diff mbox series

[v3,2/5] thermal/drivers/armada: convert to use devm_request_threaded_irq_emsg()

Message ID 20230703090455.62101-3-frank.li@vivo.com
State New
Headers
Series introduce devm_request_threaded_irq_emsg() |

Commit Message

李扬韬 July 3, 2023, 9:04 a.m. UTC 
  There are more than 700 calls to the devm_request_threaded_irq method.
Most drivers only request one interrupt resource, and these error
messages are basically the same. If error messages are printed
everywhere, more than 1000 lines of code can be saved by removing the
msg in the driver.

And tglx point out that:

  If we actually look at the call sites of
  devm_request_threaded_irq() then the vast majority of them print more or
  less lousy error messages. A quick grep/sed/awk/sort/uniq revealed

     519 messages total (there are probably more)

     352 unique messages

     323 unique messages after lower casing

         Those 323 are mostly just variants of the same patterns with
         slight modifications in formatting and information provided.

     186 of these messages do not deliver any useful information,
         e.g. "no irq", "

     The most useful one of all is: "could request wakeup irq: %d"

  So there is certainly an argument to be made that this particular
  function should print a well formatted and informative error message.

  It's not a general allocator like kmalloc(). It's specialized and in the
  vast majority of cases failing to request the interrupt causes the
  device probe to fail. So having proper and consistent information why
  the device cannot be used _is_ useful.

Let's use devm_request_threaded_irq_emsg(), which ensure that all error
handling branches print error information. In this way, when this function
fails, the upper-layer functions can directly return an error code without
missing debugging information. Otherwise, the error message will be
printed redundantly or missing.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Yangtao Li <frank.li@vivo.com>
---
 drivers/thermal/armada_thermal.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

Comments

Miquel Raynal July 4, 2023, 8:46 a.m. UTC | #1 
Hi Yangtao,

frank.li@vivo.com wrote on Mon,  3 Jul 2023 17:04:51 +0800:

> There are more than 700 calls to the devm_request_threaded_irq method.
> Most drivers only request one interrupt resource, and these error
> messages are basically the same. If error messages are printed
> everywhere, more than 1000 lines of code can be saved by removing the
> msg in the driver.
> 
> And tglx point out that:
> 
>   If we actually look at the call sites of
>   devm_request_threaded_irq() then the vast majority of them print more or
>   less lousy error messages. A quick grep/sed/awk/sort/uniq revealed
> 
>      519 messages total (there are probably more)
> 
>      352 unique messages
> 
>      323 unique messages after lower casing
> 
>          Those 323 are mostly just variants of the same patterns with
>          slight modifications in formatting and information provided.
> 
>      186 of these messages do not deliver any useful information,
>          e.g. "no irq", "
> 
>      The most useful one of all is: "could request wakeup irq: %d"
> 
>   So there is certainly an argument to be made that this particular
>   function should print a well formatted and informative error message.
> 
>   It's not a general allocator like kmalloc(). It's specialized and in the
>   vast majority of cases failing to request the interrupt causes the
>   device probe to fail. So having proper and consistent information why
>   the device cannot be used _is_ useful.
> 
> Let's use devm_request_threaded_irq_emsg(), which ensure that all error
> handling branches print error information. In this way, when this function
> fails, the upper-layer functions can directly return an error code without
> missing debugging information. Otherwise, the error message will be
> printed redundantly or missing.
> 
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Yangtao Li <frank.li@vivo.com>
> ---
>  drivers/thermal/armada_thermal.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
> index 9f6dc4fc9112..a5e140643f00 100644
> --- a/drivers/thermal/armada_thermal.c
> +++ b/drivers/thermal/armada_thermal.c
> @@ -913,15 +913,12 @@ static int armada_thermal_probe(struct platform_device *pdev)
>  
>  	/* The overheat interrupt feature is not mandatory */
>  	if (irq > 0) {
> -		ret = devm_request_threaded_irq(&pdev->dev, irq,
> -						armada_overheat_isr,
> -						armada_overheat_isr_thread,
> -						0, NULL, priv);
> -		if (ret) {
> -			dev_err(&pdev->dev, "Cannot request threaded IRQ %d\n",
> -				irq);
> +		ret = devm_request_threaded_irq_emsg(&pdev->dev, irq,
> +						     armada_overheat_isr,
> +						     armada_overheat_isr_thread,
> +						     0, NULL, priv, NULL);
> +		if (ret)

I don't see a patch renaming this helper with s/emsg//, do you plan to
keep it like that? I bet nobody outside of this series will notice the
new helper and will continue to add error messages because it kind
of feels "right" to do so.

I would rather prefer returning to the original function name which
everybody knows/uses.

Anyhow, I'm fine with the idea of dropping custom error messages, so
whatever the final solution:

Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>

Thanks,
Miquèl
Uwe Kleine-König July 4, 2023, 2:22 p.m. UTC | #2 
Hello Miquel,

On Tue, Jul 04, 2023 at 10:46:08AM +0200, Miquel Raynal wrote:
> Hi Yangtao,
> 
> frank.li@vivo.com wrote on Mon,  3 Jul 2023 17:04:51 +0800:
> 
> > There are more than 700 calls to the devm_request_threaded_irq method.
> > Most drivers only request one interrupt resource, and these error
> > messages are basically the same. If error messages are printed
> > everywhere, more than 1000 lines of code can be saved by removing the
> > msg in the driver.
> > 
> > And tglx point out that:
> > 
> >   If we actually look at the call sites of
> >   devm_request_threaded_irq() then the vast majority of them print more or
> >   less lousy error messages. A quick grep/sed/awk/sort/uniq revealed
> > 
> >      519 messages total (there are probably more)
> > 
> >      352 unique messages
> > 
> >      323 unique messages after lower casing
> > 
> >          Those 323 are mostly just variants of the same patterns with
> >          slight modifications in formatting and information provided.
> > 
> >      186 of these messages do not deliver any useful information,
> >          e.g. "no irq", "
> > 
> >      The most useful one of all is: "could request wakeup irq: %d"
> > 
> >   So there is certainly an argument to be made that this particular
> >   function should print a well formatted and informative error message.
> > 
> >   It's not a general allocator like kmalloc(). It's specialized and in the
> >   vast majority of cases failing to request the interrupt causes the
> >   device probe to fail. So having proper and consistent information why
> >   the device cannot be used _is_ useful.
> > 
> > Let's use devm_request_threaded_irq_emsg(), which ensure that all error
> > handling branches print error information. In this way, when this function
> > fails, the upper-layer functions can directly return an error code without
> > missing debugging information. Otherwise, the error message will be
> > printed redundantly or missing.
> > 
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Signed-off-by: Yangtao Li <frank.li@vivo.com>
> > ---
> >  drivers/thermal/armada_thermal.c | 13 +++++--------
> >  1 file changed, 5 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
> > index 9f6dc4fc9112..a5e140643f00 100644
> > --- a/drivers/thermal/armada_thermal.c
> > +++ b/drivers/thermal/armada_thermal.c
> > @@ -913,15 +913,12 @@ static int armada_thermal_probe(struct platform_device *pdev)
> >  
> >  	/* The overheat interrupt feature is not mandatory */
> >  	if (irq > 0) {
> > -		ret = devm_request_threaded_irq(&pdev->dev, irq,
> > -						armada_overheat_isr,
> > -						armada_overheat_isr_thread,
> > -						0, NULL, priv);
> > -		if (ret) {
> > -			dev_err(&pdev->dev, "Cannot request threaded IRQ %d\n",
> > -				irq);
> > +		ret = devm_request_threaded_irq_emsg(&pdev->dev, irq,
> > +						     armada_overheat_isr,
> > +						     armada_overheat_isr_thread,
> > +						     0, NULL, priv, NULL);
> > +		if (ret)
> 
> I don't see a patch renaming this helper with s/emsg//, do you plan to
> keep it like that? I bet nobody outside of this series will notice the
> new helper and will continue to add error messages because it kind
> of feels "right" to do so.
> 
> I would rather prefer returning to the original function name which
> everybody knows/uses.

See https://lore.kernel.org/lkml/87h6qpyzkd.ffs@tglx for why there is a
new function name.

Best regards
Uwe
Miquel Raynal July 4, 2023, 2:29 p.m. UTC | #3 
Hi Uwe,

u.kleine-koenig@pengutronix.de wrote on Tue, 4 Jul 2023 16:22:27 +0200:

> Hello Miquel,
> 
> On Tue, Jul 04, 2023 at 10:46:08AM +0200, Miquel Raynal wrote:
> > Hi Yangtao,
> > 
> > frank.li@vivo.com wrote on Mon,  3 Jul 2023 17:04:51 +0800:
> >   
> > > There are more than 700 calls to the devm_request_threaded_irq method.
> > > Most drivers only request one interrupt resource, and these error
> > > messages are basically the same. If error messages are printed
> > > everywhere, more than 1000 lines of code can be saved by removing the
> > > msg in the driver.
> > > 
> > > And tglx point out that:
> > > 
> > >   If we actually look at the call sites of
> > >   devm_request_threaded_irq() then the vast majority of them print more or
> > >   less lousy error messages. A quick grep/sed/awk/sort/uniq revealed
> > > 
> > >      519 messages total (there are probably more)
> > > 
> > >      352 unique messages
> > > 
> > >      323 unique messages after lower casing
> > > 
> > >          Those 323 are mostly just variants of the same patterns with
> > >          slight modifications in formatting and information provided.
> > > 
> > >      186 of these messages do not deliver any useful information,
> > >          e.g. "no irq", "
> > > 
> > >      The most useful one of all is: "could request wakeup irq: %d"
> > > 
> > >   So there is certainly an argument to be made that this particular
> > >   function should print a well formatted and informative error message.
> > > 
> > >   It's not a general allocator like kmalloc(). It's specialized and in the
> > >   vast majority of cases failing to request the interrupt causes the
> > >   device probe to fail. So having proper and consistent information why
> > >   the device cannot be used _is_ useful.
> > > 
> > > Let's use devm_request_threaded_irq_emsg(), which ensure that all error
> > > handling branches print error information. In this way, when this function
> > > fails, the upper-layer functions can directly return an error code without
> > > missing debugging information. Otherwise, the error message will be
> > > printed redundantly or missing.
> > > 
> > > Cc: Thomas Gleixner <tglx@linutronix.de>
> > > Signed-off-by: Yangtao Li <frank.li@vivo.com>
> > > ---
> > >  drivers/thermal/armada_thermal.c | 13 +++++--------
> > >  1 file changed, 5 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
> > > index 9f6dc4fc9112..a5e140643f00 100644
> > > --- a/drivers/thermal/armada_thermal.c
> > > +++ b/drivers/thermal/armada_thermal.c
> > > @@ -913,15 +913,12 @@ static int armada_thermal_probe(struct platform_device *pdev)
> > >  
> > >  	/* The overheat interrupt feature is not mandatory */
> > >  	if (irq > 0) {
> > > -		ret = devm_request_threaded_irq(&pdev->dev, irq,
> > > -						armada_overheat_isr,
> > > -						armada_overheat_isr_thread,
> > > -						0, NULL, priv);
> > > -		if (ret) {
> > > -			dev_err(&pdev->dev, "Cannot request threaded IRQ %d\n",
> > > -				irq);
> > > +		ret = devm_request_threaded_irq_emsg(&pdev->dev, irq,
> > > +						     armada_overheat_isr,
> > > +						     armada_overheat_isr_thread,
> > > +						     0, NULL, priv, NULL);
> > > +		if (ret)  
> > 
> > I don't see a patch renaming this helper with s/emsg//, do you plan to
> > keep it like that? I bet nobody outside of this series will notice the
> > new helper and will continue to add error messages because it kind
> > of feels "right" to do so.
> > 
> > I would rather prefer returning to the original function name which
> > everybody knows/uses.  
> 
> See https://lore.kernel.org/lkml/87h6qpyzkd.ffs@tglx for why there is a
> new function name.

Yes of course, I fully understand Thomas' concerns, but I am
questioning the usefulness of creating such helper if it's not the
default. People will continue to use [devm_]request_threaded_irq()
without noticing the new helper. If we want to make this change useful,
I believe we should:
- target all users
- at the end of the series: atomically include the error message in
  request_threaded_irq() and rename all callers of the _verbose variant
  which will eventually vanish.

Otherwise this is a lot of noise for very little progress, IMHO :)

Thanks,
Miquèl
diff mbox series

Patch

diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
index 9f6dc4fc9112..a5e140643f00 100644
--- a/drivers/thermal/armada_thermal.c
+++ b/drivers/thermal/armada_thermal.c
@@ -913,15 +913,12 @@  static int armada_thermal_probe(struct platform_device *pdev)
 
 	/* The overheat interrupt feature is not mandatory */
 	if (irq > 0) {
-		ret = devm_request_threaded_irq(&pdev->dev, irq,
-						armada_overheat_isr,
-						armada_overheat_isr_thread,
-						0, NULL, priv);
-		if (ret) {
-			dev_err(&pdev->dev, "Cannot request threaded IRQ %d\n",
-				irq);
+		ret = devm_request_threaded_irq_emsg(&pdev->dev, irq,
+						     armada_overheat_isr,
+						     armada_overheat_isr_thread,
+						     0, NULL, priv, NULL);
+		if (ret)
 			return ret;
-		}
 	}
 
 	/*