[bug report] x86/resctrl: Bring cbm_validate() into the resource structure

[bug report] x86/resctrl: Bring cbm_validate() into the resource structure

[Dan Carpenter]

Hello Babu Moger,

The patch a36c5ff560fb: "x86/resctrl: Bring cbm_validate() into the
resource structure" from Nov 21, 2018, leads to the following static
checker warning:

	arch/x86/kernel/cpu/resctrl/ctrlmondata.c:227 parse_cbm()
	error: uninitialized symbol 'cbm_val'.

arch/x86/kernel/cpu/resctrl/ctrlmondata.c
   201  int parse_cbm(struct rdt_parse_data *data, struct rdt_resource *r,
   202                struct rdt_domain *d)
   203  {
   204          struct rdtgroup *rdtgrp = data->rdtgrp;
   205          u32 cbm_val;
   206  
   207          if (d->have_new_ctrl) {
   208                  rdt_last_cmd_printf("Duplicate domain %d\n", d->id);
   209                  return -EINVAL;
   210          }
   211  
   212          /*
   213           * Cannot set up more than one pseudo-locked region in a cache
   214           * hierarchy.
   215           */
   216          if (rdtgrp->mode = RDT_MODE_PSEUDO_LOCKSETUP &&
   217              rdtgroup_pseudo_locked_in_hierarchy(d)) {
   218                  rdt_last_cmd_printf("Pseudo-locked region in hierarchy\n");
   219                  return -EINVAL;
   220          }
   221  
   222          if (r->cbm_validate && !r->cbm_validate(data->buf, &cbm_val, r))
                    ^^^^^^^^^^^^^^^
Assume this is NULL

   223                  return -EINVAL;
   224  
   225          if ((rdtgrp->mode = RDT_MODE_EXCLUSIVE ||
   226               rdtgrp->mode = RDT_MODE_SHAREABLE) &&
   227              rdtgroup_cbm_overlaps_pseudo_locked(d, cbm_val)) {
                                                           ^^^^^^^
Then this is where Smatch complains that it's uninitialized.

   228                  rdt_last_cmd_printf("CBM overlaps with pseudo-locked region\n");
   229                  return -EINVAL;
   230          }
   231  


regards,
dan carpenter

Re: [bug report] x86/resctrl: Bring cbm_validate() into the resource structure

[Moger, Babu]

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Re: [bug report] x86/resctrl: Bring cbm_validate() into the resource structure

[Dan Carpenter]

On Wed, Nov 28, 2018 at 03:21:22PM +0000, Moger, Babu wrote:
> Copying Boris,
> 
> Hi Dan, The following patch should help. Can you please confirm.
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 286c03bb14a7..5a1b544795cd 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -201,7 +201,7 @@ int parse_cbm(struct rdt_parse_data *data, struct
> rdt_resource *r,
>               struct rdt_domain *d)
>  {
>         struct rdtgroup *rdtgrp = data->rdtgrp;
> -       u32 cbm_val;
> +       u32 cbm_val = 0;
> 
>         if (d->have_new_ctrl) {
>                 rdt_last_cmd_printf("Duplicate domain %d\n", d->id);
> 

That obviously silences the uninitialized variable warning...  You know
the code better than I do, so presumably it is correct as well.  :)

regards,
dan carpenter

Re: [bug report] x86/resctrl: Bring cbm_validate() into the resource structure

[Moger, Babu]

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