[PATCH 2/2] ARM: dma-mapping: fix leak in consistent_init

[tixy@yxit.co.uk (Tixy)]

On Mon, 2012-02-20 at 21:42 +0530, Ajeet Yadav wrote:
> Hi Tixy,
> Thanks for review, so what do you suggest drop or improve the patch? 
> 
I would say drop the patch, unless the more experienced Linux hands here
think otherwise.

-- 
Tixy

> With Regards,
> Ajeet Yadav
> 
> On Feb 18, 2012 9:28 PM, "Tixy" <tixy@yxit.co.uk> wrote:
>         On Fri, 2012-02-17 at 18:39 +0530, Ajeet Yadav wrote:
>         > Although the error in this case is unlikely, but logically
>         > if error occurs then we leak memory.
>         >
>         > Signed-off-by: Ajeet Yadav <ajeet.yadav.77@gmail.com>
>         
>         If you want to fix all the memory leaks then the page tables
>         allocated
>         by pte_alloc_kernel() need freeing as well, (and the pud and
>         pmd
>         tables?).
>         
>         However, if we run out of memory this early in boot, then the
>         system is
>         unusable anyway and it doesn't seem worth adding the extra
>         code
>         complexity to avoid any of these memory leaks.
>         
>         --
>         Tixy
>         
>         > ---
>         >  arch/arm/mm/dma-mapping.c |   24 ++++++++++++------------
>         >  1 files changed, 12 insertions(+), 12 deletions(-)
>         >
>         > diff --git a/arch/arm/mm/dma-mapping.c
>         b/arch/arm/mm/dma-mapping.c
>         > index 04bfa76..b8cf062 100644
>         > --- a/arch/arm/mm/dma-mapping.c
>         > +++ b/arch/arm/mm/dma-mapping.c
>         > @@ -161,7 +161,6 @@ static struct arm_vmregion_head
>         consistent_head = {
>         >   */
>         >  static int __init consistent_init(void)
>         >  {
>         > -     int ret = 0;
>         >       pgd_t *pgd;
>         >       pud_t *pud;
>         >       pmd_t *pmd;
>         > @@ -171,7 +170,7 @@ static int __init consistent_init(void)
>         >       unsigned long num_ptes = (CONSISTENT_END - base) >>
>         PMD_SHIFT;
>         >
>         >       consistent_pte = kmalloc(num_ptes * sizeof(pte_t *),
>         GFP_KERNEL);
>         > -     if (!consistent_pte) {
>         > +     if (unlikely(!consistent_pte)) {
>         >               pr_err("%s: no memory\n", __func__);
>         >               return -ENOMEM;
>         >       }
>         > @@ -183,32 +182,33 @@ static int __init
>         consistent_init(void)
>         >               pgd = pgd_offset(&init_mm, base);
>         >
>         >               pud = pud_alloc(&init_mm, pgd, base);
>         > -             if (!pud) {
>         > +             if (unlikely(!pud)) {
>         >                       printk(KERN_ERR "%s: no pud tables\n",
>         __func__);
>         > -                     ret = -ENOMEM;
>         > -                     break;
>         > +                     goto err;
>         >               }
>         >
>         >               pmd = pmd_alloc(&init_mm, pud, base);
>         > -             if (!pmd) {
>         > +             if (unlikely(!pmd)) {
>         >                       printk(KERN_ERR "%s: no pmd tables\n",
>         __func__);
>         > -                     ret = -ENOMEM;
>         > -                     break;
>         > +                     goto err;
>         >               }
>         >               WARN_ON(!pmd_none(*pmd));
>         >
>         >               pte = pte_alloc_kernel(pmd, base);
>         > -             if (!pte) {
>         > +             if (unlikely(!pte)) {
>         >                       printk(KERN_ERR "%s: no pte tables\n",
>         __func__);
>         > -                     ret = -ENOMEM;
>         > -                     break;
>         > +                     goto err;
>         >               }
>         >
>         >               consistent_pte[i++] = pte;
>         >               base += PMD_SIZE;
>         >       } while (base < CONSISTENT_END);
>         >
>         > -     return ret;
>         > +     return 0;
>         > +err:
>         > +     kfree(consistent_pte);
>         > +     consistent_pte = NULL;
>         > +     return -ENOMEM;
>         >  }
>         >
>         >  core_initcall(consistent_init);
>         
>         
>