[PATCH] libnvdimm: remove redundant assignment to pointer 'dev'

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* [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
@ 2018-02-05 14:08 ` Colin King
  0 siblings, 0 replies; 15+ messages in thread
From: Colin King @ 2018-02-05 14:08 UTC (permalink / raw)
  To: Dan Williams, linux-nvdimm; +Cc: kernel-janitors, linux-kernel

From: Colin Ian King <colin.king@canonical.com>

Pointer dev is being assigned a value that is never read, it is being
re-assigned the same value later on, hence the initialization is redundant
and can be removed.

Cleans up clang warning:
drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
its initialization is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/nvdimm/pfn_devs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index f5c4e8c6e29d..2f4d18752c97 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -304,7 +304,7 @@ static const struct attribute_group *nd_pfn_attribute_groups[] = {
 struct device *nd_pfn_devinit(struct nd_pfn *nd_pfn,
 		struct nd_namespace_common *ndns)
 {
-	struct device *dev = &nd_pfn->dev;
+	struct device *dev;
 
 	if (!nd_pfn)
 		return NULL;
-- 
2.15.1


^ permalink raw reply related	[flat|nested] 15+ messages in thread

* [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
@ 2018-02-05 14:08 ` Colin King
  0 siblings, 0 replies; 15+ messages in thread
From: Colin King @ 2018-02-05 14:08 UTC (permalink / raw)
  To: Dan Williams, linux-nvdimm; +Cc: kernel-janitors, linux-kernel

From: Colin Ian King <colin.king@canonical.com>

Pointer dev is being assigned a value that is never read, it is being
re-assigned the same value later on, hence the initialization is redundant
and can be removed.

Cleans up clang warning:
drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
its initialization is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/nvdimm/pfn_devs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index f5c4e8c6e29d..2f4d18752c97 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -304,7 +304,7 @@ static const struct attribute_group *nd_pfn_attribute_groups[] = {
 struct device *nd_pfn_devinit(struct nd_pfn *nd_pfn,
 		struct nd_namespace_common *ndns)
 {
-	struct device *dev = &nd_pfn->dev;
+	struct device *dev;
 
 	if (!nd_pfn)
 		return NULL;
-- 
2.15.1

^ permalink raw reply related	[flat|nested] 15+ messages in thread

* [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
@ 2018-02-05 14:08 ` Colin King
  0 siblings, 0 replies; 15+ messages in thread
From: Colin King @ 2018-02-05 14:08 UTC (permalink / raw)
  To: Dan Williams, linux-nvdimm; +Cc: kernel-janitors, linux-kernel

From: Colin Ian King <colin.king@canonical.com>

Pointer dev is being assigned a value that is never read, it is being
re-assigned the same value later on, hence the initialization is redundant
and can be removed.

Cleans up clang warning:
drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
its initialization is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/nvdimm/pfn_devs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index f5c4e8c6e29d..2f4d18752c97 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -304,7 +304,7 @@ static const struct attribute_group *nd_pfn_attribute_groups[] = {
 struct device *nd_pfn_devinit(struct nd_pfn *nd_pfn,
 		struct nd_namespace_common *ndns)
 {
-	struct device *dev = &nd_pfn->dev;
+	struct device *dev;
 
 	if (!nd_pfn)
 		return NULL;
-- 
2.15.1

_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm

^ permalink raw reply related	[flat|nested] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
  2018-02-05 14:08 ` Colin King
  (?)
@ 2018-02-05 18:20   ` Ross Zwisler
  -1 siblings, 0 replies; 15+ messages in thread
From: Ross Zwisler @ 2018-02-05 18:20 UTC (permalink / raw)
  To: Colin King; +Cc: kernel-janitors, linux-kernel, linux-nvdimm

On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Pointer dev is being assigned a value that is never read, it is being
> re-assigned the same value later on, hence the initialization is redundant
> and can be removed.
> 
> Cleans up clang warning:
> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
> its initialization is never read
> 
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>

More importantly this fixes a potential NULL pointer dereference.  nd_pfn
is checked for NULL a few lines down, but we would have crashed here trying to
get nd_pfn->dev.

We can append the above info to the changelog when we apply.

> ---
>  drivers/nvdimm/pfn_devs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
> index f5c4e8c6e29d..2f4d18752c97 100644
> --- a/drivers/nvdimm/pfn_devs.c
> +++ b/drivers/nvdimm/pfn_devs.c
> @@ -304,7 +304,7 @@ static const struct attribute_group *nd_pfn_attribute_groups[] = {
>  struct device *nd_pfn_devinit(struct nd_pfn *nd_pfn,
>  		struct nd_namespace_common *ndns)
>  {
> -	struct device *dev = &nd_pfn->dev;
> +	struct device *dev;
>  
>  	if (!nd_pfn)
>  		return NULL;
> -- 
> 2.15.1
> 
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
@ 2018-02-05 18:20   ` Ross Zwisler
  0 siblings, 0 replies; 15+ messages in thread
From: Ross Zwisler @ 2018-02-05 18:20 UTC (permalink / raw)
  To: Colin King; +Cc: Dan Williams, linux-nvdimm, kernel-janitors, linux-kernel

On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Pointer dev is being assigned a value that is never read, it is being
> re-assigned the same value later on, hence the initialization is redundant
> and can be removed.
> 
> Cleans up clang warning:
> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
> its initialization is never read
> 
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>

More importantly this fixes a potential NULL pointer dereference.  nd_pfn
is checked for NULL a few lines down, but we would have crashed here trying to
get nd_pfn->dev.

We can append the above info to the changelog when we apply.

> ---
>  drivers/nvdimm/pfn_devs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
> index f5c4e8c6e29d..2f4d18752c97 100644
> --- a/drivers/nvdimm/pfn_devs.c
> +++ b/drivers/nvdimm/pfn_devs.c
> @@ -304,7 +304,7 @@ static const struct attribute_group *nd_pfn_attribute_groups[] = {
>  struct device *nd_pfn_devinit(struct nd_pfn *nd_pfn,
>  		struct nd_namespace_common *ndns)
>  {
> -	struct device *dev = &nd_pfn->dev;
> +	struct device *dev;
>  
>  	if (!nd_pfn)
>  		return NULL;
> -- 
> 2.15.1
> 
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
@ 2018-02-05 18:20   ` Ross Zwisler
  0 siblings, 0 replies; 15+ messages in thread
From: Ross Zwisler @ 2018-02-05 18:20 UTC (permalink / raw)
  To: Colin King; +Cc: kernel-janitors, linux-kernel, linux-nvdimm

On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Pointer dev is being assigned a value that is never read, it is being
> re-assigned the same value later on, hence the initialization is redundant
> and can be removed.
> 
> Cleans up clang warning:
> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
> its initialization is never read
> 
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>

More importantly this fixes a potential NULL pointer dereference.  nd_pfn
is checked for NULL a few lines down, but we would have crashed here trying to
get nd_pfn->dev.

We can append the above info to the changelog when we apply.

> ---
>  drivers/nvdimm/pfn_devs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
> index f5c4e8c6e29d..2f4d18752c97 100644
> --- a/drivers/nvdimm/pfn_devs.c
> +++ b/drivers/nvdimm/pfn_devs.c
> @@ -304,7 +304,7 @@ static const struct attribute_group *nd_pfn_attribute_groups[] = {
>  struct device *nd_pfn_devinit(struct nd_pfn *nd_pfn,
>  		struct nd_namespace_common *ndns)
>  {
> -	struct device *dev = &nd_pfn->dev;
> +	struct device *dev;
>  
>  	if (!nd_pfn)
>  		return NULL;
> -- 
> 2.15.1
> 
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm
_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
  2018-02-05 18:20   ` Ross Zwisler
  (?)
@ 2018-02-05 18:44     ` Dan Williams
  -1 siblings, 0 replies; 15+ messages in thread
From: Dan Williams @ 2018-02-05 18:44 UTC (permalink / raw)
  To: Ross Zwisler
  Cc: Colin King, kernel-janitors, Linux Kernel Mailing List,
	linux-nvdimm

On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler
<ross.zwisler@linux.intel.com> wrote:
> On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> Pointer dev is being assigned a value that is never read, it is being
>> re-assigned the same value later on, hence the initialization is redundant
>> and can be removed.
>>
>> Cleans up clang warning:
>> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
>> its initialization is never read
>>
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>
> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
>
> More importantly this fixes a potential NULL pointer dereference.  nd_pfn
> is checked for NULL a few lines down, but we would have crashed here trying to
> get nd_pfn->dev.
>

No we wouldn't crash. We're just calculating the address, not
de-referencing a NULL pointer.

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
@ 2018-02-05 18:44     ` Dan Williams
  0 siblings, 0 replies; 15+ messages in thread
From: Dan Williams @ 2018-02-05 18:44 UTC (permalink / raw)
  To: Ross Zwisler
  Cc: Colin King, linux-nvdimm, kernel-janitors,
	Linux Kernel Mailing List

On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler
<ross.zwisler@linux.intel.com> wrote:
> On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> Pointer dev is being assigned a value that is never read, it is being
>> re-assigned the same value later on, hence the initialization is redundant
>> and can be removed.
>>
>> Cleans up clang warning:
>> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
>> its initialization is never read
>>
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>
> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
>
> More importantly this fixes a potential NULL pointer dereference.  nd_pfn
> is checked for NULL a few lines down, but we would have crashed here trying to
> get nd_pfn->dev.
>

No we wouldn't crash. We're just calculating the address, not
de-referencing a NULL pointer.

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
@ 2018-02-05 18:44     ` Dan Williams
  0 siblings, 0 replies; 15+ messages in thread
From: Dan Williams @ 2018-02-05 18:44 UTC (permalink / raw)
  To: Ross Zwisler
  Cc: Colin King, kernel-janitors, Linux Kernel Mailing List,
	linux-nvdimm

On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler
<ross.zwisler@linux.intel.com> wrote:
> On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> Pointer dev is being assigned a value that is never read, it is being
>> re-assigned the same value later on, hence the initialization is redundant
>> and can be removed.
>>
>> Cleans up clang warning:
>> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
>> its initialization is never read
>>
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>
> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
>
> More importantly this fixes a potential NULL pointer dereference.  nd_pfn
> is checked for NULL a few lines down, but we would have crashed here trying to
> get nd_pfn->dev.
>

No we wouldn't crash. We're just calculating the address, not
de-referencing a NULL pointer.
_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
  2018-02-05 18:44     ` Dan Williams
  (?)
@ 2018-02-05 20:46       ` Colin Ian King
  -1 siblings, 0 replies; 15+ messages in thread
From: Colin Ian King @ 2018-02-05 20:46 UTC (permalink / raw)
  To: Dan Williams, Ross Zwisler
  Cc: kernel-janitors, Linux Kernel Mailing List, linux-nvdimm

On 05/02/18 18:44, Dan Williams wrote:
> On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler
> <ross.zwisler@linux.intel.com> wrote:
>> On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
>>> From: Colin Ian King <colin.king@canonical.com>
>>>
>>> Pointer dev is being assigned a value that is never read, it is being
>>> re-assigned the same value later on, hence the initialization is redundant
>>> and can be removed.
>>>
>>> Cleans up clang warning:
>>> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
>>> its initialization is never read
>>>
>>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>>
>> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
>>
>> More importantly this fixes a potential NULL pointer dereference.  nd_pfn
>> is checked for NULL a few lines down, but we would have crashed here trying to
>> get nd_pfn->dev.
>>
> 
> No we wouldn't crash. We're just calculating the address, not
> de-referencing a NULL pointer.

Indeed, it's just a warning clean up. Nothing more.

> --
> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" 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] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
@ 2018-02-05 20:46       ` Colin Ian King
  0 siblings, 0 replies; 15+ messages in thread
From: Colin Ian King @ 2018-02-05 20:46 UTC (permalink / raw)
  To: Dan Williams, Ross Zwisler
  Cc: linux-nvdimm, kernel-janitors, Linux Kernel Mailing List

On 05/02/18 18:44, Dan Williams wrote:
> On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler
> <ross.zwisler@linux.intel.com> wrote:
>> On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
>>> From: Colin Ian King <colin.king@canonical.com>
>>>
>>> Pointer dev is being assigned a value that is never read, it is being
>>> re-assigned the same value later on, hence the initialization is redundant
>>> and can be removed.
>>>
>>> Cleans up clang warning:
>>> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
>>> its initialization is never read
>>>
>>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>>
>> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
>>
>> More importantly this fixes a potential NULL pointer dereference.  nd_pfn
>> is checked for NULL a few lines down, but we would have crashed here trying to
>> get nd_pfn->dev.
>>
> 
> No we wouldn't crash. We're just calculating the address, not
> de-referencing a NULL pointer.

Indeed, it's just a warning clean up. Nothing more.

> --
> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" 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] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
@ 2018-02-05 20:46       ` Colin Ian King
  0 siblings, 0 replies; 15+ messages in thread
From: Colin Ian King @ 2018-02-05 20:46 UTC (permalink / raw)
  To: Dan Williams, Ross Zwisler
  Cc: kernel-janitors, Linux Kernel Mailing List, linux-nvdimm

On 05/02/18 18:44, Dan Williams wrote:
> On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler
> <ross.zwisler@linux.intel.com> wrote:
>> On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
>>> From: Colin Ian King <colin.king@canonical.com>
>>>
>>> Pointer dev is being assigned a value that is never read, it is being
>>> re-assigned the same value later on, hence the initialization is redundant
>>> and can be removed.
>>>
>>> Cleans up clang warning:
>>> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
>>> its initialization is never read
>>>
>>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>>
>> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
>>
>> More importantly this fixes a potential NULL pointer dereference.  nd_pfn
>> is checked for NULL a few lines down, but we would have crashed here trying to
>> get nd_pfn->dev.
>>
> 
> No we wouldn't crash. We're just calculating the address, not
> de-referencing a NULL pointer.

Indeed, it's just a warning clean up. Nothing more.

> --
> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
  2018-02-05 18:44     ` Dan Williams
  (?)
@ 2018-02-05 21:35       ` Ross Zwisler
  -1 siblings, 0 replies; 15+ messages in thread
From: Ross Zwisler @ 2018-02-05 21:35 UTC (permalink / raw)
  To: Dan Williams
  Cc: Colin King, kernel-janitors, Linux Kernel Mailing List,
	linux-nvdimm

On Mon, Feb 05, 2018 at 10:44:07AM -0800, Dan Williams wrote:
> On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler
> <ross.zwisler@linux.intel.com> wrote:
> > On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
> >> From: Colin Ian King <colin.king@canonical.com>
> >>
> >> Pointer dev is being assigned a value that is never read, it is being
> >> re-assigned the same value later on, hence the initialization is redundant
> >> and can be removed.
> >>
> >> Cleans up clang warning:
> >> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
> >> its initialization is never read
> >>
> >> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> >
> > Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> >
> > More importantly this fixes a potential NULL pointer dereference.  nd_pfn
> > is checked for NULL a few lines down, but we would have crashed here trying to
> > get nd_pfn->dev.
> >
> 
> No we wouldn't crash. We're just calculating the address, not
> de-referencing a NULL pointer.

Ah, yep, you're right of course.  This is exactly how offsetof() is
implemented in some architectures.  Thanks.

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
@ 2018-02-05 21:35       ` Ross Zwisler
  0 siblings, 0 replies; 15+ messages in thread
From: Ross Zwisler @ 2018-02-05 21:35 UTC (permalink / raw)
  To: Dan Williams
  Cc: Ross Zwisler, Colin King, linux-nvdimm, kernel-janitors,
	Linux Kernel Mailing List

On Mon, Feb 05, 2018 at 10:44:07AM -0800, Dan Williams wrote:
> On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler
> <ross.zwisler@linux.intel.com> wrote:
> > On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
> >> From: Colin Ian King <colin.king@canonical.com>
> >>
> >> Pointer dev is being assigned a value that is never read, it is being
> >> re-assigned the same value later on, hence the initialization is redundant
> >> and can be removed.
> >>
> >> Cleans up clang warning:
> >> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
> >> its initialization is never read
> >>
> >> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> >
> > Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> >
> > More importantly this fixes a potential NULL pointer dereference.  nd_pfn
> > is checked for NULL a few lines down, but we would have crashed here trying to
> > get nd_pfn->dev.
> >
> 
> No we wouldn't crash. We're just calculating the address, not
> de-referencing a NULL pointer.

Ah, yep, you're right of course.  This is exactly how offsetof() is
implemented in some architectures.  Thanks.

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH] libnvdimm: remove redundant assignment to pointer 'dev'
@ 2018-02-05 21:35       ` Ross Zwisler
  0 siblings, 0 replies; 15+ messages in thread
From: Ross Zwisler @ 2018-02-05 21:35 UTC (permalink / raw)
  To: Dan Williams
  Cc: Colin King, kernel-janitors, Linux Kernel Mailing List,
	linux-nvdimm

On Mon, Feb 05, 2018 at 10:44:07AM -0800, Dan Williams wrote:
> On Mon, Feb 5, 2018 at 10:20 AM, Ross Zwisler
> <ross.zwisler@linux.intel.com> wrote:
> > On Mon, Feb 05, 2018 at 02:08:52PM +0000, Colin King wrote:
> >> From: Colin Ian King <colin.king@canonical.com>
> >>
> >> Pointer dev is being assigned a value that is never read, it is being
> >> re-assigned the same value later on, hence the initialization is redundant
> >> and can be removed.
> >>
> >> Cleans up clang warning:
> >> drivers/nvdimm/pfn_devs.c:307:17: warning: Value stored to 'dev' during
> >> its initialization is never read
> >>
> >> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> >
> > Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> >
> > More importantly this fixes a potential NULL pointer dereference.  nd_pfn
> > is checked for NULL a few lines down, but we would have crashed here trying to
> > get nd_pfn->dev.
> >
> 
> No we wouldn't crash. We're just calculating the address, not
> de-referencing a NULL pointer.

Ah, yep, you're right of course.  This is exactly how offsetof() is
implemented in some architectures.  Thanks.
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^ permalink raw reply	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2018-02-05 21:36 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-02-05 14:08 [PATCH] libnvdimm: remove redundant assignment to pointer 'dev' Colin King
2018-02-05 14:08 ` Colin King
2018-02-05 14:08 ` Colin King
2018-02-05 18:20 ` Ross Zwisler
2018-02-05 18:20   ` Ross Zwisler
2018-02-05 18:20   ` Ross Zwisler
2018-02-05 18:44   ` Dan Williams
2018-02-05 18:44     ` Dan Williams
2018-02-05 18:44     ` Dan Williams
2018-02-05 20:46     ` Colin Ian King
2018-02-05 20:46       ` Colin Ian King
2018-02-05 20:46       ` Colin Ian King
2018-02-05 21:35     ` Ross Zwisler
2018-02-05 21:35       ` Ross Zwisler
2018-02-05 21:35       ` Ross Zwisler

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