From 48bf7ea81aa848027bad24f7e7791b503dff727d Mon Sep 17 00:00:00 2001
From: Alberto Garcia <berto@igalia.com>
Date: Fri, 10 Nov 2017 20:54:46 +0200
Subject: [PATCH] block: Check for inserted BlockDriverState in
blk_io_limits_disable()
When you set I/O limits using block_set_io_throttle or the command
line throttling.* options they are kept in the BlockBackend regardless
of whether a BlockDriverState is attached to the backend or not.
Therefore when removing the limits using blk_io_limits_disable() we
need to check if there's a BDS before attempting to drain it, else it
will crash QEMU. This can be reproduced very easily using HMP:
(qemu) drive_add 0 if=none,throttling.iops-total=5000
(qemu) drive_del none0
Reported-by: sochin jiang <sochin.jiang@huawei.com>
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 0d3a67ce8d948bb33e08672564714dcfb76a3d8c.1510339534.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
block/block-backend.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/block/block-backend.c b/block/block-backend.c
index ab75da32c9..df92a6280d 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1980,10 +1980,16 @@ void blk_set_io_limits(BlockBackend *blk, ThrottleConfig *cfg)
void blk_io_limits_disable(BlockBackend *blk)
{
- assert(blk->public.throttle_group_member.throttle_state);
- bdrv_drained_begin(blk_bs(blk));
- throttle_group_unregister_tgm(&blk->public.throttle_group_member);
- bdrv_drained_end(blk_bs(blk));
+ BlockDriverState *bs = blk_bs(blk);
+ ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
+ assert(tgm->throttle_state);
+ if (bs) {
+ bdrv_drained_begin(bs);
+ }
+ throttle_group_unregister_tgm(tgm);
+ if (bs) {
+ bdrv_drained_end(bs);
+ }
}
/* should be called before blk_set_io_limits if a limit is set */
--
2.30.2