dcb: Fix error reporting when accessing "dcb app"

(cherry picked from commit 53542a53ebd1e0388f45328c7cfd70bfa453e31a)

backport-dcb-Fix-error-reporting-when-accessing-dcb-app.patch

@@ -0,0 +1,86 @@
+From 1b5c7414a42a29d559af85022afebc307a2b9d12 Mon Sep 17 00:00:00 2001
+From: Petr Machata <petrm@nvidia.com>
+Date: Wed, 9 Feb 2022 15:41:40 +0100
+Subject: [PATCH] dcb: Fix error reporting when accessing "dcb app"
+
+Currently dcb decodes the response from "dcb app add" and "del" by
+interpreting the returned attribute as u8. But the value stored there is
+actually a negative errno value.
+
+Additionally, "dcb app" currently shows two sets of messages, one in
+dcb_set_attribute_attr_cb() where the issue is detected, and another as a
+result of error return from that function.
+
+The current state is as follows:
+
+	# dcb app add dev swp36 dscp-prio 20:2
+	Error when attempting to set attribute: Unknown error 239
+	Attribute write: No such file or directory
+
+Fix the "unknown error" issue by correctly decoding the attribute as i8 and
+negating it. Furthermore, set errno to that value, and let the top-level
+"attribute write" error message show the correct message.
+
+Initialize errno to 0 before the dcb_talk() dispatch, and make the error
+print conditional on errno != 0. This way the few error messages that are
+worth describing in the place where they are detected will not cause the
+second error message to be printed.
+
+The fixed reporting looks like this:
+
+	# dcb app add dev swp36 dscp-prio 20:2
+	Attribute write: File exists
+
+Reported-by: Maksym Yaremchuk <maksymy@nvidia.com>
+Signed-off-by: Petr Machata <petrm@nvidia.com>
+Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
+
+Reference: https://github.com/iproute2/iproute2/commit/1b5c7414a42a29d559af85022afebc307a2b9d12
+---
+ dcb/dcb.c | 12 ++++++++----
+ 1 file changed, 8 insertions(+), 4 deletions(-)
+
+diff --git a/dcb/dcb.c b/dcb/dcb.c
+index b7c2df54..8d75ab0a 100644
+--- a/dcb/dcb.c
++++ b/dcb/dcb.c
+@@ -106,7 +106,7 @@ static int dcb_set_attribute_attr_cb(const struct nlattr *attr, void *data)
+ {
+ 	struct dcb_set_attribute_response *resp = data;
+ 	uint16_t len;
+-	uint8_t err;
++	int8_t err;
+ 
+ 	if (mnl_attr_get_type(attr) != resp->response_attr)
+ 		return MNL_CB_OK;
+@@ -117,10 +117,12 @@ static int dcb_set_attribute_attr_cb(const struct nlattr *attr, void *data)
+ 		return MNL_CB_ERROR;
+ 	}
+ 
++	/* The attribute is formally u8, but actually an i8 containing a
++	 * negative errno value.
++	 */
+ 	err = mnl_attr_get_u8(attr);
+ 	if (err) {
+-		fprintf(stderr, "Error when attempting to set attribute: %s\n",
+-			strerror(err));
++		errno = -err;
+ 		return MNL_CB_ERROR;
+ 	}
+ 
+@@ -242,9 +244,11 @@ static int __dcb_set_attribute(struct dcb *dcb, int command, const char *dev,
+ 	if (ret)
+ 		return ret;
+ 
++	errno = 0;
+ 	ret = dcb_talk(dcb, nlh, dcb_set_attribute_cb, &resp);
+ 	if (ret) {
+-		perror("Attribute write");
++		if (errno)
++			perror("Attribute write");
+ 		return ret;
+ 	}
+ 	return 0;
+-- 
+2.43.0.windows.1
+

iproute.spec

@@ -2,7 +2,7 @@
 Name:		iproute
 Version:	5.15.0
 Epoch:      1
-Release:	20
+Release:	21
 Summary:	Linux network configuration utilities
 License:	GPLv2+ and Public Domain
 URL:		https://kernel.org/pub/linux/utils/net/iproute2/
@@ -75,6 +75,7 @@ Patch9000:      feature-iproute-add-support-for-ipvlan-l2e-mode.patch
 Patch9001:      bugfix-iproute2-cancel-some-test-cases.patch
 Patch9002:      feature-iproute2-supports-to-parse-UB-device-and-related-display-of-vf-address.patch
 Patch9003:      sync-ipvlan_mode-enum-with-kernel-headers.patch
+Patch9004:      backport-dcb-Fix-error-reporting-when-accessing-dcb-app.patch
 
 BuildRequires:	gcc bison elfutils-libelf-devel flex iptables-devel
 BuildRequires:  libmnl-devel libselinux-devel pkgconfig libbpf-devel sudo make
@@ -150,6 +151,12 @@ install -m 0644 lib/libnetlink.a %{buildroot}%{_libdir}/libnetlink.a
 %{_mandir}/*
 
 %changelog
+* Wed Oct 09 2024 liningjie <liningjie@xfusion.com> - 1:5.15.0-21
+- Type:bugfix
+- ID:NA
+- SUG:NA
+- DESC:dcb: Fix error reporting when accessing "dcb app"
+
 * Fri Jul 26 2024 caokeming <caokeming@huawei.com> - 1:5.15.0-20
 - Type:bugfix
 - ID:NA