Re: [PATCH 2/5] mm/hmm: Clean up some coding style and comments

[Jason Gunthorpe]

On Mon, May 06, 2019 at 04:29:39PM -0700, rcampb...@nvidia.com wrote:
> @@ -924,6 +922,7 @@ int hmm_range_register(struct hmm_range *range,
>                      unsigned page_shift)
>  {
>       unsigned long mask = ((1UL << page_shift) - 1UL);
> +     struct hmm *hmm;
>  
>       range->valid = false;
>       range->hmm = NULL;

I was finishing these patches off and noticed that 'hmm' above is
never initialized.

I added the below to this patch:

diff --git a/mm/hmm.c b/mm/hmm.c
index 678873eb21930a..8e7403f081f44a 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -932,19 +932,20 @@ int hmm_range_register(struct hmm_range *range,
        range->start = start;
        range->end = end;
 
-       range->hmm = hmm_get_or_create(mm);
-       if (!range->hmm)
+       hmm = hmm_get_or_create(mm);
+       if (!hmm)
                return -EFAULT;
 
        /* Check if hmm_mm_destroy() was call. */
-       if (range->hmm->mm == NULL || range->hmm->dead) {
-               hmm_put(range->hmm);
+       if (hmm->mm == NULL || hmm->dead) {
+               hmm_put(hmm);
                return -EFAULT;
        }
 
        /* Initialize range to track CPU page table updates. */
-       mutex_lock(&range->hmm->lock);
+       mutex_lock(&hmm->lock);
 
+       range->hmm = hmm;
        list_add_rcu(&range->list, &hmm->ranges);
 
        /*

Which I think was the intent of adding the 'struct hmm *'. I prefer
this arrangement as it does not set an leave an invalid hmm pointer in
the range if there is a failure..

Most probably the later patches fixed this up?

Please confirm, thanks

Regards,
Jason