From: Alberto Garcia Date: Fri, 10 Nov 2017 18:54:46 +0000 (+0200) Subject: block: Check for inserted BlockDriverState in blk_io_limits_disable() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=48bf7ea81aa848027bad24f7e7791b503dff727d;p=qemu.git 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 Signed-off-by: Alberto Garcia Reviewed-by: Max Reitz Message-id: 0d3a67ce8d948bb33e08672564714dcfb76a3d8c.1510339534.git.berto@igalia.com Signed-off-by: Stefan Hajnoczi --- 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 */