From: "Lavigne, Jamie" <lavignen@amazon.com>
To: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v2] Correctly handle malloc_elem resize with padding
Date: Thu, 8 Jun 2017 19:07:42 +0000 [thread overview]
Message-ID: <1496948862726.3852@amazon.com> (raw)
In-Reply-To: <3b80fa21-3d3e-73ae-235b-7581db5e8670@intel.com>
Hi Sergio,
> Hi Jamie,
>
> On 31/05/2017 01:16, Jamie Lavigne wrote:
> > Currently when a malloc_elem is split after resizing, any padding
> > present in the elem is ignored. This causes the resized elem to be too
> > small when padding is present, and user data can overwrite the beginning
> > of the following malloc_elem.
> >
> > Solve this by including the size of the padding when computing where to
> > split the malloc_elem.
>
> Nice catch!
>
> Could you please rework commit format a bit:
> - Add 'mem:' as prefix in your patch title
> - I would mention in the title that this is a fix
> - Provide 'Fixes' line in commit message
Updated.
>
> > Signed-off-by: Jamie Lavigne <lavignen@amazon.com>
> > ---
> > lib/librte_eal/common/malloc_elem.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/librte_eal/common/malloc_elem.c b/lib/librte_eal/common/malloc_elem.c
> > index 42568e1..8766fa8 100644
> > --- a/lib/librte_eal/common/malloc_elem.c
> > +++ b/lib/librte_eal/common/malloc_elem.c
> > @@ -333,9 +333,11 @@ malloc_elem_resize(struct malloc_elem *elem, size_t size)
> > elem_free_list_remove(next);
> > join_elem(elem, next);
> >
> > - if (elem->size - new_size >= MIN_DATA_SIZE + MALLOC_ELEM_OVERHEAD){
> > + const size_t new_total_size = new_size + elem->pad;
> > +
> > + if (elem->size - new_total_size >= MIN_DATA_SIZE + MALLOC_ELEM_OVERHEAD) {
> > /* now we have a big block together. Lets cut it down a bit, by splitting */
> > - struct malloc_elem *split_pt = RTE_PTR_ADD(elem, new_size);
> > + struct malloc_elem *split_pt = RTE_PTR_ADD(elem, new_total_size);
> > split_pt = RTE_PTR_ALIGN_CEIL(split_pt, RTE_CACHE_LINE_SIZE);
> > split_elem(elem, split_pt);
> > malloc_elem_free_list_insert(split_pt);
>
> This indeed fixes the issue you have mentioned. I was thinking of the
> following fix instead:
> - Add elem->pad to new_size
> - Remove current_size var and instead use elem->size
>
> I think those changes should have the same result while removing a
> couple of vars from the function, which I hope would be easier to read.
>
> What do you think?
I like this. It looks equivalent to my solution, but simpler. I will post an updated patch.
Jamie
next prev parent reply other threads:[~2017-06-08 19:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-31 0:09 [dpdk-dev] [PATCH] " Jamie Lavigne
2017-05-31 0:16 ` [dpdk-dev] [PATCH v2] " Jamie Lavigne
2017-06-06 14:18 ` Sergio Gonzalez Monroy
2017-06-08 19:07 ` Lavigne, Jamie [this message]
2017-06-08 19:12 ` [dpdk-dev] [PATCH v3] mem: fix " Jamie Lavigne
2017-06-20 10:18 ` Sergio Gonzalez Monroy
2017-06-28 21:12 ` Thomas Monjalon
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