[PATCH] usb: dwc3: free dwc->regset on dwc3_debugfs_exit

[PATCH] usb: dwc3: free dwc->regset on dwc3_debugfs_exit

[changbin.du]

From: "Du, Changbin" <changbin.du@intel.com>

dwc->regset is allocated on dwc3_debugfs_init, and should
be released on dwc3_debugfs_exit.

Signed-off-by: Du, Changbin <changbin.du@intel.com>
---
This patch is seperated from patch set:
 [PATCH v2 0/3] Improvement, fix and new entry for dwc3 debugfs
Because it is not related to other 2 patches.

---
 drivers/usb/dwc3/debugfs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
index 9ac37fe..9eeb444 100644
--- a/drivers/usb/dwc3/debugfs.c
+++ b/drivers/usb/dwc3/debugfs.c
@@ -687,4 +687,7 @@ void dwc3_debugfs_exit(struct dwc3 *dwc)
 {
 	debugfs_remove_recursive(dwc->root);
 	dwc->root = NULL;
+
+	kfree(dwc->regset);
+	dwc->regset = NULL;
 }
-- 
2.5.0

Re: [PATCH] usb: dwc3: free dwc->regset on dwc3_debugfs_exit

[Felipe Balbi]

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changbin.du@intel.com writes:
> From: "Du, Changbin" <changbin.du@intel.com>
>
> dwc->regset is allocated on dwc3_debugfs_init, and should
> be released on dwc3_debugfs_exit.
>
> Signed-off-by: Du, Changbin <changbin.du@intel.com>
> ---
> This patch is seperated from patch set:
>  [PATCH v2 0/3] Improvement, fix and new entry for dwc3 debugfs
> Because it is not related to other 2 patches.
>
> ---
>  drivers/usb/dwc3/debugfs.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
> index 9ac37fe..9eeb444 100644
> --- a/drivers/usb/dwc3/debugfs.c
> +++ b/drivers/usb/dwc3/debugfs.c
> @@ -687,4 +687,7 @@ void dwc3_debugfs_exit(struct dwc3 *dwc)
>  {
>  	debugfs_remove_recursive(dwc->root);
>  	dwc->root = NULL;
> +
> +	kfree(dwc->regset);

we also need a kfree() on dwc3_debugfs_init().

> +	dwc->regset = NULL;

setting regset to NULL is unnecessary. We only call dwc3_debugfs_exit()
when removing the driver.

-- 
balbi

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RE: [PATCH] usb: dwc3: free dwc->regset on dwc3_debugfs_exit

[Du, Changbin]

> > diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
> > index 9ac37fe..9eeb444 100644
> > --- a/drivers/usb/dwc3/debugfs.c
> > +++ b/drivers/usb/dwc3/debugfs.c
> > @@ -687,4 +687,7 @@ void dwc3_debugfs_exit(struct dwc3 *dwc)
> >  {
> >  	debugfs_remove_recursive(dwc->root);
> >  	dwc->root = NULL;
> > +
> > +	kfree(dwc->regset);
> 
> we also need a kfree() on dwc3_debugfs_init().
This patch is based on the patch set 
[PATCH v3 1/2] usb: dwc3: make dwc3_debugfs_init return value be void> 
So, they do has dependency. :)

> > +	dwc->regset = NULL;
> 
> setting regset to NULL is unnecessary. We only call dwc3_debugfs_exit()
> when removing the driver.
> 
> --
> Balbi
I'd like keep this line even it is unnecessary, because It is a good habit to
Avoid wild pointers. Just like the dwc->root = NULL.

Thanks,
Du, Changbin

RE: [PATCH] usb: dwc3: free dwc->regset on dwc3_debugfs_exit

[Felipe Balbi]

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"Du, Changbin" <changbin.du@intel.com> writes:

>> > diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
>> > index 9ac37fe..9eeb444 100644
>> > --- a/drivers/usb/dwc3/debugfs.c
>> > +++ b/drivers/usb/dwc3/debugfs.c
>> > @@ -687,4 +687,7 @@ void dwc3_debugfs_exit(struct dwc3 *dwc)
>> >  {
>> >  	debugfs_remove_recursive(dwc->root);
>> >  	dwc->root = NULL;
>> > +
>> > +	kfree(dwc->regset);
>> 
>> we also need a kfree() on dwc3_debugfs_init().
> This patch is based on the patch set 
> [PATCH v3 1/2] usb: dwc3: make dwc3_debugfs_init return value be void> 
> So, they do has dependency. :)

I _did_ mention on previous set that fixes and new-features shouldn't
have dependencies between them. That was the whole point of splitting
the series in two.

>> > +	dwc->regset = NULL;
>> 
>> setting regset to NULL is unnecessary. We only call dwc3_debugfs_exit()
>> when removing the driver.
>> 
>> --
>> Balbi
> I'd like keep this line even it is unnecessary, because It is a good habit to
> Avoid wild pointers. Just like the dwc->root = NULL.

there won't be any wild pointers here, we'll free struct dwc3 *dwc itself.

-- 
balbi

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RE: [PATCH] usb: dwc3: free dwc->regset on dwc3_debugfs_exit

[Du, Changbin]

> 
> >> > +	dwc->regset = NULL;
> >>
> >> setting regset to NULL is unnecessary. We only call dwc3_debugfs_exit()
> >> when removing the driver.
> >>
> >> --
> >> Balbi
> > I'd like keep this line even it is unnecessary, because It is a good habit to
> > Avoid wild pointers. Just like the dwc->root = NULL.
> 
> there won't be any wild pointers here, we'll free struct dwc3 *dwc itself.
> 
> --
> Balbi
I agree the dwc will be freed in current code. But the 'free' logical is out
of the debugfs code. They should be treat as some logical independent. Per
this point, I still think set pointer to null is not bad. For example, if dwc3 core
code invoke dwc3_debugfs_exit twice by mistake(just an example case, not
really), then no crash/impact for the second call.

Thanks,
Du, Changbin

RE: [PATCH] usb: dwc3: free dwc->regset on dwc3_debugfs_exit

[Felipe Balbi]

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Hi,

"Du, Changbin" <changbin.du@intel.com> writes:
>> 
>> >> > +	dwc->regset = NULL;
>> >>
>> >> setting regset to NULL is unnecessary. We only call dwc3_debugfs_exit()
>> >> when removing the driver.
>> >>
>> >> --
>> >> Balbi
>> > I'd like keep this line even it is unnecessary, because It is a good habit to
>> > Avoid wild pointers. Just like the dwc->root = NULL.
>> 
>> there won't be any wild pointers here, we'll free struct dwc3 *dwc itself.
>> 
>> --
>> Balbi
> I agree the dwc will be freed in current code. But the 'free' logical is out
> of the debugfs code. They should be treat as some logical independent. Per
> this point, I still think set pointer to null is not bad. For example, if dwc3 core
> code invoke dwc3_debugfs_exit twice by mistake(just an example case, not
> really), then no crash/impact for the second call.

the second call should crash because it's clearly wrong ;-) If dwc3 ever
calls dwc3_debugfs_exit() twice, it really deserves to crash. It's
something so wrong that we want the verbosity and urgency of a kernel
oops to make sure we fix it ASAP.

If, however, we set it to null, it might be years before we notice
anything's wrong.

-- 
balbi

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RE: [PATCH] usb: dwc3: free dwc->regset on dwc3_debugfs_exit

[Du, Changbin]

> Hi,
> 
> "Du, Changbin" <changbin.du@intel.com> writes:
> >>
> >> >> > +	dwc->regset = NULL;
> >> >>
> >> >> setting regset to NULL is unnecessary. We only call
> dwc3_debugfs_exit()
> >> >> when removing the driver.
> >> >>
> >> >> --
> >> >> Balbi
> >> > I'd like keep this line even it is unnecessary, because It is a good habit to
> >> > Avoid wild pointers. Just like the dwc->root = NULL.
> >>
> >> there won't be any wild pointers here, we'll free struct dwc3 *dwc itself.
> >>
> >> --
> >> Balbi
> > I agree the dwc will be freed in current code. But the 'free' logical is out
> > of the debugfs code. They should be treat as some logical independent.
> Per
> > this point, I still think set pointer to null is not bad. For example, if dwc3
> core
> > code invoke dwc3_debugfs_exit twice by mistake(just an example case,
> not
> > really), then no crash/impact for the second call.
> 
> the second call should crash because it's clearly wrong ;-) If dwc3 ever
> calls dwc3_debugfs_exit() twice, it really deserves to crash. It's
> something so wrong that we want the verbosity and urgency of a kernel
> oops to make sure we fix it ASAP.
> 
> If, however, we set it to null, it might be years before we notice
> anything's wrong.
> 
> --
> Balbi

Hmm, I agree from this point. I will combine this patch with other two patches
(due to their dependency). And I'd like remove the 'dwc->root=NULL' as well,
Is it ok for you?

Thx,
Du, Changbin
 

RE: [PATCH] usb: dwc3: free dwc->regset on dwc3_debugfs_exit

[Felipe Balbi]

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Hi Changbin,

"Du, Changbin" <changbin.du@intel.com> writes:
>> Hi,
>> 
>> "Du, Changbin" <changbin.du@intel.com> writes:
>> >>
>> >> >> > +	dwc->regset = NULL;
>> >> >>
>> >> >> setting regset to NULL is unnecessary. We only call
>> dwc3_debugfs_exit()
>> >> >> when removing the driver.
>> >> >>
>> >> >> --
>> >> >> Balbi
>> >> > I'd like keep this line even it is unnecessary, because It is a good habit to
>> >> > Avoid wild pointers. Just like the dwc->root = NULL.
>> >>
>> >> there won't be any wild pointers here, we'll free struct dwc3 *dwc itself.
>> >>
>> >> --
>> >> Balbi
>> > I agree the dwc will be freed in current code. But the 'free' logical is out
>> > of the debugfs code. They should be treat as some logical independent.
>> Per
>> > this point, I still think set pointer to null is not bad. For example, if dwc3
>> core
>> > code invoke dwc3_debugfs_exit twice by mistake(just an example case,
>> not
>> > really), then no crash/impact for the second call.
>> 
>> the second call should crash because it's clearly wrong ;-) If dwc3 ever
>> calls dwc3_debugfs_exit() twice, it really deserves to crash. It's
>> something so wrong that we want the verbosity and urgency of a kernel
>> oops to make sure we fix it ASAP.
>> 
>> If, however, we set it to null, it might be years before we notice
>> anything's wrong.
>> 
>> --
>> Balbi
>
> Hmm, I agree from this point. I will combine this patch with other two patches
> (due to their dependency). And I'd like remove the 'dwc->root=NULL' as well,

you are creating a dependency that doesn't exist. Please stop that. You
should have two separate branches based on v4.6-rc3 (or, if you prefer,
one based on my testing/fixes and another based on my testing/next). On
one branch you have *only* $subject and you fix *all* the memory
leaks. On the other branch you have the other two patches.

Ignore the fact that we might have a conflict, that's for git (and
maintainers) to handle when they happen.

Again, don't create dependencies between fixes for the -rc cycle and
changes for the next merge window.

> Is it ok for you?

yeah, please remove root = NULL as that's completely unnecessary, but
split these patches in separate branches and fix all memory leaks.

-- 
balbi

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RE: [PATCH] usb: dwc3: free dwc->regset on dwc3_debugfs_exit

[Du, Changbin]

Hi, Balbi,

> > Hmm, I agree from this point. I will combine this patch with other two
> patches
> > (due to their dependency). And I'd like remove the 'dwc->root=NULL' as
> well,
> 
> you are creating a dependency that doesn't exist. Please stop that. You
> should have two separate branches based on v4.6-rc3 (or, if you prefer,
> one based on my testing/fixes and another based on my testing/next). On
> one branch you have *only* $subject and you fix *all* the memory
> leaks. On the other branch you have the other two patches.
> 
> Ignore the fact that we might have a conflict, that's for git (and
> maintainers) to handle when they happen.
> 
> Again, don't create dependencies between fixes for the -rc cycle and
> changes for the next merge window.
> 
Thanks for dedicated explanation. I was concern about the conflict.
Now it is very clear for me to handle such situation.

> > Is it ok for you?
> 
> yeah, please remove root = NULL as that's completely unnecessary, but
> split these patches in separate branches and fix all memory leaks.
> 
> --
> balbi

RE: [PATCH] usb: dwc3: free dwc->regset on dwc3_debugfs_exit

[Felipe Balbi]

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Hi,

"Du, Changbin" <changbin.du@intel.com> writes:
> Hi, Balbi,
>
>> > Hmm, I agree from this point. I will combine this patch with other two
>> patches
>> > (due to their dependency). And I'd like remove the 'dwc->root=NULL' as
>> well,
>> 
>> you are creating a dependency that doesn't exist. Please stop that. You
>> should have two separate branches based on v4.6-rc3 (or, if you prefer,
>> one based on my testing/fixes and another based on my testing/next). On
>> one branch you have *only* $subject and you fix *all* the memory
>> leaks. On the other branch you have the other two patches.
>> 
>> Ignore the fact that we might have a conflict, that's for git (and
>> maintainers) to handle when they happen.
>> 
>> Again, don't create dependencies between fixes for the -rc cycle and
>> changes for the next merge window.
>> 
> Thanks for dedicated explanation. I was concern about the conflict.

yeah, no problem ;-)

> Now it is very clear for me to handle such situation.

good :-) glad we could sort it out.

-- 
balbi

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[PATCH v2] usb: dwc3: fix memory leak of dwc->regset

[changbin.du]

From: "Du, Changbin" <changbin.du@intel.com>

dwc->regset is allocated on dwc3_debugfs_init, and should
be released on init failure or dwc3_debugfs_exit. Btw,
The line "dwc->root = NULL" is unnecessary, so remove it.

Signed-off-by: Du, Changbin <changbin.du@intel.com>
---
v2:
  Title changed;
  free dwc->regset on failure path.

---
 drivers/usb/dwc3/debugfs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
index 9ac37fe..abd8889 100644
--- a/drivers/usb/dwc3/debugfs.c
+++ b/drivers/usb/dwc3/debugfs.c
@@ -678,7 +678,8 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 
 err1:
 	debugfs_remove_recursive(root);
-
+	if (!dwc->regset)
+		kfree(dwc->regset);
 err0:
 	return ret;
 }
@@ -686,5 +687,5 @@ err0:
 void dwc3_debugfs_exit(struct dwc3 *dwc)
 {
 	debugfs_remove_recursive(dwc->root);
-	dwc->root = NULL;
+	kfree(dwc->regset);
 }
-- 
2.5.0

[PATCH v3] usb: dwc3: fix memory leak of dwc->regset

[changbin.du]

From: "Du, Changbin" <changbin.du@intel.com>

dwc->regset is allocated on dwc3_debugfs_init, and should
be released on init failure or dwc3_debugfs_exit. Btw,
The line "dwc->root = NULL" is unnecessary, so remove it.

Signed-off-by: Du, Changbin <changbin.du@intel.com>
---
v3:
  remove unnecessary if(!NULL) for free
v2:
  Title changed;
  free dwc->regset on failure path.
---
 drivers/usb/dwc3/debugfs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
index 9ac37fe..07d99eb 100644
--- a/drivers/usb/dwc3/debugfs.c
+++ b/drivers/usb/dwc3/debugfs.c
@@ -678,7 +678,7 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 
 err1:
 	debugfs_remove_recursive(root);
-
+	kfree(dwc->regset);
 err0:
 	return ret;
 }
@@ -686,5 +686,5 @@ err0:
 void dwc3_debugfs_exit(struct dwc3 *dwc)
 {
 	debugfs_remove_recursive(dwc->root);
-	dwc->root = NULL;
+	kfree(dwc->regset);
 }
-- 
2.5.0

Re: [PATCH v2] usb: dwc3: fix memory leak of dwc->regset

[Felipe Balbi]

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Hi,

changbin.du@intel.com writes:
> From: "Du, Changbin" <changbin.du@intel.com>
>
> dwc->regset is allocated on dwc3_debugfs_init, and should
> be released on init failure or dwc3_debugfs_exit. Btw,
> The line "dwc->root = NULL" is unnecessary, so remove it.
>
> Signed-off-by: Du, Changbin <changbin.du@intel.com>
> ---
> v2:
>   Title changed;
>   free dwc->regset on failure path.
>
> ---
>  drivers/usb/dwc3/debugfs.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
> index 9ac37fe..abd8889 100644
> --- a/drivers/usb/dwc3/debugfs.c
> +++ b/drivers/usb/dwc3/debugfs.c
> @@ -678,7 +678,8 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
>  
>  err1:
>  	debugfs_remove_recursive(root);
> -
> +	if (!dwc->regset)
> +		kfree(dwc->regset);

IOW:

        if regset is NULL, free NULL.

This check is wrong and unnecessary ;-) kfree(NULL) is safe.

-- 
balbi

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Re: [PATCH v3] usb: dwc3: fix memory leak of dwc->regset

[Felipe Balbi]

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Hi,

changbin.du@intel.com writes:
> From: "Du, Changbin" <changbin.du@intel.com>
>
> dwc->regset is allocated on dwc3_debugfs_init, and should
> be released on init failure or dwc3_debugfs_exit. Btw,
> The line "dwc->root = NULL" is unnecessary, so remove it.
>
> Signed-off-by: Du, Changbin <changbin.du@intel.com>
> ---

I've modifed the patch a little bit just to make sure the error labels
are easy to follow:

commit c7232c5fdcc5e1b6fc39b498b58573553ebb43da
Author: Du, Changbin <changbin.du@intel.com>
Date:   Tue Apr 12 16:24:34 2016 +0800

    usb: dwc3: fix memory leak of dwc->regset
    
    dwc->regset is allocated on dwc3_debugfs_init, and should
    be released on init failure or dwc3_debugfs_exit. Btw,
    The line "dwc->root = NULL" is unnecessary, so remove it.
    
    Signed-off-by: Du, Changbin <changbin.du@intel.com>
    
    [ felipe.balbi@linux.intel.com : add another err label for the new
    	error condition ]
    
    Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
index 9ac37fe1b6a7..cebf9e38b60a 100644
--- a/drivers/usb/dwc3/debugfs.c
+++ b/drivers/usb/dwc3/debugfs.c
@@ -645,7 +645,7 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 	file = debugfs_create_regset32("regdump", S_IRUGO, root, dwc->regset);
 	if (!file) {
 		ret = -ENOMEM;
-		goto err1;
+		goto err2;
 	}
 
 	if (IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)) {
@@ -653,7 +653,7 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 				dwc, &dwc3_mode_fops);
 		if (!file) {
 			ret = -ENOMEM;
-			goto err1;
+			goto err2;
 		}
 	}
 
@@ -663,19 +663,22 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 				dwc, &dwc3_testmode_fops);
 		if (!file) {
 			ret = -ENOMEM;
-			goto err1;
+			goto err2;
 		}
 
 		file = debugfs_create_file("link_state", S_IRUGO | S_IWUSR, root,
 				dwc, &dwc3_link_state_fops);
 		if (!file) {
 			ret = -ENOMEM;
-			goto err1;
+			goto err2;
 		}
 	}
 
 	return 0;
 
+err2:
+	kfree(dwc->regset);
+
 err1:
 	debugfs_remove_recursive(root);
 
@@ -686,5 +689,5 @@ err0:
 void dwc3_debugfs_exit(struct dwc3 *dwc)
 {
 	debugfs_remove_recursive(dwc->root);
-	dwc->root = NULL;
+	kfree(dwc->regset);
 }

patch is longer but functionally equivalent.

-- 
balbi

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