linux-kernel - [PATCH 5.7 62/79] devlink: ignore -EOPNOTSUPP errors on dumpit

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Message-Id: <20200810151815.301734997@linuxfoundation.org>
Date:   Mon, 10 Aug 2020 17:21:21 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
        Jiri Pirko <jiri@...lanox.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.7 62/79] devlink: ignore -EOPNOTSUPP errors on dumpit

From: Jakub Kicinski <kuba@...nel.org>

[ Upstream commit 82274d075536322368ce710b211c41c37c4740b9 ]

Number of .dumpit functions try to ignore -EOPNOTSUPP errors.
Recent change missed that, and started reporting all errors
but -EMSGSIZE back from dumps. This leads to situation like
this:

$ devlink dev info
devlink answers: Operation not supported

Dump should not report an error just because the last device
to be queried could not provide an answer.

To fix this and avoid similar confusion make sure we clear
err properly, and not leave it set to an error if we don't
terminate the iteration.

Fixes: c62c2cfb801b ("net: devlink: don't ignore errors during dumpit")
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Reviewed-by: Jiri Pirko <jiri@...lanox.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/core/devlink.c |   24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -1065,7 +1065,9 @@ static int devlink_nl_cmd_sb_pool_get_du
 						   devlink_sb,
 						   NETLINK_CB(cb->skb).portid,
 						   cb->nlh->nlmsg_seq);
-			if (err && err != -EOPNOTSUPP) {
+			if (err == -EOPNOTSUPP) {
+				err = 0;
+			} else if (err) {
 				mutex_unlock(&devlink->lock);
 				goto out;
 			}
@@ -1266,7 +1268,9 @@ static int devlink_nl_cmd_sb_port_pool_g
 							devlink, devlink_sb,
 							NETLINK_CB(cb->skb).portid,
 							cb->nlh->nlmsg_seq);
-			if (err && err != -EOPNOTSUPP) {
+			if (err == -EOPNOTSUPP) {
+				err = 0;
+			} else if (err) {
 				mutex_unlock(&devlink->lock);
 				goto out;
 			}
@@ -1498,7 +1502,9 @@ devlink_nl_cmd_sb_tc_pool_bind_get_dumpi
 							   devlink_sb,
 							   NETLINK_CB(cb->skb).portid,
 							   cb->nlh->nlmsg_seq);
-			if (err && err != -EOPNOTSUPP) {
+			if (err == -EOPNOTSUPP) {
+				err = 0;
+			} else if (err) {
 				mutex_unlock(&devlink->lock);
 				goto out;
 			}
@@ -3299,7 +3305,9 @@ static int devlink_nl_cmd_param_get_dump
 						    NETLINK_CB(cb->skb).portid,
 						    cb->nlh->nlmsg_seq,
 						    NLM_F_MULTI);
-			if (err && err != -EOPNOTSUPP) {
+			if (err == -EOPNOTSUPP) {
+				err = 0;
+			} else if (err) {
 				mutex_unlock(&devlink->lock);
 				goto out;
 			}
@@ -3569,7 +3577,9 @@ static int devlink_nl_cmd_port_param_get
 						NETLINK_CB(cb->skb).portid,
 						cb->nlh->nlmsg_seq,
 						NLM_F_MULTI);
-				if (err && err != -EOPNOTSUPP) {
+				if (err == -EOPNOTSUPP) {
+					err = 0;
+				} else if (err) {
 					mutex_unlock(&devlink->lock);
 					goto out;
 				}
@@ -4479,7 +4489,9 @@ static int devlink_nl_cmd_info_get_dumpi
 					   cb->nlh->nlmsg_seq, NLM_F_MULTI,
 					   cb->extack);
 		mutex_unlock(&devlink->lock);
-		if (err && err != -EOPNOTSUPP)
+		if (err == -EOPNOTSUPP)
+			err = 0;
+		else if (err)
 			break;
 		idx++;
 	}