From 3ae59580a0db469c1de72d5c58266b08fb096056 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Fri, 12 Sep 2014 21:26:22 +0200 Subject: block: Keep DriveInfo alive until BlockDriverState dies MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If the BDS's refcnt > 0, drive_del() destroys the DriveInfo, but not the BDS. This can happen in three places: * Device model destruction during unplug: blockdev_auto_del() * Xen IDE unplug: pci_piix3_xen_ide_unplug() * drive_del command when no device model is attached: do_drive_del() The other callers of drive_del are on error paths where refcnt == 1. If the user somehow manages to plug in a device model using a BDS that has gone through drive_del(), the legacy configuration passed in DriveInfo doesn't reach the device model, and automatic deletion on unplug doesn't work. Worse, some device models such as scsi-disk crash when DriveInfo doesn't exist. This is theoretical; I didn't research an actual reproducer. The problem was introduced when we replaced DriveInfo reference counting by BDS reference counting in commit a94a3fa..fa510eb. Fix by keeping DriveInfo alive until its BDS dies. This affects qemu_drive_opts: now you can't reuse the same ID for new drive options until the BDS dies. Before, you could, but since the code always attempts to create a BDS with the same ID next, the enclosing operation "create a new drive" failed anyway. Different error path, same result. Unfortunately, the fix involves use of blockdev.c stuff from block.c, which is a layering violation. Fortunately, my forthcoming BlockBackend work will get rid of it again. Signed-off-by: Markus Armbruster Reviewed-by: Max Reitz Reviewed-by: Benoît Canet Signed-off-by: Kevin Wolf --- stubs/Makefile.objs | 1 + stubs/blockdev.c | 12 ++++++++++++ 2 files changed, 13 insertions(+) create mode 100644 stubs/blockdev.c (limited to 'stubs') diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs index 5e347d04bd..c0b1f6a320 100644 --- a/stubs/Makefile.objs +++ b/stubs/Makefile.objs @@ -1,5 +1,6 @@ stub-obj-y += arch-query-cpu-def.o stub-obj-y += bdrv-commit-all.o +stub-obj-y += blockdev.o stub-obj-y += chr-baum-init.o stub-obj-y += chr-msmouse.o stub-obj-y += chr-testdev.o diff --git a/stubs/blockdev.c b/stubs/blockdev.c new file mode 100644 index 0000000000..5d0a79c3a6 --- /dev/null +++ b/stubs/blockdev.c @@ -0,0 +1,12 @@ +#include +#include "sysemu/blockdev.h" + +DriveInfo *drive_get_by_blockdev(BlockDriverState *bs) +{ + return NULL; +} + +void drive_info_del(DriveInfo *dinfo) +{ + assert(!dinfo); +} -- cgit v1.2.1