Re: [Qemu-devel] [PULL 54/61] blockdev: Remove IF_* check for read-only blockdev_init

[Stefan Weil <sw@weilnetz.de>]

Am 11.10.2013 17:05, schrieb Kevin Wolf:
> IF_NONE allows read-only, which makes forbidding it in this place
> for other types pretty much pointless.
>
> Instead, make sure that all devices for which the check would have
> errored out check in their init function that they don't get a read-only
> BlockDriverState. This catches even cases where IF_NONE and -device is
> used.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> ---
>

This patch breaks current QEMU (SIGSEGV with ARM in several test scenarios):

$ git bisect bad
4f8a066b5fc254eeaabbbde56ba4f5b29cc68fdf is the first bad commit
commit 4f8a066b5fc254eeaabbbde56ba4f5b29cc68fdf
Author: Kevin Wolf <kwolf@redhat.com>
Date:   Fri Sep 13 15:51:47 2013 +0200

    blockdev: Remove IF_* check for read-only blockdev_init
[...]

See the gdb protocol below for more details (Linux x86_64 host, default
configuration).

I got a bug report from a Windows user, but the crash is not OS specific.

Regards,
Stefan


(gdb) r
Starting program: bin/arm-softmmu/qemu-system-arm -M versatilepb -L
pc-bios -kernel vmlinuz-2.6.32-5-versatile -initrd
initrd.img-2.6.32-5-versatile -sd debian_squeeze_armel_standard.qcow2
-append root=/dev/sda1
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Breakpoint 5, pl181_init (sbd=0x5555565d3020) at hw/sd/pl181.c:482
482     {
(gdb) i s
#0  pl181_init (sbd=0x5555565d3020) at hw/sd/pl181.c:482
#1  0x00005555556d10e8 in sysbus_device_init (dev=0x5555565d3020) at
hw/core/sysbus.c:143
#2  0x00005555556ce6d3 in device_realize (dev=0x5555565d3020,
err=0x7fffffffdb08) at hw/core/qdev.c:178
#3  0x00005555556d002a in device_set_realized (obj=0x5555565d3020,
value=true, err=0x7fffffffdc80) at hw/core/qdev.c:699
#4  0x0000555555849520 in property_set_bool (obj=0x5555565d3020,
v=0x5555565d54d0, opaque=0x5555565ca870, name=0x555555a3c186 "realized",
errp=0x7fffffffdc80) at qom/object.c:1315
#5  0x0000555555848065 in object_property_set (obj=0x5555565d3020,
v=0x5555565d54d0, name=0x555555a3c186 "realized", errp=0x7fffffffdc80)
at qom/object.c:803
#6  0x00005555558497ca in object_property_set_qobject
(obj=0x5555565d3020, value=0x5555565adc20, name=0x555555a3c186
"realized", errp=0x7fffffffdc80) at qom/qom-qobject.c:24
#7  0x0000555555848351 in object_property_set_bool (obj=0x5555565d3020,
value=true, name=0x555555a3c186 "realized", errp=0x7fffffffdc80) at
qom/object.c:866
#8  0x00005555556ce60f in qdev_init (dev=0x5555565d3020) at
hw/core/qdev.c:163
#9  0x00005555556ceb8e in qdev_init_nofail (dev=0x5555565d3020) at
hw/core/qdev.c:277
#10 0x00005555556d11c3 in sysbus_create_varargs (name=0x555555a87f74
"pl181", addr=268455936) at hw/core/sysbus.c:157
#11 0x0000555555901572 in versatile_init (args=0x7fffffffe2d0,
board_id=387) at hw/arm/versatilepb.c:284
#12 0x0000555555901835 in vpb_init (args=0x7fffffffe2d0) at
hw/arm/versatilepb.c:357
#13 0x000055555589a38b in main (argc=13, argv=0x7fffffffe508,
envp=0x7fffffffe578) at vl.c:4245
(gdb) c
Continuing.

Breakpoint 5, pl181_init (sbd=0x5555565deda0) at hw/sd/pl181.c:482
482     {
(gdb)
Continuing.

Program received signal SIGSEGV, Segmentation fault.
0x000055555560b25f in bdrv_is_read_only (bs=0x0) at block.c:2933
2933        return bs->read_only;
(gdb) i s
#0  0x000055555560b25f in bdrv_is_read_only (bs=0x0) at block.c:2933
#1  0x0000555555794220 in sd_init (bs=0x0, is_spi=false) at hw/sd/sd.c:497
#2  0x000055555579316e in pl181_init (sbd=0x5555565deda0) at
hw/sd/pl181.c:493
#3  0x00005555556d10e8 in sysbus_device_init (dev=0x5555565deda0) at
hw/core/sysbus.c:143
#4  0x00005555556ce6d3 in device_realize (dev=0x5555565deda0,
err=0x7fffffffdb08) at hw/core/qdev.c:178
#5  0x00005555556d002a in device_set_realized (obj=0x5555565deda0,
value=true, err=0x7fffffffdc80) at hw/core/qdev.c:699
#6  0x0000555555849520 in property_set_bool (obj=0x5555565deda0,
v=0x5555565e1250, opaque=0x5555565ca500, name=0x555555a3c186 "realized",
errp=0x7fffffffdc80) at qom/object.c:1315
#7  0x0000555555848065 in object_property_set (obj=0x5555565deda0,
v=0x5555565e1250, name=0x555555a3c186 "realized", errp=0x7fffffffdc80)
at qom/object.c:803
#8  0x00005555558497ca in object_property_set_qobject
(obj=0x5555565deda0, value=0x5555565ca5f0, name=0x555555a3c186
"realized", errp=0x7fffffffdc80) at qom/qom-qobject.c:24
#9  0x0000555555848351 in object_property_set_bool (obj=0x5555565deda0,
value=true, name=0x555555a3c186 "realized", errp=0x7fffffffdc80) at
qom/object.c:866
#10 0x00005555556ce60f in qdev_init (dev=0x5555565deda0) at
hw/core/qdev.c:163
#11 0x00005555556ceb8e in qdev_init_nofail (dev=0x5555565deda0) at
hw/core/qdev.c:277
#12 0x00005555556d11c3 in sysbus_create_varargs (name=0x555555a87f74
"pl181", addr=268480512) at hw/core/sysbus.c:157
#13 0x000055555590159f in versatile_init (args=0x7fffffffe2d0,
board_id=387) at hw/arm/versatilepb.c:285
#14 0x0000555555901835 in vpb_init (args=0x7fffffffe2d0) at
hw/arm/versatilepb.c:357
#15 0x000055555589a38b in main (argc=13, argv=0x7fffffffe508,
envp=0x7fffffffe578) at vl.c:4245