Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card_worker()

[Kalle Valo]

Julia Lawall  writes:

> On Sat, 2 Jan 2016, SF Markus Elfring wrote:
>
>> >> Move the jump label directly before the desired log statement
>> >> so that the variable "err" will not be checked once more
>> >> after it was determined that a function call failed.
>> >> Use the identifier "report_failure" instead of the label "err".
>> > 
>> >Why?
>> 
>> I suggest to reconsider the places with which such a jump label
>> is connected.
>> 
>> 
>> > The code was smart enough
>> 
>> Which action should really be performed after a failure was detected
>> and handled a bit already?
>> 
>> * Another condition check
>> 
>> * Just additional error logging
>> 
>> 
>> > and you're making it uglier that it needs to be.
>> 
>> I assume that a software development taste can evolve, can't it?
>
> So far, you have gotten several down votes for this kind of change, and no 
> enthusiasm.
>
> Admittedly, this is a trivial case, because there are no local variables, 
> but do you actually know the semantics in C of a jump into a block?  And 
> if you do know, do you think that this semantics is common knowledge?  And 
> do you really think that introducing poorly understandable code is really 
> worth saving an if test of a single variable on a non-critical path?
>
> Most of the kernel code is not performance critical at the level of a 
> single if test.  So the goal should be for the code to be easy to 
> understand and robust to change.  The code that is performance critical, 
> you should probably not touch, ever.  The people who wrote it knew what 
> was important and what was not.

Very well said! Only optimise something you can measure.

I'm dropping this patch.

-- 
Kalle Valo

Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card_worker()

[Kalle Valo]

Julia Lawall  writes:

> On Sat, 2 Jan 2016, SF Markus Elfring wrote:
>
>> >> Move the jump label directly before the desired log statement
>> >> so that the variable "err" will not be checked once more
>> >> after it was determined that a function call failed.
>> >> Use the identifier "report_failure" instead of the label "err".
>> > 
>> >Why?
>> 
>> I suggest to reconsider the places with which such a jump label
>> is connected.
>> 
>> 
>> > The code was smart enough
>> 
>> Which action should really be performed after a failure was detected
>> and handled a bit already?
>> 
>> * Another condition check
>> 
>> * Just additional error logging
>> 
>> 
>> > and you're making it uglier that it needs to be.
>> 
>> I assume that a software development taste can evolve, can't it?
>
> So far, you have gotten several down votes for this kind of change, and no 
> enthusiasm.
>
> Admittedly, this is a trivial case, because there are no local variables, 
> but do you actually know the semantics in C of a jump into a block?  And 
> if you do know, do you think that this semantics is common knowledge?  And 
> do you really think that introducing poorly understandable code is really 
> worth saving an if test of a single variable on a non-critical path?
>
> Most of the kernel code is not performance critical at the level of a 
> single if test.  So the goal should be for the code to be easy to 
> understand and robust to change.  The code that is performance critical, 
> you should probably not touch, ever.  The people who wrote it knew what 
> was important and what was not.

Very well said! Only optimise something you can measure.

I'm dropping this patch.

-- 
Kalle Valo

Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card_worker()

[Julia Lawall]

On Sat, 2 Jan 2016, SF Markus Elfring wrote:

> >> Move the jump label directly before the desired log statement
> >> so that the variable "err" will not be checked once more
> >> after it was determined that a function call failed.
> >> Use the identifier "report_failure" instead of the label "err".
> > 
> >Why?
> 
> I suggest to reconsider the places with which such a jump label
> is connected.
> 
> 
> > The code was smart enough
> 
> Which action should really be performed after a failure was detected
> and handled a bit already?
> 
> * Another condition check
> 
> * Just additional error logging
> 
> 
> > and you're making it uglier that it needs to be.
> 
> I assume that a software development taste can evolve, can't it?

So far, you have gotten several down votes for this kind of change, and no 
enthusiasm.

Admittedly, this is a trivial case, because there are no local variables, 
but do you actually know the semantics in C of a jump into a block?  And 
if you do know, do you think that this semantics is common knowledge?  And 
do you really think that introducing poorly understandable code is really 
worth saving an if test of a single variable on a non-critical path?

Most of the kernel code is not performance critical at the level of a 
single if test.  So the goal should be for the code to be easy to 
understand and robust to change.  The code that is performance critical, 
you should probably not touch, ever.  The people who wrote it knew what 
was important and what was not.

julia
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Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card_worker()

[SF Markus Elfring]

>> Move the jump label directly before the desired log statement
>> so that the variable "err" will not be checked once more
>> after it was determined that a function call failed.
>> Use the identifier "report_failure" instead of the label "err".
> 
>Why?

I suggest to reconsider the places with which such a jump label
is connected.


> The code was smart enough

Which action should really be performed after a failure was detected
and handled a bit already?

* Another condition check

* Just additional error logging


> and you're making it uglier that it needs to be.

I assume that a software development taste can evolve, can't it?

Regards,
Markus
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Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card_worker()

[SF Markus Elfring]

>> Move the jump label directly before the desired log statement
>> so that the variable "err" will not be checked once more
>> after it was determined that a function call failed.
>> Use the identifier "report_failure" instead of the label "err".
> 
>Why?

I suggest to reconsider the places with which such a jump label
is connected.


> The code was smart enough

Which action should really be performed after a failure was detected
and handled a bit already?

* Another condition check

* Just additional error logging


> and you're making it uglier that it needs to be.

I assume that a software development taste can evolve, can't it?

Regards,
Markus
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the body of a message to majord...@vger.kernel.org
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Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card_worker()

[Julia Lawall]

On Sat, 2 Jan 2016, SF Markus Elfring wrote:

> >> Move the jump label directly before the desired log statement
> >> so that the variable "err" will not be checked once more
> >> after it was determined that a function call failed.
> >> Use the identifier "report_failure" instead of the label "err".
> > 
> >Why?
> 
> I suggest to reconsider the places with which such a jump label
> is connected.
> 
> 
> > The code was smart enough
> 
> Which action should really be performed after a failure was detected
> and handled a bit already?
> 
> * Another condition check
> 
> * Just additional error logging
> 
> 
> > and you're making it uglier that it needs to be.
> 
> I assume that a software development taste can evolve, can't it?

So far, you have gotten several down votes for this kind of change, and no 
enthusiasm.

Admittedly, this is a trivial case, because there are no local variables, 
but do you actually know the semantics in C of a jump into a block?  And 
if you do know, do you think that this semantics is common knowledge?  And 
do you really think that introducing poorly understandable code is really 
worth saving an if test of a single variable on a non-critical path?

Most of the kernel code is not performance critical at the level of a 
single if test.  So the goal should be for the code to be easy to 
understand and robust to change.  The code that is performance critical, 
you should probably not touch, ever.  The people who wrote it knew what 
was important and what was not.

julia
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Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card_worker()

[Sergei Shtylyov]

Hello

On 1/2/2016 12:33 AM, SF Markus Elfring wrote:


From: Markus Elfring 
Date: Fri, 1 Jan 2016 22:27:20 +0100

This issue was detected by using the Coccinelle software.

Move the jump label directly before the desired log statement
so that the variable "err" will not be checked once more
after it was determined that a function call failed.
Use the identifier "report_failure" instead of the label "err".


   Why? The code was smart enough and you're making it uglier that it needs 
to be.



Signed-off-by: Markus Elfring 


MBR, Sergei

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Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card_worker()

[Julia Lawall]

On Fri, 1 Jan 2016, SF Markus Elfring wrote:

> From: Markus Elfring 
> Date: Fri, 1 Jan 2016 22:27:20 +0100
> 
> This issue was detected by using the Coccinelle software.
> 
> Move the jump label directly before the desired log statement
> so that the variable "err" will not be checked once more
> after it was determined that a function call failed.

Putting a label inside an if is ugly.

julia

> Use the identifier "report_failure" instead of the label "err".
> 
> Signed-off-by: Markus Elfring 
> ---
>  drivers/net/wireless/marvell/libertas/if_spi.c | 11 ++-
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/wireless/marvell/libertas/if_spi.c 
> b/drivers/net/wireless/marvell/libertas/if_spi.c
> index 82c0796..c9ae27e 100644
> --- a/drivers/net/wireless/marvell/libertas/if_spi.c
> +++ b/drivers/net/wireless/marvell/libertas/if_spi.c
> @@ -880,18 +880,18 @@ static void if_spi_host_to_card_worker(struct 
> work_struct *work)
>   );
>   if (err) {
>   netdev_err(priv->dev, "I/O error\n");
> - goto err;
> + goto report_failure;
>   }
>  
>   if (hiStatus & IF_SPI_HIST_CMD_UPLOAD_RDY) {
>   err = if_spi_c2h_cmd(card);
>   if (err)
> - goto err;
> + goto report_failure;
>   }
>   if (hiStatus & IF_SPI_HIST_RX_UPLOAD_RDY) {
>   err = if_spi_c2h_data(card);
>   if (err)
> - goto err;
> + goto report_failure;
>   }
>  
>   /*
> @@ -940,9 +940,10 @@ static void if_spi_host_to_card_worker(struct 
> work_struct *work)
>   if (hiStatus & IF_SPI_HIST_CARD_EVENT)
>   if_spi_e2h(card);
>  
> -err:
> - if (err)
> + if (err) {
> +report_failure:
>   netdev_err(priv->dev, "%s: got error %d\n", __func__, err);
> + }
>  
>   lbs_deb_leave(LBS_DEB_SPI);
>  }
> -- 
> 2.6.3
> 
> --
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Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card_worker()

[Julia Lawall]

On Fri, 1 Jan 2016, SF Markus Elfring wrote:

> From: Markus Elfring 
> Date: Fri, 1 Jan 2016 22:27:20 +0100
> 
> This issue was detected by using the Coccinelle software.
> 
> Move the jump label directly before the desired log statement
> so that the variable "err" will not be checked once more
> after it was determined that a function call failed.

Putting a label inside an if is ugly.

julia

> Use the identifier "report_failure" instead of the label "err".
> 
> Signed-off-by: Markus Elfring 
> ---
>  drivers/net/wireless/marvell/libertas/if_spi.c | 11 ++-
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/wireless/marvell/libertas/if_spi.c 
> b/drivers/net/wireless/marvell/libertas/if_spi.c
> index 82c0796..c9ae27e 100644
> --- a/drivers/net/wireless/marvell/libertas/if_spi.c
> +++ b/drivers/net/wireless/marvell/libertas/if_spi.c
> @@ -880,18 +880,18 @@ static void if_spi_host_to_card_worker(struct 
> work_struct *work)
>   );
>   if (err) {
>   netdev_err(priv->dev, "I/O error\n");
> - goto err;
> + goto report_failure;
>   }
>  
>   if (hiStatus & IF_SPI_HIST_CMD_UPLOAD_RDY) {
>   err = if_spi_c2h_cmd(card);
>   if (err)
> - goto err;
> + goto report_failure;
>   }
>   if (hiStatus & IF_SPI_HIST_RX_UPLOAD_RDY) {
>   err = if_spi_c2h_data(card);
>   if (err)
> - goto err;
> + goto report_failure;
>   }
>  
>   /*
> @@ -940,9 +940,10 @@ static void if_spi_host_to_card_worker(struct 
> work_struct *work)
>   if (hiStatus & IF_SPI_HIST_CARD_EVENT)
>   if_spi_e2h(card);
>  
> -err:
> - if (err)
> + if (err) {
> +report_failure:
>   netdev_err(priv->dev, "%s: got error %d\n", __func__, err);
> + }
>  
>   lbs_deb_leave(LBS_DEB_SPI);
>  }
> -- 
> 2.6.3
> 
> --
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Re: [PATCH] net-libertas: Better exception handling in if_spi_host_to_card_worker()

[Sergei Shtylyov]

Hello

On 1/2/2016 12:33 AM, SF Markus Elfring wrote:


From: Markus Elfring 
Date: Fri, 1 Jan 2016 22:27:20 +0100

This issue was detected by using the Coccinelle software.

Move the jump label directly before the desired log statement
so that the variable "err" will not be checked once more
after it was determined that a function call failed.
Use the identifier "report_failure" instead of the label "err".


   Why? The code was smart enough and you're making it uglier that it needs 
to be.



Signed-off-by: Markus Elfring 


MBR, Sergei

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