On Wed, Feb 27, 2013 at 09:41:41AM -0800, Ben Pfaff wrote:
> On Wed, Feb 27, 2013 at 04:12:16PM +0900, Simon Horman wrote:
> > ofpbuf_put_* may reallocate the underlying buffer of the ofpbuf and
> > thus writing data after a ofpbuf_put_* call must write to memory
> > relative to the pointer returned by the call.
> >
> > Prior to this change the length and trailing value would not be written to
> > the set_field action if ofpbuf_put_* may reallocated the underlying buffer.
> >
> > Also make use of ofpbuf_put_zero() to avoid calling memset() directly.
> >
> > Signed-off-by: Simon Horman <ho...@verge.net.au>
>
> Good catch!
>
> I think that we don't really need to reload oasf at all, because we
> can just initialize oasf->len earlier and then not refer back to oasf
> again after the ofpbuf_put(). That seems a little nicer. So how
> about this:
Indeed it does, how silly of me not to notice that.
I have verified the patch below passes the test case I have which
is to add 120k flows and then run the following:
ovs-ofctl --protocols OpenFlow12 dump-flows br0
On the off chance that it is of value to you:
Tested-by: Simon Horman <ho...@verge.net.au>
> --8<--------------------------cut here-------------------------->8--
>
> From: Simon Horman <ho...@verge.net.au>
> Date: Wed, 27 Feb 2013 16:12:16 +0900
> Subject: [PATCH] nx-match: Correct writing of value and length in
> set_field_to_ofast()
>
> ofpbuf_put_* may reallocate the underlying buffer of the ofpbuf and
> thus writing data after a ofpbuf_put_* call must write to memory
> relative to the pointer returned by the call.
>
> Prior to this change the length and trailing value would not be written to
> the set_field action if ofpbuf_put_* may reallocated the underlying buffer.
>
> Also make use of ofpbuf_put_zero() to avoid calling memset() directly.
>
> Signed-off-by: Simon Horman <ho...@verge.net.au>
> Signed-off-by: Ben Pfaff <b...@nicira.com>
> ---
> lib/nx-match.c | 15 ++++++---------
> 1 files changed, 6 insertions(+), 9 deletions(-)
>
> diff --git a/lib/nx-match.c b/lib/nx-match.c
> index 4ff516e..e5545de 100644
> --- a/lib/nx-match.c
> +++ b/lib/nx-match.c
> @@ -1217,22 +1217,19 @@ set_field_to_ofast(const struct ofpact_reg_load *load,
> struct ofpbuf *openflow)
> {
> const struct mf_field *mf = load->dst.field;
> + uint16_t padded_value_len = ROUND_UP(mf->n_bytes, 8);
> struct ofp12_action_set_field *oasf;
> - uint16_t padded_value_len;
> -
> - oasf = ofputil_put_OFPAT12_SET_FIELD(openflow);
> - oasf->dst = htonl(mf->oxm_header);
> + char *value;
>
> /* Set field is the only action of variable length (so far),
> * so handling the variable length portion is open-coded here */
> - padded_value_len = ROUND_UP(mf->n_bytes, 8);
> - ofpbuf_put_uninit(openflow, padded_value_len);
> + oasf = ofputil_put_OFPAT12_SET_FIELD(openflow);
> + oasf->dst = htonl(mf->oxm_header);
> oasf->len = htons(ntohs(oasf->len) + padded_value_len);
> - memset(oasf + 1, 0, padded_value_len);
>
> + value = ofpbuf_put_zeros(openflow, padded_value_len);
> bitwise_copy(&load->subvalue, sizeof load->subvalue, load->dst.ofs,
> - oasf + 1, mf->n_bytes, load->dst.ofs, load->dst.n_bits);
> - return;
> + value, mf->n_bytes, load->dst.ofs, load->dst.n_bits);
> }
>
> void
> --
> 1.7.2.5
>
_______________________________________________
dev mailing list
dev@openvswitch.org
http://openvswitch.org/mailman/listinfo/dev
