Re: [ovs-dev] [PATCH] compat: Fix broken partial backport of extack op parameter

[Gregory Rose]

On 4/14/2020 9:52 AM, Greg Rose wrote:

A series of commits added support for the extended ack
parameter to the newlink, changelink and validate ops in
the rtnl_link_ops structure:
a8b8a889e369d ("net: add netlink_ext_ack argument to rtnl_link_ops.validate")
7a3f4a185169b ("net: add netlink_ext_ack argument to rtnl_link_ops.newlink")
ad744b223c521 ("net: add netlink_ext_ack argument to rtnl_link_ops.changelink")

These commits were all added at the same time and present since the
Linux kernel 4.13 release. In our compatiblity layer we have a
define HAVE_EXT_ACK_IN_RTNL_LINKOPS that indicates the presence of
the extended ack parameter for these three link operations.

At least one distro has only backported two of the three patches,
for newlink and changelink, while not backporting patch a8b8a889e369d
for the validate op.  Our compatibility layer code in acinclude.m4
is able to find the presence of the extack within the rtnl_link_ops
structure so it defines HAVE_EXT_ACK_IN_RTNL_LINKOPS but since the
validate link op does not have the extack parameter the compilation
fails on recent kernels for that particular distro. Other kernel
distributions based upon this distro will presumably also encounter
the compile errors.

Introduce a new function in acinclude.m4 that will find function
op definitions and then search for the required parameter.  Then
use this function to define HAVE_RTNLOP_VALIDATE_WITH_EXTACK so
that we can detect and enable correct compilation on kernels
which have not backported the entire set of patches.  This function
is generic to any function op - it need not be in a structure.

In places where HAVE_EXT_ACK_IN_RTNL_LINKOPS wraps validate functions
replace it with the new HAVE_RTNLOP_VALIDATE_WITH_EXTACK define.

Passes Travis here:
https://travis-ci.org/github/gvrose8192/ovs-experimental/builds/674599698

Passes a kernel check-kmod test on several systems, including
sles12 sp4 4.12.14-95.48-default kernel, without any regressions.

Signed-off-by: Greg Rose <gvrose8...@gmail.com>
---
  acinclude.m4                       | 34 ++++++++++++++++++++++++++++++++++
  datapath/linux/compat/geneve.c     |  2 +-
  datapath/linux/compat/ip6_gre.c    | 10 +++++-----
  datapath/linux/compat/ip6_tunnel.c |  2 +-
  datapath/linux/compat/ip_gre.c     | 10 +++++-----
  datapath/linux/compat/lisp.c       |  2 +-
  datapath/linux/compat/stt.c        |  2 +-
  datapath/linux/compat/vxlan.c      |  2 +-
  8 files changed, 49 insertions(+), 15 deletions(-)

diff --git a/acinclude.m4 b/acinclude.m4
index 02efea6..1089f41 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -520,6 +520,37 @@ AC_DEFUN([OVS_FIND_PARAM_IFELSE], [
    fi
  ])

+dnl OVS_FIND_OP_PARAM_IFELSE(FILE, OP, REGEX, [IF-MATCH], [IF-NO-MATCH])

+dnl
+dnl Looks for OP in FILE. If it is found, greps for REGEX within the
+dnl OP definition. If this is successful, runs IF-MATCH, otherwise
+dnl IF_NO_MATCH. If IF-MATCH is empty then it defines to
+dnl OVS_DEFINE(HAVE_<OP>_WITH_<REGEX>), with <STRUCTURE> and <REGEX>

I was just looking at this again because I forgot to include the VMware
BZ # and then I noticed that <STRUCTURE> doesn't belong here either.

V2 forthcoming, please ignore this one.

- Greg

+dnl translated to uppercase.
+AC_DEFUN([OVS_FIND_OP_PARAM_IFELSE], [
+  AC_MSG_CHECKING([whether $2 has member $3 in $1])
+  if test -f $1; then
+    awk '/$2[[ \t\n]]*\)\(/,/;/' $1 2>/dev/null | grep '$3' >/dev/null
+    status=$?
+    case $status in
+      0)
+        AC_MSG_RESULT([yes])
+        m4_if([$4], [], 
[OVS_DEFINE([HAVE_]m4_toupper([$2])[_WITH_]m4_toupper([$3]))], [$4])
+        ;;
+      1)
+        AC_MSG_RESULT([no])
+        $5
+        ;;
+      *)
+        AC_MSG_ERROR([grep exited with status $status])
+        ;;
+    esac
+  else
+    AC_MSG_RESULT([file not found])
+    $5
+  fi
+])
+
  dnl OVS_DEFINE(NAME)
  dnl
  dnl Defines NAME to 1 in kcompat.h.
@@ -1056,6 +1087,9 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
    OVS_GREP_IFELSE([$KSRC/include/net/netlink.h],
                    [nla_parse_deprecated_strict],
                    [OVS_DEFINE([HAVE_NLA_PARSE_DEPRECATED_STRICT])])
+  OVS_FIND_OP_PARAM_IFELSE([$KSRC/include/net/rtnetlink.h],
+                           [validate], [extack],
+                           [OVS_DEFINE([HAVE_RTNLOP_VALIDATE_WITH_EXTACK])])

if cmp -s datapath/linux/kcompat.h.new \

              datapath/linux/kcompat.h >/dev/null 2>&1; then
diff --git a/datapath/linux/compat/geneve.c b/datapath/linux/compat/geneve.c
index 5b18396..1551a37 100644
--- a/datapath/linux/compat/geneve.c
+++ b/datapath/linux/compat/geneve.c
@@ -1419,7 +1419,7 @@ static const struct nla_policy 
geneve_policy[IFLA_GENEVE_MAX + 1] = {
        [IFLA_GENEVE_UDP_ZERO_CSUM6_RX] = { .type = NLA_U8 },
  };

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef  HAVE_RTNLOP_VALIDATE_WITH_EXTACK
  static int geneve_validate(struct nlattr *tb[], struct nlattr *data[],
                           struct netlink_ext_ack *extack)
  #else
diff --git a/datapath/linux/compat/ip6_gre.c b/datapath/linux/compat/ip6_gre.c
index da0fa43..3aa9844 100644
--- a/datapath/linux/compat/ip6_gre.c
+++ b/datapath/linux/compat/ip6_gre.c
@@ -1687,7 +1687,7 @@ static struct pernet_operations ip6gre_net_ops = {
        .id   = &ip6gre_net_id,
        .size = sizeof(struct ip6gre_net),
  };
-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS
+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
  static int rpl_ip6gre_tunnel_validate(struct nlattr *tb[],
                                      struct nlattr *data[],
                                      struct netlink_ext_ack *extack)
@@ -1713,7 +1713,7 @@ static int rpl_ip6gre_tunnel_validate(struct nlattr *tb[],
  }
  #define ip6gre_tunnel_validate rpl_ip6gre_tunnel_validate

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
  static int rpl_ip6gre_tap_validate(struct nlattr *tb[], struct nlattr *data[],
                                   struct netlink_ext_ack *extack)
  #else
@@ -1739,7 +1739,7 @@ static int rpl_ip6gre_tap_validate(struct nlattr *tb[], 
struct nlattr *data[])
        }

out:

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS
+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
        return ip6gre_tunnel_validate(tb, data, extack);
  #else
        return ip6gre_tunnel_validate(tb, data);
@@ -1747,7 +1747,7 @@ out:
  }
  #define ip6gre_tap_validate rpl_ip6gre_tap_validate

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
  static int rpl_ip6erspan_tap_validate(struct nlattr *tb[],
                                      struct nlattr *data[],
                                      struct netlink_ext_ack *extack)
@@ -1762,7 +1762,7 @@ static int rpl_ip6erspan_tap_validate(struct nlattr *tb[],
        if (!data)
                return 0;

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
        ret = ip6gre_tap_validate(tb, data, extack);
  #else
        ret = ip6gre_tap_validate(tb, data);
diff --git a/datapath/linux/compat/ip6_tunnel.c 
b/datapath/linux/compat/ip6_tunnel.c
index 9f4bae7..984a51b 100644
--- a/datapath/linux/compat/ip6_tunnel.c
+++ b/datapath/linux/compat/ip6_tunnel.c
@@ -1754,7 +1754,7 @@ static int __net_init ip6_fb_tnl_dev_init(struct 
net_device *dev)
        return 0;
  }

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
  static int rpl_ip6_tnl_validate(struct nlattr *tb[], struct nlattr *data[],
                                struct netlink_ext_ack *extack)
  #else
diff --git a/datapath/linux/compat/ip_gre.c b/datapath/linux/compat/ip_gre.c
index 41379b1..c194ffe 100644
--- a/datapath/linux/compat/ip_gre.c
+++ b/datapath/linux/compat/ip_gre.c
@@ -623,7 +623,7 @@ static const struct gre_protocol ipgre_protocol = {
        .err_handler = __gre_err,
  };

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
  static int ipgre_tunnel_validate(struct nlattr *tb[], struct nlattr *data[],
                                 struct netlink_ext_ack *extack)
  #else
@@ -646,7 +646,7 @@ static int ipgre_tunnel_validate(struct nlattr *tb[], 
struct nlattr *data[])
        return 0;
  }

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
  static int ipgre_tap_validate(struct nlattr *tb[], struct nlattr *data[],
                              struct netlink_ext_ack *extack)
  #else
@@ -672,7 +672,7 @@ static int ipgre_tap_validate(struct nlattr *tb[], struct 
nlattr *data[])
        }

out:

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS
+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
        return ipgre_tunnel_validate(tb, data, NULL);
  #else
        return ipgre_tunnel_validate(tb, data);
@@ -707,7 +707,7 @@ enum {

#define RPL_IFLA_GRE_MAX (IFLA_GRE_ERSPAN_HWID + 1) -#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
  static int erspan_validate(struct nlattr *tb[], struct nlattr *data[],
                           struct netlink_ext_ack *extack)
  #else
@@ -720,7 +720,7 @@ static int erspan_validate(struct nlattr *tb[], struct 
nlattr *data[])
        if (!data)
                return 0;

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
        ret = ipgre_tap_validate(tb, data, NULL);
  #else
        ret = ipgre_tap_validate(tb, data);
diff --git a/datapath/linux/compat/lisp.c b/datapath/linux/compat/lisp.c
index 58144ad..6dc066d 100644
--- a/datapath/linux/compat/lisp.c
+++ b/datapath/linux/compat/lisp.c
@@ -612,7 +612,7 @@ static const struct nla_policy lisp_policy[IFLA_LISP_MAX + 
1] = {
        [IFLA_LISP_PORT]              = { .type = NLA_U16 },
  };

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
  static int lisp_validate(struct nlattr *tb[], struct nlattr *data[],
                         struct netlink_ext_ack __always_unused *extack)
  #else
diff --git a/datapath/linux/compat/stt.c b/datapath/linux/compat/stt.c
index 8a5853f..39a2947 100644
--- a/datapath/linux/compat/stt.c
+++ b/datapath/linux/compat/stt.c
@@ -1904,7 +1904,7 @@ static const struct nla_policy stt_policy[IFLA_STT_MAX + 
1] = {
        [IFLA_STT_PORT]              = { .type = NLA_U16 },
  };

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
  static int stt_validate(struct nlattr *tb[], struct nlattr *data[],
                        struct netlink_ext_ack __always_unused *extack)
  #else
diff --git a/datapath/linux/compat/vxlan.c b/datapath/linux/compat/vxlan.c
index 6090f42..f8f667e 100644
--- a/datapath/linux/compat/vxlan.c
+++ b/datapath/linux/compat/vxlan.c
@@ -1708,7 +1708,7 @@ static const struct nla_policy 
vxlan_policy[IFLA_VXLAN_MAX + 1] = {
        [IFLA_VXLAN_REMCSUM_NOPARTIAL]  = { .type = NLA_FLAG },
  };

-#ifdef HAVE_EXT_ACK_IN_RTNL_LINKOPS

+#ifdef HAVE_RTNLOP_VALIDATE_WITH_EXTACK
  static int vxlan_validate(struct nlattr *tb[], struct nlattr *data[],
                          struct netlink_ext_ack *extack)
  #else

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