[LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Rahul Rameshbabu via ltp]

The .adjphase operation is an operation that is implemented only by certain
PHCs. The sysfs device attribute node for querying the maximum phase
adjustment supported should not be exposed on devices that do not support
.adjphase.

Fixes: c3b60ab7a4df ("ptp: Add .getmaxphase callback to ptp_clock_info")
Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Link: https://lore.kernel.org/netdev/20230627162146.GA114473@dev-arch.thelio-3990X/
Link: https://lore.kernel.org/all/CA+G9fYtKCZeAUTtwe69iK8Xcz1mOKQzwcy49wd+imZrfj6ifXA@mail.gmail.com/
---
 drivers/ptp/ptp_sysfs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/ptp/ptp_sysfs.c b/drivers/ptp/ptp_sysfs.c
index 77219cdcd683..6e4d5456a885 100644
--- a/drivers/ptp/ptp_sysfs.c
+++ b/drivers/ptp/ptp_sysfs.c
@@ -358,6 +358,9 @@ static umode_t ptp_is_attribute_visible(struct kobject *kobj,
 		   attr == &dev_attr_max_vclocks.attr) {
 		if (ptp->is_virtual_clock)
 			mode = 0;
+	} else if (attr == &dev_attr_max_phase_adjustment.attr) {
+		if (!info->adjphase || !info->getmaxphase)
+			mode = 0;
 	}
 
 	return mode;
-- 
2.40.1


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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Nathan Chancellor]

On Tue, Jun 27, 2023 at 04:21:39PM -0700, Rahul Rameshbabu wrote:
> The .adjphase operation is an operation that is implemented only by certain
> PHCs. The sysfs device attribute node for querying the maximum phase
> adjustment supported should not be exposed on devices that do not support
> .adjphase.
> 
> Fixes: c3b60ab7a4df ("ptp: Add .getmaxphase callback to ptp_clock_info")
> Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Link: https://lore.kernel.org/netdev/20230627162146.GA114473@dev-arch.thelio-3990X/
> Link: https://lore.kernel.org/all/CA+G9fYtKCZeAUTtwe69iK8Xcz1mOKQzwcy49wd+imZrfj6ifXA@mail.gmail.com/

Thanks a lot for the fix!

Tested-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  drivers/ptp/ptp_sysfs.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/ptp/ptp_sysfs.c b/drivers/ptp/ptp_sysfs.c
> index 77219cdcd683..6e4d5456a885 100644
> --- a/drivers/ptp/ptp_sysfs.c
> +++ b/drivers/ptp/ptp_sysfs.c
> @@ -358,6 +358,9 @@ static umode_t ptp_is_attribute_visible(struct kobject *kobj,
>  		   attr == &dev_attr_max_vclocks.attr) {
>  		if (ptp->is_virtual_clock)
>  			mode = 0;
> +	} else if (attr == &dev_attr_max_phase_adjustment.attr) {
> +		if (!info->adjphase || !info->getmaxphase)
> +			mode = 0;
>  	}
>  
>  	return mode;
> -- 
> 2.40.1
> 

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Andrew Lunn]

On Tue, Jun 27, 2023 at 04:21:39PM -0700, Rahul Rameshbabu wrote:
> The .adjphase operation is an operation that is implemented only by certain
> PHCs. The sysfs device attribute node for querying the maximum phase
> adjustment supported should not be exposed on devices that do not support
> .adjphase.
> 
> Fixes: c3b60ab7a4df ("ptp: Add .getmaxphase callback to ptp_clock_info")
> Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Link: https://lore.kernel.org/netdev/20230627162146.GA114473@dev-arch.thelio-3990X/
> Link: https://lore.kernel.org/all/CA+G9fYtKCZeAUTtwe69iK8Xcz1mOKQzwcy49wd+imZrfj6ifXA@mail.gmail.com/

I think Signed-off-by should be last.

> diff --git a/drivers/ptp/ptp_sysfs.c b/drivers/ptp/ptp_sysfs.c
> index 77219cdcd683..6e4d5456a885 100644
> --- a/drivers/ptp/ptp_sysfs.c
> +++ b/drivers/ptp/ptp_sysfs.c
> @@ -358,6 +358,9 @@ static umode_t ptp_is_attribute_visible(struct kobject *kobj,
>  		   attr == &dev_attr_max_vclocks.attr) {
>  		if (ptp->is_virtual_clock)
>  			mode = 0;
> +	} else if (attr == &dev_attr_max_phase_adjustment.attr) {
> +		if (!info->adjphase || !info->getmaxphase)
> +			mode = 0;

Maybe it is time to turn this into a switch statement?

I also wounder if this really is something for net. How do you think
this patch matches against the stable rules?

    Andrew


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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Rahul Rameshbabu via ltp]

On Wed, 28 Jun, 2023 03:16:43 +0200 Andrew Lunn <andrew@lunn.ch> wrote:
> On Tue, Jun 27, 2023 at 04:21:39PM -0700, Rahul Rameshbabu wrote:
>> The .adjphase operation is an operation that is implemented only by certain
>> PHCs. The sysfs device attribute node for querying the maximum phase
>> adjustment supported should not be exposed on devices that do not support
>> .adjphase.
>> 
>> Fixes: c3b60ab7a4df ("ptp: Add .getmaxphase callback to ptp_clock_info")
>> Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
>> Reported-by: Nathan Chancellor <nathan@kernel.org>
>> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
>> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
>> Link: https://lore.kernel.org/netdev/20230627162146.GA114473@dev-arch.thelio-3990X/
>> Link: https://lore.kernel.org/all/CA+G9fYtKCZeAUTtwe69iK8Xcz1mOKQzwcy49wd+imZrfj6ifXA@mail.gmail.com/
>
> I think Signed-off-by should be last.

I can agree with this. Follows the "real route" of the patch, reports
came in and then the patch was implemented and signed-off.

>
>> diff --git a/drivers/ptp/ptp_sysfs.c b/drivers/ptp/ptp_sysfs.c
>> index 77219cdcd683..6e4d5456a885 100644
>> --- a/drivers/ptp/ptp_sysfs.c
>> +++ b/drivers/ptp/ptp_sysfs.c
>> @@ -358,6 +358,9 @@ static umode_t ptp_is_attribute_visible(struct kobject *kobj,
>>  		   attr == &dev_attr_max_vclocks.attr) {
>>  		if (ptp->is_virtual_clock)
>>  			mode = 0;
>> +	} else if (attr == &dev_attr_max_phase_adjustment.attr) {
>> +		if (!info->adjphase || !info->getmaxphase)
>> +			mode = 0;
>
> Maybe it is time to turn this into a switch statement?

I agree. However, I do not want to conflate two separate things being a
bugfix and a cleanup. I think we can do one of two options.

  1. We can take this patch as is, but I submit a subsequent cleanup patch for
  this.
  2. I can turn this into a two patch submission where the first patch
  does the conversion.

I am a fan of the first option personally.

>
> I also wounder if this really is something for net. How do you think
> this patch matches against the stable rules?

Apologize in advance but not sure I am following along. The commit for
the patch the introduces the problematic logic has made its way to net
and this patch is a fix. Therefore, isn't net the right tree to target?

https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=c3b60ab7a4dff6e6e608e685b70ddc3d6b2aca81

>
>     Andrew

Thanks,

Rahul Rameshbabu

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Andrew Lunn]

> >> diff --git a/drivers/ptp/ptp_sysfs.c b/drivers/ptp/ptp_sysfs.c
> >> index 77219cdcd683..6e4d5456a885 100644
> >> --- a/drivers/ptp/ptp_sysfs.c
> >> +++ b/drivers/ptp/ptp_sysfs.c
> >> @@ -358,6 +358,9 @@ static umode_t ptp_is_attribute_visible(struct kobject *kobj,
> >>  		   attr == &dev_attr_max_vclocks.attr) {
> >>  		if (ptp->is_virtual_clock)
> >>  			mode = 0;
> >> +	} else if (attr == &dev_attr_max_phase_adjustment.attr) {
> >> +		if (!info->adjphase || !info->getmaxphase)
> >> +			mode = 0;
> >
> > Maybe it is time to turn this into a switch statement?
> 
> I agree. However, I do not want to conflate two separate things being a
> bugfix and a cleanup. I think we can do one of two options.
> 
>   1. We can take this patch as is, but I submit a subsequent cleanup patch for
>   this.

Fine by me.

> > I also wounder if this really is something for net. How do you think
> > this patch matches against the stable rules?
> 
> Apologize in advance but not sure I am following along. The commit for
> the patch the introduces the problematic logic has made its way to net
> and this patch is a fix. Therefore, isn't net the right tree to target?

Humm. So c3b60ab7a4df is in net-next, and the tag net-next-6.5. So it
was passed to Linus yesterday for merging. You would like this fix
merged either before -rc1, or just after -rc1.

We are in the grey area where it is less clear which tree it should be
against. So it is good to explain after the --- what your intention
is, so the Maintainers get a heads up and understand what you are
trying to achieve.

I actually thought you were trying to fix an older issue, something in
6.4 or older, which is what net is mostly used for. Under those
conditions, the stable rules apply. Things like, is this fixing an
issue which really effects users....

       Andrew


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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Rahul Rameshbabu via ltp]

On Wed, 28 Jun, 2023 16:35:41 +0200 Andrew Lunn <andrew@lunn.ch> wrote:
>> > I also wounder if this really is something for net. How do you think
>> > this patch matches against the stable rules?
>> 
>> Apologize in advance but not sure I am following along. The commit for
>> the patch the introduces the problematic logic has made its way to net
>> and this patch is a fix. Therefore, isn't net the right tree to target?
>
> Humm. So c3b60ab7a4df is in net-next, and the tag net-next-6.5. So it
> was passed to Linus yesterday for merging. You would like this fix
> merged either before -rc1, or just after -rc1.

It can be after -rc1. I understand your point now from this elaboration.
Since the change is not heading towards a final release yet but a
release candidate, it's not an "urgent" patch to be applied before -rc1.

>
> We are in the grey area where it is less clear which tree it should be
> against. So it is good to explain after the --- what your intention
> is, so the Maintainers get a heads up and understand what you are
> trying to achieve.

Agreed, I could have used git notes for that in my patch generation.
Noted for the future. Just to be clear, my intention is for this fix to
make its way before the final 6.5 release (before the changes make their
way to an end user since the NULL pointer dereference when reading that
sysfs node from a PHC not supporting phase adjustment is problematic). I
think the issue being present in a release candidate is a minor problem.
Would I still keep the Fixes tag however if targeting net-next? I
remember this email from Jakub where if a Fixes tag is used, the patch
should end up in net rather than net-next. However, I fear that without
a Fixes tag, targeting net-next would cause me to miss applying this
fix before the 6.5 release.

Link: https://lore.kernel.org/netdev/20230607091909.321fc5d7@kernel.org/

----- BEGIN QUOTE -----
  We'll obviously apply our own judgment but submitter should send all
  fixes against net.
------ END QUOTE ------

I personally think this fix is "worthy" of targeting net based on the
discussion Jakub previously provided, given the impact of reading the
sysfs node on a system without this patch on PHCs that do not support
phase adjustment.

>
> I actually thought you were trying to fix an older issue, something in
> 6.4 or older, which is what net is mostly used for. Under those
> conditions, the stable rules apply. Things like, is this fixing an
> issue which really effects users....

Right, this was caught before it made its way to general users. I was
basing targeting net still from the previous conversation about Fixes
tags.

>
>        Andrew

Thanks,

Rahul Rameshbabu

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Andrew Lunn]

> It can be after -rc1. I understand your point now from this elaboration.
> Since the change is not heading towards a final release yet but a
> release candidate, it's not an "urgent" patch to be applied before -rc1.
> 
> >
> > We are in the grey area where it is less clear which tree it should be
> > against. So it is good to explain after the --- what your intention
> > is, so the Maintainers get a heads up and understand what you are
> > trying to achieve.
> 
> Agreed, I could have used git notes for that in my patch generation.
> Noted for the future. Just to be clear, my intention is for this fix to
> make its way before the final 6.5 release (before the changes make their
> way to an end user since the NULL pointer dereference when reading that
> sysfs node from a PHC not supporting phase adjustment is problematic).

A NULL pointer dereference is a valid reason for stable anyway. 

> I think the issue being present in a release candidate is a minor
> problem.  Would I still keep the Fixes tag however if targeting
> net-next?

It is useful, even for something in net-next. It is not needed for
back porting, except for making it clear back porting is not needed,
But there are some statistics gathered based on Fixes tags, etc.

     Andrew

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Jakub Kicinski]

On Wed, 28 Jun 2023 03:16:43 +0200 Andrew Lunn wrote:
> > +	} else if (attr == &dev_attr_max_phase_adjustment.attr) {
> > +		if (!info->adjphase || !info->getmaxphase)
> > +			mode = 0;  
> 
> Maybe it is time to turn this into a switch statement?

I don't think we can switch on pointers in C.
The patch is good as is, right?
(The tree we'll pick appropriately when applying.)

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Andrew Lunn]

On Wed, Jun 28, 2023 at 01:38:50PM -0700, Jakub Kicinski wrote:
> On Wed, 28 Jun 2023 03:16:43 +0200 Andrew Lunn wrote:
> > > +	} else if (attr == &dev_attr_max_phase_adjustment.attr) {
> > > +		if (!info->adjphase || !info->getmaxphase)
> > > +			mode = 0;  
> > 
> > Maybe it is time to turn this into a switch statement?
> 
> I don't think we can switch on pointers in C.

https://elixir.bootlin.com/linux/latest/source/drivers/net/phy/sfp.c#L749

Works for temperature sensors, voltage sensors, current sensors, and
power sensors. Maybe hwmon is different to what is going on here, but
both a sysfs files.

> The patch is good as is, right?

Yes.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Rahul Rameshbabu via ltp]

On Wed, 28 Jun, 2023 22:46:32 +0200 Andrew Lunn <andrew@lunn.ch> wrote:
> On Wed, Jun 28, 2023 at 01:38:50PM -0700, Jakub Kicinski wrote:
>> On Wed, 28 Jun 2023 03:16:43 +0200 Andrew Lunn wrote:
>> > > +	} else if (attr == &dev_attr_max_phase_adjustment.attr) {
>> > > +		if (!info->adjphase || !info->getmaxphase)
>> > > +			mode = 0;  
>> > 
>> > Maybe it is time to turn this into a switch statement?
>> 
>> I don't think we can switch on pointers in C.
>
> https://elixir.bootlin.com/linux/latest/source/drivers/net/phy/sfp.c#L749
>
> Works for temperature sensors, voltage sensors, current sensors, and
> power sensors. Maybe hwmon is different to what is going on here, but
> both a sysfs files.

Sorry, the only switch cases I see in the link you shared are for an
integral type enum and a u32. I do not see a pointer type being used in
a switch in sfp_hwmon_is_visible?

I believe Jakub is right about pointer types + switches in C. pointer
types are not considered integral types. Here is a compiler explorer
example to demonstrate. This slipped my mind during our discussion.

https://godbolt.org/z/nKr3x7cT8

  <source>: In function 'main':
  <source>:6:13: error: switch quantity not an integer
      6 |     switch (data) {
        |             ^~~~
  Compiler returned: 1

-- Rahul Rameshbabu

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Jakub Kicinski]

On Tue, 27 Jun 2023 16:21:39 -0700 Rahul Rameshbabu wrote:
> The .adjphase operation is an operation that is implemented only by certain
> PHCs. The sysfs device attribute node for querying the maximum phase
> adjustment supported should not be exposed on devices that do not support
> .adjphase.

Richard, ack?

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Richard Cochran]

On Thu, Jun 29, 2023 at 11:06:48AM -0700, Jakub Kicinski wrote:
> On Tue, 27 Jun 2023 16:21:39 -0700 Rahul Rameshbabu wrote:
> > The .adjphase operation is an operation that is implemented only by certain
> > PHCs. The sysfs device attribute node for querying the maximum phase
> > adjustment supported should not be exposed on devices that do not support
> > .adjphase.
> 
> Richard, ack?

yes

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Richard Cochran]

On Tue, Jun 27, 2023 at 04:21:39PM -0700, Rahul Rameshbabu wrote:
> The .adjphase operation is an operation that is implemented only by certain
> PHCs. The sysfs device attribute node for querying the maximum phase
> adjustment supported should not be exposed on devices that do not support
> .adjphase.
> 
> Fixes: c3b60ab7a4df ("ptp: Add .getmaxphase callback to ptp_clock_info")
> Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Link: https://lore.kernel.org/netdev/20230627162146.GA114473@dev-arch.thelio-3990X/
> Link: https://lore.kernel.org/all/CA+G9fYtKCZeAUTtwe69iK8Xcz1mOKQzwcy49wd+imZrfj6ifXA@mail.gmail.com/

Acked-by: Richard Cochran <richardcochran@gmail.com>

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Petr Vorel]

Hi all,

> The .adjphase operation is an operation that is implemented only by certain
> PHCs. The sysfs device attribute node for querying the maximum phase
> adjustment supported should not be exposed on devices that do not support
> .adjphase.

Reviewed-by: Petr Vorel <pvorel@suse.cz>

I wonder why LTP was Cc'ed.

Kind regards,
Petr

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[Cyril Hrubis]

Hi!
> I wonder why LTP was Cc'ed.

Since the NULL dereference was found by the read_all LTP test.

-- 
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chrubis@suse.cz

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Re: [LTP] [PATCH net v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 27 Jun 2023 16:21:39 -0700 you wrote:
> The .adjphase operation is an operation that is implemented only by certain
> PHCs. The sysfs device attribute node for querying the maximum phase
> adjustment supported should not be exposed on devices that do not support
> .adjphase.
> 
> Fixes: c3b60ab7a4df ("ptp: Add .getmaxphase callback to ptp_clock_info")
> Signed-off-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> Link: https://lore.kernel.org/netdev/20230627162146.GA114473@dev-arch.thelio-3990X/
> Link: https://lore.kernel.org/all/CA+G9fYtKCZeAUTtwe69iK8Xcz1mOKQzwcy49wd+imZrfj6ifXA@mail.gmail.com/
> 
> [...]

Here is the summary with links:
  - [net,v1] ptp: Make max_phase_adjustment sysfs device attribute invisible when not supported
    https://git.kernel.org/netdev/net/c/2c5d234d7f55

You are awesome, thank you!
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