[linux-yocto] [PATCH 4.18-rt] of: phandle_cache merge fixup for preempt-rt

[Bruce Ashfield]

Thanks Paul, this is now merged.

Bruce

On Thu, Mar 21, 2019 at 3:12 PM Paul Gortmaker
<paul.gortmaker at windriver.com> wrote:
>
> In yocto merge 5cc3fddf0e2a ("Merge branch 'v4.18/standard/base' into
> v4.18/standard/preempt-rt/base") there was a conflict between the
> backport of upstream b8a9ac1a5b99 ("of: of_node_get()/of_node_put() nodes
> held in phandle cache") and the rt-specific commit b75caf08b721 ("of:
> allocate / free phandle cache outside of the devtree_lock")
>
> Unfortunately the conflict resolution left a shadow variable introduced
> by the rt patch as undefined, resulting in:
>
> drivers/of/base.c:120:2: error: 'shadow' undeclared (first use in this function)
>   shadow = phandle_cache;
>   ^~~~~~
>
> drivers/of/base.c: In function 'of_populate_phandle_cache':
> drivers/of/base.c:182:7: warning: 'shadow' is used uninitialized in this function [-Wuninitialized]
>
> Here we create a merge fix-up that basically aligns the impacted code to
> match what is currently found in the 4.19-rt (as of v4.19.15-rt12).
>
> Reported-by: Yue Tao <Yue.Tao at windriver.com>
> Signed-off-by: Paul Gortmaker <paul.gortmaker at windriver.com>
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 904c7686f9d7..4a33ef482bcc 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -106,31 +106,34 @@ static u32 phandle_cache_mask;
>  /*
>   * Caller must hold devtree_lock.
>   */
> -static void __of_free_phandle_cache(void)
> +static struct device_node** __of_free_phandle_cache(void)
>  {
>         u32 cache_entries = phandle_cache_mask + 1;
>         u32 k;
> +       struct device_node **shadow;
>
>         if (!phandle_cache)
> -               return;
> +               return NULL;
>
>         for (k = 0; k < cache_entries; k++)
>                 of_node_put(phandle_cache[k]);
>
>         shadow = phandle_cache;
>         phandle_cache = NULL;
> +       return shadow;
>  }
>
>  int of_free_phandle_cache(void)
>  {
>         unsigned long flags;
> +       struct device_node **shadow;
>
>         raw_spin_lock_irqsave(&devtree_lock, flags);
>
> -       __of_free_phandle_cache();
> +       shadow = __of_free_phandle_cache();
>
>         raw_spin_unlock_irqrestore(&devtree_lock, flags);
> -
> +       kfree(shadow);
>         return 0;
>  }
>  #if !defined(CONFIG_MODULES)
> @@ -169,27 +172,24 @@ void of_populate_phandle_cache(void)
>
>         raw_spin_lock_irqsave(&devtree_lock, flags);
>
> -       __of_free_phandle_cache();
> +       shadow = __of_free_phandle_cache();
>
>         for_each_of_allnodes(np)
>                 if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL)
>                         phandles++;
>
> -       raw_spin_unlock_irqrestore(&devtree_lock, flags);
> -       kfree(shadow);
> -
>         if (!phandles)
> -               return;
> +               goto out;
> +       raw_spin_unlock_irqrestore(&devtree_lock, flags);
>
>         cache_entries = roundup_pow_of_two(phandles);
>         phandle_cache_mask = cache_entries - 1;
>
> -       shadow = kcalloc(cache_entries, sizeof(*phandle_cache), GFP_KERNEL);
> -
> -       if (!shadow)
> -               return;
> +       phandle_cache = kcalloc(cache_entries, sizeof(*phandle_cache),
> +                               GFP_ATOMIC);
>         raw_spin_lock_irqsave(&devtree_lock, flags);
> -       phandle_cache = shadow;
> +       if (!phandle_cache)
> +               goto out;
>
>         for_each_of_allnodes(np)
>                 if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL) {
> @@ -197,7 +197,9 @@ void of_populate_phandle_cache(void)
>                         phandle_cache[np->phandle & phandle_cache_mask] = np;
>                 }
>
> +out:
>         raw_spin_unlock_irqrestore(&devtree_lock, flags);
> +       kfree(shadow);
>  }
>
>  void __init of_core_init(void)
> --
> 2.7.4
>


-- 
- Thou shalt not follow the NULL pointer, for chaos and madness await
thee at its end
- "Use the force Harry" - Gandalf, Star Trek II