netdev - [PATCH v2 bpf-next 0/2] sockmap: fix sg api usage

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Message-Id: <20180330002100.5724-1-bhole_prashant_q7@lab.ntt.co.jp>
Date:   Fri, 30 Mar 2018 09:20:58 +0900
From:   Prashant Bhole <bhole_prashant_q7@....ntt.co.jp>
To:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        "David S . Miller" <davem@...emloft.net>
Cc:     Prashant Bhole <bhole_prashant_q7@....ntt.co.jp>,
        John Fastabend <john.fastabend@...il.com>,
        netdev@...r.kernel.org
Subject: [PATCH v2 bpf-next 0/2] sockmap: fix sg api usage

These patches fix sg api usage in sockmap. Previously sockmap didn't
use sg_init_table(), which caused hitting BUG_ON in sg api, when
CONFIG_DEBUG_SG is enabled

v1: added sg_init_table() calls wherever needed.

v2:
- Patch1 adds new helper function in sg api. sg_init_marker()
- Patch2 sg_init_marker() and sg_init_table() in appropriate places

Backgroud:
While reviewing v1, John Fastabend raised a valid point about
unnecessary memset in sg_init_table() because sockmap uses sg table
which embedded in a struct. As enclosing struct is zeroed out, there
is unnecessary memset in sg_init_table.

So Daniel Borkmann suggested to define another static inline function
in scatterlist.h which only initializes sg_magic. Also this function 
will be called from sg_init_table. From this suggestion I defined a
function sg_init_marker() which sets sg_magic and calls sg_mark_end()

Prashant Bhole (2):
  lib/scatterlist: add sg_init_marker() helper
  bpf: sockmap: initialize sg table entries properly

 include/linux/scatterlist.h | 18 ++++++++++++++++++
 kernel/bpf/sockmap.c        | 13 ++++++++-----
 lib/scatterlist.c           |  9 +--------
 3 files changed, 27 insertions(+), 13 deletions(-)

-- 
2.14.3