Re: [PATCH 2/5] mm: remove unlikly NULL from kfree
From: Pekka Enberg
Date: Wed Mar 25 2009 - 03:34:42 EST
On Wed, Mar 25, 2009 at 7:19 AM, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> From: Steven Rostedt <rostedt@xxxxxxxxxxx>
>
> Impact: clean up
>
> A NULL pointer to kfree is no longer unlikely, as seen by the
> annotated branch profiler:
>
> correct incorrect % Function File Line
> ------- --------- - -------- ---- ----
> 728571 1315540 64 kfree slab.c 3719
>
> This makes sense, since we now encourage developers to just call kfree
> without checking for NULL.
But those are _error handling paths_ (at least supposed to be). I
wonder which call-sites are responsible for this. Can frtrace help us
here?
> ---
> mm/slab.c | 2 +-
> mm/slob.c | 2 +-
> mm/slub.c | 2 +-
> 3 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/slab.c b/mm/slab.c
> index 4d00855..0386c33 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -3716,7 +3716,7 @@ void kfree(const void *objp)
> struct kmem_cache *c;
> unsigned long flags;
>
> - if (unlikely(ZERO_OR_NULL_PTR(objp)))
> + if (ZERO_OR_NULL_PTR(objp))
> return;
> local_irq_save(flags);
> kfree_debugcheck(objp);
> diff --git a/mm/slob.c b/mm/slob.c
> index 52bc8a2..e077174 100644
> --- a/mm/slob.c
> +++ b/mm/slob.c
> @@ -491,7 +491,7 @@ void kfree(const void *block)
> {
> struct slob_page *sp;
>
> - if (unlikely(ZERO_OR_NULL_PTR(block)))
> + if (ZERO_OR_NULL_PTR(block))
> return;
>
> sp = (struct slob_page *)virt_to_page(block);
> diff --git a/mm/slub.c b/mm/slub.c
> index 0280eee..65dc436 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2743,7 +2743,7 @@ void kfree(const void *x)
> struct page *page;
> void *object = (void *)x;
>
> - if (unlikely(ZERO_OR_NULL_PTR(x)))
> + if (ZERO_OR_NULL_PTR(x))
> return;
>
> page = virt_to_head_page(x);
> --
> 1.6.2
>
> --
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