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* [PATCH] staging: netlogic: Remove unnecessary error print
@ 2019-03-21  9:57 Himadri Pandya
  2019-03-21 10:08 ` [Outreachy kernel] " Julia Lawall
  0 siblings, 1 reply; 4+ messages in thread
From: Himadri Pandya @ 2019-03-21  9:57 UTC (permalink / raw)
  To: gregkh; +Cc: outreachy-kernel, Himadri Pandya

Kmalloc normally produces a backtrace when there is not enough memory.
So it is unnecessary to print an error message that provides only this
information. Hence, remove pr_error() from memory allocation check.
Issue found using Coccinelle.

Signed-off-by: Himadri Pandya <himadri18.07@gmail.com>
---
 drivers/staging/netlogic/xlr_net.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/staging/netlogic/xlr_net.c b/drivers/staging/netlogic/xlr_net.c
index 8554fcf4321b..afba1248e100 100644
--- a/drivers/staging/netlogic/xlr_net.c
+++ b/drivers/staging/netlogic/xlr_net.c
@@ -389,10 +389,8 @@ static void *xlr_config_spill(struct xlr_net_priv *priv, int reg_start_0,
 	base = priv->base_addr;
 	spill_size = size;
 	spill = kmalloc(spill_size + SMP_CACHE_BYTES, GFP_ATOMIC);
-	if (!spill) {
-		pr_err("Unable to allocate memory for spill area!\n");
+	if (!spill)
 		return ZERO_SIZE_PTR;
-	}
 
 	spill = PTR_ALIGN(spill, SMP_CACHE_BYTES);
 	phys_addr = virt_to_phys(spill);
-- 
2.17.1



^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [Outreachy kernel] [PATCH] staging: netlogic: Remove unnecessary error print
  2019-03-21  9:57 [PATCH] staging: netlogic: Remove unnecessary error print Himadri Pandya
@ 2019-03-21 10:08 ` Julia Lawall
  2019-03-21 10:40   ` Himadri Pandya
  0 siblings, 1 reply; 4+ messages in thread
From: Julia Lawall @ 2019-03-21 10:08 UTC (permalink / raw)
  To: Himadri Pandya; +Cc: gregkh, outreachy-kernel



On Thu, 21 Mar 2019, Himadri Pandya wrote:

> Kmalloc normally produces a backtrace when there is not enough memory.
> So it is unnecessary to print an error message that provides only this
> information. Hence, remove pr_error() from memory allocation check.
> Issue found using Coccinelle.
>
> Signed-off-by: Himadri Pandya <himadri18.07@gmail.com>
> ---
>  drivers/staging/netlogic/xlr_net.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/staging/netlogic/xlr_net.c b/drivers/staging/netlogic/xlr_net.c
> index 8554fcf4321b..afba1248e100 100644
> --- a/drivers/staging/netlogic/xlr_net.c
> +++ b/drivers/staging/netlogic/xlr_net.c
> @@ -389,10 +389,8 @@ static void *xlr_config_spill(struct xlr_net_priv *priv, int reg_start_0,
>  	base = priv->base_addr;
>  	spill_size = size;
>  	spill = kmalloc(spill_size + SMP_CACHE_BYTES, GFP_ATOMIC);
> -	if (!spill) {
> -		pr_err("Unable to allocate memory for spill area!\n");
> +	if (!spill)
>  		return ZERO_SIZE_PTR;

This seems to be the only driver that uses ZERO_SIZE_PTR as the result for
kmalloc.  It could be worth looking into what happens to this value
afterwards.

julia

> -	}
>
>  	spill = PTR_ALIGN(spill, SMP_CACHE_BYTES);
>  	phys_addr = virt_to_phys(spill);
> --
> 2.17.1
>
> --
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> To view this discussion on the web visit https://groups.google.com/d/msgid/outreachy-kernel/20190321095717.24155-1-himadri18.07%40gmail.com.
> For more options, visit https://groups.google.com/d/optout.
>


^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [Outreachy kernel] [PATCH] staging: netlogic: Remove unnecessary error print
  2019-03-21 10:08 ` [Outreachy kernel] " Julia Lawall
@ 2019-03-21 10:40   ` Himadri Pandya
  2019-03-21 10:42     ` Julia Lawall
  0 siblings, 1 reply; 4+ messages in thread
From: Himadri Pandya @ 2019-03-21 10:40 UTC (permalink / raw)
  To: Julia Lawall; +Cc: Greg KH, outreachy-kernel

[-- Attachment #1: Type: text/plain, Size: 2459 bytes --]

On Thu, Mar 21, 2019 at 3:38 PM Julia Lawall <julia.lawall@lip6.fr> wrote:

>
>
> On Thu, 21 Mar 2019, Himadri Pandya wrote:
>
> > Kmalloc normally produces a backtrace when there is not enough memory.
> > So it is unnecessary to print an error message that provides only this
> > information. Hence, remove pr_error() from memory allocation check.
> > Issue found using Coccinelle.
> >
> > Signed-off-by: Himadri Pandya <himadri18.07@gmail.com>
> > ---
> >  drivers/staging/netlogic/xlr_net.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/staging/netlogic/xlr_net.c
> b/drivers/staging/netlogic/xlr_net.c
> > index 8554fcf4321b..afba1248e100 100644
> > --- a/drivers/staging/netlogic/xlr_net.c
> > +++ b/drivers/staging/netlogic/xlr_net.c
> > @@ -389,10 +389,8 @@ static void *xlr_config_spill(struct xlr_net_priv
> *priv, int reg_start_0,
> >       base = priv->base_addr;
> >       spill_size = size;
> >       spill = kmalloc(spill_size + SMP_CACHE_BYTES, GFP_ATOMIC);
> > -     if (!spill) {
> > -             pr_err("Unable to allocate memory for spill area!\n");
> > +     if (!spill)
> >               return ZERO_SIZE_PTR;
>
> This seems to be the only driver that uses ZERO_SIZE_PTR as the result for
> kmalloc.  It could be worth looking into what happens to this value
> afterwards.
>
> julia
>

This is interesting. Later the pointer *spill* is aligned with
*SMP_CACHE_BYTE**S (which is defined using L1_CACHE_BYTES). * As per my
understanding, *xlr_config_spill() *returns ZERO_SIZE_PTR if *kmalloc()* cannot
allocate sufficient memory(equivalent to *spill_size*) as the return value
is being used to configure network accelerator's communication interface.

Please correct me if I am mistaken.

Thank you.

- Himadri


>
> > -     }
> >
> >       spill = PTR_ALIGN(spill, SMP_CACHE_BYTES);
> >       phys_addr = virt_to_phys(spill);
> > --
> > 2.17.1
> >
> > --
> > 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/20190321095717.24155-1-himadri18.07%40gmail.com
> .
> > For more options, visit https://groups.google.com/d/optout.
> >
>

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^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [Outreachy kernel] [PATCH] staging: netlogic: Remove unnecessary error print
  2019-03-21 10:40   ` Himadri Pandya
@ 2019-03-21 10:42     ` Julia Lawall
  0 siblings, 0 replies; 4+ messages in thread
From: Julia Lawall @ 2019-03-21 10:42 UTC (permalink / raw)
  To: Himadri Pandya; +Cc: Greg KH, outreachy-kernel

[-- Attachment #1: Type: text/plain, Size: 3664 bytes --]



On Thu, 21 Mar 2019, Himadri Pandya wrote:

>
>
> On Thu, Mar 21, 2019 at 3:38 PM Julia Lawall <julia.lawall@lip6.fr> wrote:
>
>
>       On Thu, 21 Mar 2019, Himadri Pandya wrote:
>
>       > Kmalloc normally produces a backtrace when there is not enough memory.
>       > So it is unnecessary to print an error message that provides only this
>       > information. Hence, remove pr_error() from memory allocation check.
>       > Issue found using Coccinelle.
>       >
>       > Signed-off-by: Himadri Pandya <himadri18.07@gmail.com>
>       > ---
>       >ￜ drivers/staging/netlogic/xlr_net.c | 4 +---
>       >ￜ 1 file changed, 1 insertion(+), 3 deletions(-)
>       >
>       > diff --git a/drivers/staging/netlogic/xlr_net.c b/drivers/staging/netlogic/xlr_net.c
>       > index 8554fcf4321b..afba1248e100 100644
>       > --- a/drivers/staging/netlogic/xlr_net.c
>       > +++ b/drivers/staging/netlogic/xlr_net.c
>       > @@ -389,10 +389,8 @@ static void *xlr_config_spill(struct xlr_net_priv *priv, int reg_start_0,
>       >ￜ ￜ ￜ ￜbase = priv->base_addr;
>       >ￜ ￜ ￜ ￜspill_size = size;
>       >ￜ ￜ ￜ ￜspill = kmalloc(spill_size + SMP_CACHE_BYTES, GFP_ATOMIC);
>       > -ￜ ￜ ￜif (!spill) {
>       > -ￜ ￜ ￜ ￜ ￜ ￜ ￜpr_err("Unable to allocate memory for spill area!\n");
>       > +ￜ ￜ ￜif (!spill)
>       >ￜ ￜ ￜ ￜ ￜ ￜ ￜ ￜreturn ZERO_SIZE_PTR;
>
>       This seems to be the only driver that uses ZERO_SIZE_PTR as the result for
>       kmalloc.ￜ It could be worth looking into what happens to this value
>       afterwards.
>
>       julia
>
>
> This is interesting. Later the pointer spillￜis aligned withￜSMP_CACHE_BYTES (which is defined using L1_CACHE_BYTES).ￜￜAs per my understanding,ￜxlr_config_spill() returns ZERO_SIZE_PTR if kmalloc()ￜcannot allocate sufficient
> memory(equivalent to spill_size) as the return value is being used to configure network accelerator's communication interface.

The questin is who is checking the return value and whether it is checked
in the right manner.  I looked quickly at the cal site, and it seemed that
the result as stored in a structure field with no checking,  But perhaps
some checking is done afterwards.

julia

>
> Please correct me if I am mistaken.
>
> Thank you.
>
> - Himadri
> ￜ
>
>       > -ￜ ￜ ￜ}
>       >
>       >ￜ ￜ ￜ ￜspill = PTR_ALIGN(spill, SMP_CACHE_BYTES);
>       >ￜ ￜ ￜ ￜphys_addr = virt_to_phys(spill);
>       > --
>       > 2.17.1
>       >
>       > --
>       > 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/20190321095717.24155-1-himadri18.07%40gmail.com.
>       > For more options, visit https://groups.google.com/d/optout.
>       >
>
> --
> 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/CAPnhUpaXwEBMFa_ukU9uauFuEaUojMju_kG%2BWHnJ9SQcAXrSpA%40mail.gmail.com.
> For more options, visit https://groups.google.com/d/optout.
>
>

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-03-21 10:43 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2019-03-21  9:57 [PATCH] staging: netlogic: Remove unnecessary error print Himadri Pandya
2019-03-21 10:08 ` [Outreachy kernel] " Julia Lawall
2019-03-21 10:40   ` Himadri Pandya
2019-03-21 10:42     ` Julia Lawall

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