Hi Jakub,

On 06/09/23 3:45 am, Jakub Kicinski wrote:

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On Thu, 31 Aug 2023 16:15:23 +0530 Parthiban Veerasooran wrote:

quoted

Subject: [PATCH net-next] ethtool: plca: fix plca enable data type while parsing the value

Since this is a fix the subject should say net instead of net-next.
[PATCH net v2] for the next revision.

Sure, will correct it in the v2.

quoted

The ETHTOOL_A_PLCA_ENABLED data type is u8. But while parsing the
value from the attribute, nla_get_u32() is used in the plca_update_sint()
function instead of nla_get_u8(). So plca_cfg.enabled variable is updated
with some garbage value instead of 0 or 1 and always enables plca even
though plca is disabled through ethtool application. This bug has been
fixed by implementing plca_update_sint_from_u8() function which uses
nla_get_u8() function to extract the plca_cfg.enabled value and the
function plca_update_sint_from_u32() is used for extracting the other
values using nla_get_u32() function.

Hm, yes, that seems like the best of the available options.

quoted

Fixes: 8580e16c28f3 ("net/ethtool: add netlink interface for the PLCA RS")

Please make sure you CC all the people who signed off the commit under
Fixes. You missed pabeni@redhat.com and andrew@lunn.ch

Ah yes, will include them in the v2.

quoted

Signed-off-by: Parthiban Veerasooran <Parthiban.Veerasooran@microchip.com>
---
  net/ethtool/plca.c | 34 ++++++++++++++++++++++++----------
  1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/net/ethtool/plca.c b/net/ethtool/plca.c
index b238a1afe9ae..b4e80dd33590 100644
--- a/net/ethtool/plca.c
+++ b/net/ethtool/plca.c

@@ -21,8 +21,8 @@ struct plca_reply_data {
  #define PLCA_REPDATA(__reply_base) \
       container_of(__reply_base, struct plca_reply_data, base)

-static void plca_update_sint(int *dst, const struct nlattr *attr,
-                          bool *mod)
+static void plca_update_sint_from_u32(int *dst, const struct nlattr *attr,
+                                   bool *mod)
  {
       if (!attr)
               return;

@@ -31,6 +31,16 @@ static void plca_update_sint(int *dst, const struct nlattr *attr,
       *mod = true;
  }

+static void plca_update_sint_from_u8(int *dst, const struct nlattr *attr,
+                                  bool *mod)
+{
+     if (!attr)
+             return;
+
+     *dst = nla_get_u8(attr);
+     *mod = true;
+}
+
  // PLCA get configuration message ------------------------------------------- //

  const struct nla_policy ethnl_plca_get_cfg_policy[] = {

@@ -144,14 +154,18 @@ ethnl_set_plca(struct ethnl_req_info *req_info, struct genl_info *info)
               return -EOPNOTSUPP;

       memset(&plca_cfg, 0xff, sizeof(plca_cfg));
-     plca_update_sint(&plca_cfg.enabled, tb[ETHTOOL_A_PLCA_ENABLED], &mod);
-     plca_update_sint(&plca_cfg.node_id, tb[ETHTOOL_A_PLCA_NODE_ID], &mod);
-     plca_update_sint(&plca_cfg.node_cnt, tb[ETHTOOL_A_PLCA_NODE_CNT], &mod);
-     plca_update_sint(&plca_cfg.to_tmr, tb[ETHTOOL_A_PLCA_TO_TMR], &mod);
-     plca_update_sint(&plca_cfg.burst_cnt, tb[ETHTOOL_A_PLCA_BURST_CNT],
-                      &mod);
-     plca_update_sint(&plca_cfg.burst_tmr, tb[ETHTOOL_A_PLCA_BURST_TMR],
-                      &mod);
+     plca_update_sint_from_u8(&plca_cfg.enabled, tb[ETHTOOL_A_PLCA_ENABLED],
+                              &mod);
+     plca_update_sint_from_u32(&plca_cfg.node_id, tb[ETHTOOL_A_PLCA_NODE_ID],
+                               &mod);
+     plca_update_sint_from_u32(&plca_cfg.node_cnt,
+                               tb[ETHTOOL_A_PLCA_NODE_CNT], &mod);
+     plca_update_sint_from_u32(&plca_cfg.to_tmr, tb[ETHTOOL_A_PLCA_TO_TMR],
+                               &mod);
+     plca_update_sint_from_u32(&plca_cfg.burst_cnt,
+                               tb[ETHTOOL_A_PLCA_BURST_CNT], &mod);
+     plca_update_sint_from_u32(&plca_cfg.burst_tmr,
+                               tb[ETHTOOL_A_PLCA_BURST_TMR], &mod);

This looks error prone. We still need to maintain the types in multiple
places. How about we use the policy to decide the type? Something along
the lines of (untested):

Hmm ok, I compiled and tested your proposal. Below is the minor change 
oberved during compilation.

plca_update_sint(int *dst, struct nlattr **tb, u32 attrid, bool *mod)

Will prepare and send the v2 with this proposal.

Best Regards,
Parthiban V