialization of a structure
is carried out before storing a pointer to that structure.
And in the case of the NULL pointer, there is no structure to initialize.
So, rcu_assign_pointer(p, NULL) can be safely converted to RCU_INIT_POINTER(p, NULL)
Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
---
drivers/crypto/nx/nx-842.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/crypto/nx/nx-842.c b/drivers/crypto/nx/nx-842.c
index 1e5481d..c4fcbf4 100644
--- a/drivers/crypto/nx/nx-842.c
+++ b/drivers/crypto/nx/nx-842.c
@@ -1234,7 +1234,7 @@ static int __exit nx842_remove(struct vio_dev *viodev)
old_devdata = rcu_dereference_check(devdata,
lockdep_is_held(&devdata_mutex));
of_reconfig_notifier_unregister(&nx842_of_nb);
- rcu_assign_pointer(devdata, NULL);
+ RCU_INIT_POINTER(devdata, NULL);
spin_unlock_irqrestore(&devdata_mutex, flags);
synchronize_rcu();
dev_set_drvdata(&viodev->dev, NULL);
@@ -1285,7 +1285,7 @@ static void __exit nx842_exit(void)
spin_lock_irqsave(&devdata_mutex, flags);
old_devdata = rcu_dereference_check(devdata,
lockdep_is_held(&devdata_mutex));
- rcu_assign_pointer(devdata, NULL);
+ RCU_INIT_POINTER(devdata, NULL);
spin_unlock_irqrestore(&devdata_mutex, flags);
synchronize_rcu();
if (old_devdata)
--
1.7.9.5
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH] drivers/crypto: Use RCU_INIT_POINTER(x, NULL) in nx/nx-842.c
@ 2014-03-22 20:34 Monam Agarwal
0 siblings, 0 replies; 7+ messages in thread
From: Monam Agarwal @ 2014-03-22 20:34 UTC (permalink / raw)
To: rcj, mhcerri, fin, herbert, davem, linux-crypto, linux-kernel
This patch replaces rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL)
The rcu_assign_pointer() ensures that the initialization of a structure
is carried out before storing a pointer to that structure.
And in the case of the NULL pointer, there is no structure to initialize.
So, rcu_assign_pointer(p, NULL) can be safely converted to RCU_INIT_POINTER(p, NULL)
Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
---
drivers/crypto/nx/nx-842.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/crypto/nx/nx-842.c b/drivers/crypto/nx/nx-842.c
index 1e5481d..c4fcbf4 100644
--- a/drivers/crypto/nx/nx-842.c
+++ b/drivers/crypto/nx/nx-842.c
@@ -1234,7 +1234,7 @@ static int __exit nx842_remove(struct vio_dev *viodev)
old_devdata = rcu_dereference_check(devdata,
lockdep_is_held(&devdata_mutex));
of_reconfig_notifier_unregister(&nx842_of_nb);
- rcu_assign_pointer(devdata, NULL);
+ RCU_INIT_POINTER(devdata, NULL);
spin_unlock_irqrestore(&devdata_mutex, flags);
synchronize_rcu();
dev_set_drvdata(&viodev->dev, NULL);
@@ -1285,7 +1285,7 @@ static void __exit nx842_exit(void)
spin_lock_irqsave(&devdata_mutex, flags);
old_devdata = rcu_dereference_check(devdata,
lockdep_is_held(&devdata_mutex));
- rcu_assign_pointer(devdata, NULL);
+ RCU_INIT_POINTER(devdata, NULL);
spin_unlock_irqrestore(&devdata_mutex, flags);
synchronize_rcu();
if (old_devdata)
--
1.7.9.5
^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2014-04-16 13:48 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-03-23 19:32 [PATCH] drivers/crypto: Use RCU_INIT_POINTER(x, NULL) in nx/nx-842.c Monam Agarwal
2014-04-16 13:48 ` Herbert Xu
-- strict thread matches above, loose matches on Subject: below --
2014-03-23 19:31 Monam Agarwal
2014-03-24 11:16 ` Neil Horman
2014-03-24 12:03 ` Arend van Spriel
2014-03-22 20:40 Monam Agarwal
2014-03-22 20:34 Monam Agarwal
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