[RESEND PATCH] drm: Remove obsolete "This is gross" comment

[RESEND PATCH] drm: Remove obsolete "This is gross" comment

[Haneen Mohammed]

Remove obsolete comment which was initially added in 2008 to annotate
that idr_find() was used before idr_remove() since idr_remove() didn't
use to return feedback. The comment now is irrelevant with
commit f6cd7daecff5 ("drm: Release driver references to handle before
making it available again").

Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
---
 drivers/gpu/drm/drm_gem.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index c55f338..b9bddaa 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -282,15 +282,6 @@ drm_gem_handle_delete(struct drm_file *filp, u32 handle)
 {
 	struct drm_gem_object *obj;
 
-	/* This is gross. The idr system doesn't let us try a delete and
-	 * return an error code.  It just spews if you fail at deleting.
-	 * So, we have to grab a lock around finding the object and then
-	 * doing the delete on it and dropping the refcount, or the user
-	 * could race us to double-decrement the refcount and cause a
-	 * use-after-free later.  Given the frequency of our handle lookups,
-	 * we may want to use ida for number allocation and a hash table
-	 * for the pointers, anyway.
-	 */
 	spin_lock(&filp->table_lock);
 
 	/* Check if we currently have a reference on the object */
-- 
2.7.4

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Re: [Outreachy kernel] [RESEND PATCH] drm: Remove obsolete "This is gross" comment

[Julia Lawall]

On Thu, 21 Sep 2017, Haneen Mohammed wrote:

> Remove obsolete comment which was initially added in 2008 to annotate
> that idr_find() was used before idr_remove() since idr_remove() didn't
> use to return feedback. The comment now is irrelevant with
> commit f6cd7daecff5 ("drm: Release driver references to handle before
> making it available again").

Why did you send it again?

julia

>
> Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
> ---
>  drivers/gpu/drm/drm_gem.c | 9 ---------
>  1 file changed, 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> index c55f338..b9bddaa 100644
> --- a/drivers/gpu/drm/drm_gem.c
> +++ b/drivers/gpu/drm/drm_gem.c
> @@ -282,15 +282,6 @@ drm_gem_handle_delete(struct drm_file *filp, u32 handle)
>  {
>  	struct drm_gem_object *obj;
>
> -	/* This is gross. The idr system doesn't let us try a delete and
> -	 * return an error code.  It just spews if you fail at deleting.
> -	 * So, we have to grab a lock around finding the object and then
> -	 * doing the delete on it and dropping the refcount, or the user
> -	 * could race us to double-decrement the refcount and cause a
> -	 * use-after-free later.  Given the frequency of our handle lookups,
> -	 * we may want to use ida for number allocation and a hash table
> -	 * for the pointers, anyway.
> -	 */
>  	spin_lock(&filp->table_lock);
>
>  	/* Check if we currently have a reference on the object */
> --
> 2.7.4
>
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Re: [Outreachy kernel] [RESEND PATCH] drm: Remove obsolete "This is gross" comment

[Haneen Mohammed]

On Thu, Sep 21, 2017 at 11:16:44PM +0200, Julia Lawall wrote:
> 
> 
> On Thu, 21 Sep 2017, Haneen Mohammed wrote:
> 
> > Remove obsolete comment which was initially added in 2008 to annotate
> > that idr_find() was used before idr_remove() since idr_remove() didn't
> > use to return feedback. The comment now is irrelevant with
> > commit f6cd7daecff5 ("drm: Release driver references to handle before
> > making it available again").
> 
> Why did you send it again?
> 
> julia
> 

I forgot to include the dri-devel mailing list for the first patch.

Haneen

> >
> > Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
> > ---
> >  drivers/gpu/drm/drm_gem.c | 9 ---------
> >  1 file changed, 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> > index c55f338..b9bddaa 100644
> > --- a/drivers/gpu/drm/drm_gem.c
> > +++ b/drivers/gpu/drm/drm_gem.c
> > @@ -282,15 +282,6 @@ drm_gem_handle_delete(struct drm_file *filp, u32 handle)
> >  {
> >  	struct drm_gem_object *obj;
> >
> > -	/* This is gross. The idr system doesn't let us try a delete and
> > -	 * return an error code.  It just spews if you fail at deleting.
> > -	 * So, we have to grab a lock around finding the object and then
> > -	 * doing the delete on it and dropping the refcount, or the user
> > -	 * could race us to double-decrement the refcount and cause a
> > -	 * use-after-free later.  Given the frequency of our handle lookups,
> > -	 * we may want to use ida for number allocation and a hash table
> > -	 * for the pointers, anyway.
> > -	 */
> >  	spin_lock(&filp->table_lock);
> >
> >  	/* Check if we currently have a reference on the object */
> > --
> > 2.7.4
> >
> > --
> > You received this message because you are subscribed to the Google Groups "outreachy-kernel" group.
> > To unsubscribe from this group and stop receiving emails from it, send an email to outreachy-kernel+unsubscribe@googlegroups.com.
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> > To view this discussion on the web visit https://groups.google.com/d/msgid/outreachy-kernel/20170921210424.GA21951%40Haneen.
> > For more options, visit https://groups.google.com/d/optout.
> >
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Re: [Outreachy kernel] [RESEND PATCH] drm: Remove obsolete "This is gross" comment

[Julia Lawall]

On Thu, 21 Sep 2017, Haneen Mohammed wrote:

> On Thu, Sep 21, 2017 at 11:16:44PM +0200, Julia Lawall wrote:
> >
> >
> > On Thu, 21 Sep 2017, Haneen Mohammed wrote:
> >
> > > Remove obsolete comment which was initially added in 2008 to annotate
> > > that idr_find() was used before idr_remove() since idr_remove() didn't
> > > use to return feedback. The comment now is irrelevant with
> > > commit f6cd7daecff5 ("drm: Release driver references to handle before
> > > making it available again").
> >
> > Why did you send it again?
> >
> > julia
> >
>
> I forgot to include the dri-devel mailing list for the first patch.

OK, it should have been a v2 with a comment about what changed.  Even if
it is not a technical issue, it saves people wondering about what
happened.

julia

>
> Haneen
>
> > >
> > > Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
> > > ---
> > >  drivers/gpu/drm/drm_gem.c | 9 ---------
> > >  1 file changed, 9 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> > > index c55f338..b9bddaa 100644
> > > --- a/drivers/gpu/drm/drm_gem.c
> > > +++ b/drivers/gpu/drm/drm_gem.c
> > > @@ -282,15 +282,6 @@ drm_gem_handle_delete(struct drm_file *filp, u32 handle)
> > >  {
> > >  	struct drm_gem_object *obj;
> > >
> > > -	/* This is gross. The idr system doesn't let us try a delete and
> > > -	 * return an error code.  It just spews if you fail at deleting.
> > > -	 * So, we have to grab a lock around finding the object and then
> > > -	 * doing the delete on it and dropping the refcount, or the user
> > > -	 * could race us to double-decrement the refcount and cause a
> > > -	 * use-after-free later.  Given the frequency of our handle lookups,
> > > -	 * we may want to use ida for number allocation and a hash table
> > > -	 * for the pointers, anyway.
> > > -	 */
> > >  	spin_lock(&filp->table_lock);
> > >
> > >  	/* Check if we currently have a reference on the object */
> > > --
> > > 2.7.4
> > >
> > > --
> > > You received this message because you are subscribed to the Google Groups "outreachy-kernel" group.
> > > To unsubscribe from this group and stop receiving emails from it, send an email to outreachy-kernel+unsubscribe@googlegroups.com.
> > > To post to this group, send email to outreachy-kernel@googlegroups.com.
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> > > For more options, visit https://groups.google.com/d/optout.
> > >
>
> --
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Re: [Outreachy kernel] [RESEND PATCH] drm: Remove obsolete "This is gross" comment

[Daniel Vetter]

On Thu, Sep 21, 2017 at 03:04:24PM -0600, Haneen Mohammed wrote:
> Remove obsolete comment which was initially added in 2008 to annotate
> that idr_find() was used before idr_remove() since idr_remove() didn't
> use to return feedback. The comment now is irrelevant with
> commit f6cd7daecff5 ("drm: Release driver references to handle before
> making it available again").

Personally I'd have added a lot more of the research story you've detailed
in the private mails, just to show the work you've done. But the terse
version is ok too ofc.

> Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>

Applied to drm-misc-next, thanks.
-Daniel

> ---
>  drivers/gpu/drm/drm_gem.c | 9 ---------
>  1 file changed, 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> index c55f338..b9bddaa 100644
> --- a/drivers/gpu/drm/drm_gem.c
> +++ b/drivers/gpu/drm/drm_gem.c
> @@ -282,15 +282,6 @@ drm_gem_handle_delete(struct drm_file *filp, u32 handle)
>  {
>  	struct drm_gem_object *obj;
>  
> -	/* This is gross. The idr system doesn't let us try a delete and
> -	 * return an error code.  It just spews if you fail at deleting.
> -	 * So, we have to grab a lock around finding the object and then
> -	 * doing the delete on it and dropping the refcount, or the user
> -	 * could race us to double-decrement the refcount and cause a
> -	 * use-after-free later.  Given the frequency of our handle lookups,
> -	 * we may want to use ida for number allocation and a hash table
> -	 * for the pointers, anyway.
> -	 */
>  	spin_lock(&filp->table_lock);
>  
>  	/* Check if we currently have a reference on the object */
> -- 
> 2.7.4
> 
> -- 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [Outreachy kernel] [RESEND PATCH] drm: Remove obsolete "This is gross" comment

[Haneen Mohammed]

On Tue, Sep 26, 2017 at 07:24:38AM +0200, Daniel Vetter wrote:
> On Thu, Sep 21, 2017 at 03:04:24PM -0600, Haneen Mohammed wrote:
> > Remove obsolete comment which was initially added in 2008 to annotate
> > that idr_find() was used before idr_remove() since idr_remove() didn't
> > use to return feedback. The comment now is irrelevant with
> > commit f6cd7daecff5 ("drm: Release driver references to handle before
> > making it available again").
> 
> Personally I'd have added a lot more of the research story you've detailed
> in the private mails, just to show the work you've done. But the terse
> version is ok too ofc.
> 
> > Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
> 
> Applied to drm-misc-next, thanks.
> -Daniel
> 

My bad, I was afraid to add too much details as I always read commit
message should be concise that I then ended up with too little. 

I will try next time to add the necessary information. 

Thank you!
Haneen

> > ---
> >  drivers/gpu/drm/drm_gem.c | 9 ---------
> >  1 file changed, 9 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> > index c55f338..b9bddaa 100644
> > --- a/drivers/gpu/drm/drm_gem.c
> > +++ b/drivers/gpu/drm/drm_gem.c
> > @@ -282,15 +282,6 @@ drm_gem_handle_delete(struct drm_file *filp, u32 handle)
> >  {
> >  	struct drm_gem_object *obj;
> >  
> > -	/* This is gross. The idr system doesn't let us try a delete and
> > -	 * return an error code.  It just spews if you fail at deleting.
> > -	 * So, we have to grab a lock around finding the object and then
> > -	 * doing the delete on it and dropping the refcount, or the user
> > -	 * could race us to double-decrement the refcount and cause a
> > -	 * use-after-free later.  Given the frequency of our handle lookups,
> > -	 * we may want to use ida for number allocation and a hash table
> > -	 * for the pointers, anyway.
> > -	 */
> >  	spin_lock(&filp->table_lock);
> >  
> >  	/* Check if we currently have a reference on the object */
> > -- 
> > 2.7.4
> > 
> > -- 
> > You received this message because you are subscribed to the Google Groups "outreachy-kernel" group.
> > To unsubscribe from this group and stop receiving emails from it, send an email to outreachy-kernel+unsubscribe@googlegroups.com.
> > To post to this group, send email to outreachy-kernel@googlegroups.com.
> > To view this discussion on the web visit https://groups.google.com/d/msgid/outreachy-kernel/20170921210424.GA21951%40Haneen.
> > For more options, visit https://groups.google.com/d/optout.
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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