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Re: [PATCH] of: Fix issue where code would fall through to error case.

Started byFrank Rowand <frowand.list@gmail.com>
First post2016-11-26 22:50 +0100
Last post2016-11-29 18:00 +0100
Articles 5 — 3 participants

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  Re: [PATCH] of: Fix issue where code would fall through to error  case. Frank Rowand <frowand.list@gmail.com> - 2016-11-26 22:50 +0100
    Re: [PATCH] of: Fix issue where code would fall through to error  case. Frank Rowand <frowand.list@gmail.com> - 2016-11-28 16:40 +0100
      Re: [PATCH] of: Fix issue where code would fall through to error case. Rob Herring <robh+dt@kernel.org> - 2016-11-29 16:10 +0100
        Re: [PATCH] of: Fix issue where code would fall through to error  case. Moritz Fischer <moritz.fischer@ettus.com> - 2016-11-29 17:00 +0100
        Re: [PATCH] of: Fix issue where code would fall through to error  case. Frank Rowand <frowand.list@gmail.com> - 2016-11-29 18:00 +0100

#1530783 — Re: [PATCH] of: Fix issue where code would fall through to error case.

FromFrank Rowand <frowand.list@gmail.com>
Date2016-11-26 22:50 +0100
SubjectRe: [PATCH] of: Fix issue where code would fall through to error case.
Message-ID<sHT17-3AO-5@gated-at.bofh.it>
On 11/23/16 13:58, Rob Herring wrote:
> On Thu, Nov 17, 2016 at 6:10 PM, Moritz Fischer
> <moritz.fischer.private@gmail.com> wrote:
>> On Thu, Nov 17, 2016 at 4:02 PM, Frank Rowand <frowand.list@gmail.com> wrote:
>>> On 11/17/16 15:40, Frank Rowand wrote:
>>>> On 11/17/16 15:25, Moritz Fischer wrote:
>>>>> No longer fall through into the error case that prints out
>>>>> an error if no error (err = 0) occurred.
>>>>>
>>>>> Fixes d9181b20a83(of: Add back an error message, restructured)
>>>>> Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
>>>>> ---
>>>>>  drivers/of/resolver.c | 6 +++++-
>>>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c
>>>>> index 783bd09..785076d 100644
>>>>> --- a/drivers/of/resolver.c
>>>>> +++ b/drivers/of/resolver.c
>>>>> @@ -358,9 +358,13 @@ int of_resolve_phandles(struct device_node *overlay)
>>>>>
>>>>>              err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
>>>>>              if (err)
>>>>> -                    break;
>>>>> +                    goto err_out;
>>>>>      }
>>>>>
>>>>> +    of_node_put(tree_symbols);
>>>>> +
>>>>> +    return 0;
>>>>> +
>>>>>  err_out:
>>>>>      pr_err("overlay phandle fixup failed: %d\n", err);
>>>>>  out:
>>>>
>>>> Thanks for catching that.
>>>>
>>>> Rob, please apply.
>>>>
>>>> Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
>>>>
>>>> -Frank
>>>
>>> On second thought, isn't the common pattern when clean up is needed for
>>> both the no-error path and the error path something like:
>>>
>>>
>>>         out:
>>>                 of_node_put(tree_symbols);
>>>                 return err;
>>>
>>>         err_out:
>>>                 pr_err("overlay phandle fixup failed: %d\n", err);
>>>                 goto out;
>>>         }
>>>
>>>
>>> I don't have a strong opinion, whatever Rob wants to take is fine with me.
>>
>> Same here. I tried to avoid the jumping back part, but if that's the
>> common pattern,
>> I can submit a v2 doing that instead.
> 
> Both are ugly. Just do:
> 
> if (err)
>   pr_err(...);
> 
> Rob

Agreed.  Thanks for the touch of sanity Rob.

-Frank

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#1531398

FromFrank Rowand <frowand.list@gmail.com>
Date2016-11-28 16:40 +0100
Message-ID<sIwc9-3Rx-9@gated-at.bofh.it>
In reply to#1530783
On 11/26/16 13:39, Frank Rowand wrote:
> On 11/23/16 13:58, Rob Herring wrote:
>> On Thu, Nov 17, 2016 at 6:10 PM, Moritz Fischer
>> <moritz.fischer.private@gmail.com> wrote:
>>> On Thu, Nov 17, 2016 at 4:02 PM, Frank Rowand <frowand.list@gmail.com> wrote:
>>>> On 11/17/16 15:40, Frank Rowand wrote:
>>>>> On 11/17/16 15:25, Moritz Fischer wrote:
>>>>>> No longer fall through into the error case that prints out
>>>>>> an error if no error (err = 0) occurred.
>>>>>>
>>>>>> Fixes d9181b20a83(of: Add back an error message, restructured)
>>>>>> Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
>>>>>> ---
>>>>>>  drivers/of/resolver.c | 6 +++++-
>>>>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c
>>>>>> index 783bd09..785076d 100644
>>>>>> --- a/drivers/of/resolver.c
>>>>>> +++ b/drivers/of/resolver.c
>>>>>> @@ -358,9 +358,13 @@ int of_resolve_phandles(struct device_node *overlay)
>>>>>>
>>>>>>              err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
>>>>>>              if (err)
>>>>>> -                    break;
>>>>>> +                    goto err_out;
>>>>>>      }
>>>>>>
>>>>>> +    of_node_put(tree_symbols);
>>>>>> +
>>>>>> +    return 0;
>>>>>> +
>>>>>>  err_out:
>>>>>>      pr_err("overlay phandle fixup failed: %d\n", err);
>>>>>>  out:
>>>>>
>>>>> Thanks for catching that.
>>>>>
>>>>> Rob, please apply.
>>>>>
>>>>> Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
>>>>>
>>>>> -Frank
>>>>
>>>> On second thought, isn't the common pattern when clean up is needed for
>>>> both the no-error path and the error path something like:
>>>>
>>>>
>>>>         out:
>>>>                 of_node_put(tree_symbols);
>>>>                 return err;
>>>>
>>>>         err_out:
>>>>                 pr_err("overlay phandle fixup failed: %d\n", err);
>>>>                 goto out;
>>>>         }
>>>>
>>>>
>>>> I don't have a strong opinion, whatever Rob wants to take is fine with me.
>>>
>>> Same here. I tried to avoid the jumping back part, but if that's the
>>> common pattern,
>>> I can submit a v2 doing that instead.
>>
>> Both are ugly. Just do:
>>
>> if (err)
>>   pr_err(...);
>>
>> Rob
> 
> Agreed.  Thanks for the touch of sanity Rob.
> 
> -Frank

I succumbed to looking only at the few lines of code above and not the
fuller context of the file that the patch applies to.

The proposed patch was fixing the problem that a normal completion
of the for loop was falling through into the err_out label.  So what
looks cleaner ("if (err) pr_err(...)") is actually not correct.

-Frank

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#1532383 — Re: [PATCH] of: Fix issue where code would fall through to error case.

FromRob Herring <robh+dt@kernel.org>
Date2016-11-29 16:10 +0100
SubjectRe: [PATCH] of: Fix issue where code would fall through to error case.
Message-ID<sIScG-1DN-21@gated-at.bofh.it>
In reply to#1531398
On Mon, Nov 28, 2016 at 9:30 AM, Frank Rowand <frowand.list@gmail.com> wrote:
> On 11/26/16 13:39, Frank Rowand wrote:
>> On 11/23/16 13:58, Rob Herring wrote:
>>> On Thu, Nov 17, 2016 at 6:10 PM, Moritz Fischer
>>> <moritz.fischer.private@gmail.com> wrote:
>>>> On Thu, Nov 17, 2016 at 4:02 PM, Frank Rowand <frowand.list@gmail.com> wrote:
>>>>> On 11/17/16 15:40, Frank Rowand wrote:
>>>>>> On 11/17/16 15:25, Moritz Fischer wrote:
>>>>>>> No longer fall through into the error case that prints out
>>>>>>> an error if no error (err = 0) occurred.
>>>>>>>
>>>>>>> Fixes d9181b20a83(of: Add back an error message, restructured)
>>>>>>> Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
>>>>>>> ---
>>>>>>>  drivers/of/resolver.c | 6 +++++-
>>>>>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>>>>>
>>>>>>> diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c
>>>>>>> index 783bd09..785076d 100644
>>>>>>> --- a/drivers/of/resolver.c
>>>>>>> +++ b/drivers/of/resolver.c
>>>>>>> @@ -358,9 +358,13 @@ int of_resolve_phandles(struct device_node *overlay)
>>>>>>>
>>>>>>>              err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
>>>>>>>              if (err)
>>>>>>> -                    break;
>>>>>>> +                    goto err_out;
>>>>>>>      }
>>>>>>>
>>>>>>> +    of_node_put(tree_symbols);
>>>>>>> +
>>>>>>> +    return 0;
>>>>>>> +
>>>>>>>  err_out:
>>>>>>>      pr_err("overlay phandle fixup failed: %d\n", err);
>>>>>>>  out:
>>>>>>
>>>>>> Thanks for catching that.
>>>>>>
>>>>>> Rob, please apply.
>>>>>>
>>>>>> Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
>>>>>>
>>>>>> -Frank
>>>>>
>>>>> On second thought, isn't the common pattern when clean up is needed for
>>>>> both the no-error path and the error path something like:
>>>>>
>>>>>
>>>>>         out:
>>>>>                 of_node_put(tree_symbols);
>>>>>                 return err;
>>>>>
>>>>>         err_out:
>>>>>                 pr_err("overlay phandle fixup failed: %d\n", err);
>>>>>                 goto out;
>>>>>         }
>>>>>
>>>>>
>>>>> I don't have a strong opinion, whatever Rob wants to take is fine with me.
>>>>
>>>> Same here. I tried to avoid the jumping back part, but if that's the
>>>> common pattern,
>>>> I can submit a v2 doing that instead.
>>>
>>> Both are ugly. Just do:
>>>
>>> if (err)
>>>   pr_err(...);
>>>
>>> Rob
>>
>> Agreed.  Thanks for the touch of sanity Rob.
>>
>> -Frank
>
> I succumbed to looking only at the few lines of code above and not the
> fuller context of the file that the patch applies to.
>
> The proposed patch was fixing the problem that a normal completion
> of the for loop was falling through into the err_out label.  So what
> looks cleaner ("if (err) pr_err(...)") is actually not correct.

What!? The *only* problem was printing the error message in the err=0
case. All that needs to be fixed is not doing that. If we do that,
then we really only need 1 goto label.

Rob

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#1532446

FromMoritz Fischer <moritz.fischer@ettus.com>
Date2016-11-29 17:00 +0100
Message-ID<sISZ4-1UF-7@gated-at.bofh.it>
In reply to#1532383
Hi Rob,

On Tue, Nov 29, 2016 at 09:06:08AM -0600, Rob Herring wrote:
> On Mon, Nov 28, 2016 at 9:30 AM, Frank Rowand <frowand.list@gmail.com> wrote:
> > On 11/26/16 13:39, Frank Rowand wrote:
> >> On 11/23/16 13:58, Rob Herring wrote:
> >>> On Thu, Nov 17, 2016 at 6:10 PM, Moritz Fischer
> >>> <moritz.fischer.private@gmail.com> wrote:
> >>>> On Thu, Nov 17, 2016 at 4:02 PM, Frank Rowand <frowand.list@gmail.com> wrote:
> >>>>> On 11/17/16 15:40, Frank Rowand wrote:
> >>>>>> On 11/17/16 15:25, Moritz Fischer wrote:
> >>>>>>> No longer fall through into the error case that prints out
> >>>>>>> an error if no error (err = 0) occurred.
> >>>>>>>
> >>>>>>> Fixes d9181b20a83(of: Add back an error message, restructured)
> >>>>>>> Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
> >>>>>>> ---
> >>>>>>>  drivers/of/resolver.c | 6 +++++-
> >>>>>>>  1 file changed, 5 insertions(+), 1 deletion(-)
> >>>>>>>
> >>>>>>> diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c
> >>>>>>> index 783bd09..785076d 100644
> >>>>>>> --- a/drivers/of/resolver.c
> >>>>>>> +++ b/drivers/of/resolver.c
> >>>>>>> @@ -358,9 +358,13 @@ int of_resolve_phandles(struct device_node *overlay)
> >>>>>>>
> >>>>>>>              err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
> >>>>>>>              if (err)
> >>>>>>> -                    break;
> >>>>>>> +                    goto err_out;
> >>>>>>>      }
> >>>>>>>
> >>>>>>> +    of_node_put(tree_symbols);
> >>>>>>> +
> >>>>>>> +    return 0;
> >>>>>>> +
> >>>>>>>  err_out:
> >>>>>>>      pr_err("overlay phandle fixup failed: %d\n", err);
> >>>>>>>  out:
> >>>>>>
> >>>>>> Thanks for catching that.
> >>>>>>
> >>>>>> Rob, please apply.
> >>>>>>
> >>>>>> Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
> >>>>>>
> >>>>>> -Frank
> >>>>>
> >>>>> On second thought, isn't the common pattern when clean up is needed for
> >>>>> both the no-error path and the error path something like:
> >>>>>
> >>>>>
> >>>>>         out:
> >>>>>                 of_node_put(tree_symbols);
> >>>>>                 return err;
> >>>>>
> >>>>>         err_out:
> >>>>>                 pr_err("overlay phandle fixup failed: %d\n", err);
> >>>>>                 goto out;
> >>>>>         }
> >>>>>
> >>>>>
> >>>>> I don't have a strong opinion, whatever Rob wants to take is fine with me.
> >>>>
> >>>> Same here. I tried to avoid the jumping back part, but if that's the
> >>>> common pattern,
> >>>> I can submit a v2 doing that instead.
> >>>
> >>> Both are ugly. Just do:
> >>>
> >>> if (err)
> >>>   pr_err(...);
> >>>
> >>> Rob
> >>
> >> Agreed.  Thanks for the touch of sanity Rob.
> >>
> >> -Frank
> >
> > I succumbed to looking only at the few lines of code above and not the
> > fuller context of the file that the patch applies to.
> >
> > The proposed patch was fixing the problem that a normal completion
> > of the for loop was falling through into the err_out label.  So what
> > looks cleaner ("if (err) pr_err(...)") is actually not correct.
> 
> What!? The *only* problem was printing the error message in the err=0
> case. All that needs to be fixed is not doing that. If we do that,
> then we really only need 1 goto label.

I think you're right. Can you look at my v3 that I sent. I also tried to
fix cases where we can just do

return 0;

vs.

err = 0;
goto err

...

err:
	of_node_put(NULL /*tree_symbols is NULL*/);
	return err;

Thanks,

Moritz

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#1532522

FromFrank Rowand <frowand.list@gmail.com>
Date2016-11-29 18:00 +0100
Message-ID<sITV8-2B3-31@gated-at.bofh.it>
In reply to#1532383
On 11/29/16 07:06, Rob Herring wrote:
> On Mon, Nov 28, 2016 at 9:30 AM, Frank Rowand <frowand.list@gmail.com> wrote:
>> On 11/26/16 13:39, Frank Rowand wrote:
>>> On 11/23/16 13:58, Rob Herring wrote:
>>>> On Thu, Nov 17, 2016 at 6:10 PM, Moritz Fischer
>>>> <moritz.fischer.private@gmail.com> wrote:
>>>>> On Thu, Nov 17, 2016 at 4:02 PM, Frank Rowand <frowand.list@gmail.com> wrote:
>>>>>> On 11/17/16 15:40, Frank Rowand wrote:
>>>>>>> On 11/17/16 15:25, Moritz Fischer wrote:
>>>>>>>> No longer fall through into the error case that prints out
>>>>>>>> an error if no error (err = 0) occurred.
>>>>>>>>
>>>>>>>> Fixes d9181b20a83(of: Add back an error message, restructured)
>>>>>>>> Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
>>>>>>>> ---
>>>>>>>>  drivers/of/resolver.c | 6 +++++-
>>>>>>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>>>>>>
>>>>>>>> diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c
>>>>>>>> index 783bd09..785076d 100644
>>>>>>>> --- a/drivers/of/resolver.c
>>>>>>>> +++ b/drivers/of/resolver.c
>>>>>>>> @@ -358,9 +358,13 @@ int of_resolve_phandles(struct device_node *overlay)
>>>>>>>>
>>>>>>>>              err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
>>>>>>>>              if (err)
>>>>>>>> -                    break;
>>>>>>>> +                    goto err_out;
>>>>>>>>      }
>>>>>>>>
>>>>>>>> +    of_node_put(tree_symbols);
>>>>>>>> +
>>>>>>>> +    return 0;
>>>>>>>> +
>>>>>>>>  err_out:
>>>>>>>>      pr_err("overlay phandle fixup failed: %d\n", err);
>>>>>>>>  out:
>>>>>>>
>>>>>>> Thanks for catching that.
>>>>>>>
>>>>>>> Rob, please apply.
>>>>>>>
>>>>>>> Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
>>>>>>>
>>>>>>> -Frank
>>>>>>
>>>>>> On second thought, isn't the common pattern when clean up is needed for
>>>>>> both the no-error path and the error path something like:
>>>>>>
>>>>>>
>>>>>>         out:
>>>>>>                 of_node_put(tree_symbols);
>>>>>>                 return err;
>>>>>>
>>>>>>         err_out:
>>>>>>                 pr_err("overlay phandle fixup failed: %d\n", err);
>>>>>>                 goto out;
>>>>>>         }
>>>>>>
>>>>>>
>>>>>> I don't have a strong opinion, whatever Rob wants to take is fine with me.
>>>>>
>>>>> Same here. I tried to avoid the jumping back part, but if that's the
>>>>> common pattern,
>>>>> I can submit a v2 doing that instead.
>>>>
>>>> Both are ugly. Just do:
>>>>
>>>> if (err)
>>>>   pr_err(...);
>>>>
>>>> Rob
>>>
>>> Agreed.  Thanks for the touch of sanity Rob.
>>>
>>> -Frank
>>
>> I succumbed to looking only at the few lines of code above and not the
>> fuller context of the file that the patch applies to.
>>
>> The proposed patch was fixing the problem that a normal completion
>> of the for loop was falling through into the err_out label.  So what
>> looks cleaner ("if (err) pr_err(...)") is actually not correct.
> 
> What!? The *only* problem was printing the error message in the err=0
> case. All that needs to be fixed is not doing that. If we do that,
> then we really only need 1 goto label.
> 
> Rob

I misread your original suggestion to mean to put the "if (err) pr_err(...)"
inside the for loop, where Moritz had made his changes.

Now I understand what you really meant, to put the "if (err) pr_err(...)"
after the for loop.

Yes, that is a good way to do it.

Sorry for the extra noise....

-Frank

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