From f4c935bfa5bd3e4f4856dfdf660be0fa50d42798 Mon Sep 17 00:00:00 2001
Message-Id: <f4c935bfa5bd3e4f4856dfdf660be0fa50d42798@dist-git>
From: =?UTF-8?q?J=C3=A1n=20Tomko?= <jtomko@redhat.com>
Date: Mon, 10 Feb 2020 17:05:54 +0100
Subject: [PATCH] qemu: preserve error on bandwidth rollback
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We call APIs that reset the error in the rollback code.
Preserve the error from the original call that failed.

This turns the boringly cryptic:
  error: Unable to set interface parameters
  error: An error occurred, but the cause is unknown
to the unexpectedly anarchist:
  error: internal error: Child process (/usr/sbin/tc filter add
  dev vnet1 parent ffff: protocol all u32 match u32 0 0 police
  rate 4294968kbps burst 4294968kb mtu 64kb drop flowid :1)
  unexpected exit status 1: Illegal "rate"
  Illegal "police"

Signed-off-by: Ján Tomko <jtomko@redhat.com>
Fixes: f02e21cb3379a41cd42f2d8116f2d10dabace83b
https://bugzilla.redhat.com/show_bug.cgi?id=1800505
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
(cherry picked from commit 457b0e74888f61b759e334d91479c258663835d5)
Signed-off-by: Ján Tomko <jtomko@redhat.com>
Message-Id: <a49ef696966d8b8ca28d298ffab16c3a77b1102a.1581350626.git.jtomko@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/qemu/qemu_driver.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 08f492fa24..af81c4a6e4 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -11642,6 +11642,9 @@ qemuDomainSetInterfaceParameters(virDomainPtr dom,
 
         if (virNetDevBandwidthSet(net->ifname, newBandwidth, false,
                                   !virDomainNetTypeSharesHostView(net)) < 0) {
+            virErrorPtr orig_err;
+
+            virErrorPreserveLast(&orig_err);
             ignore_value(virNetDevBandwidthSet(net->ifname,
                                                net->bandwidth,
                                                false,
@@ -11650,6 +11653,7 @@ qemuDomainSetInterfaceParameters(virDomainPtr dom,
                 ignore_value(virDomainNetBandwidthUpdate(net,
                                                          net->bandwidth));
             }
+            virErrorRestore(&orig_err);
             goto endjob;
         }
 
-- 
2.25.0