Re: [Outreachy kernel] [PATCH] staging: netlogic: Remove unnecessary error print

[Himadri Pandya <himadri18.07@gmail.com>]

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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
> >
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