Re: [Qemu-devel] [PATCH] block: Fix qemu crash when using scsi-block

[Kevin Wolf <kwolf@redhat.com>]

Am 23.11.2017 um 18:05 hat Deepa Srinivasan geschrieben:
> blk_aio_prwv() now takes a void pointer and the coroutine functions
> have been modified to cast it into QEMUIOVector if needed. It does not
> use an union in BlkRwCo since this leads to code - blk_aio_prwv()
> would have to write to the void pointer member, but coroutines would
> sometimes read the QEMUIOVector member. Paolo also suggested not using
> a union.

I don't particularly like void pointers, but I guess it's fair enough.

> Note that a similar issue exists in
> blk_ioctl()/blk_ioctl_entry()/blk_prw() where blk_prw() always creates
> the QEMUIOVector even if blk_ioctl()/blk_ioctl_entry() does not need a
> QEMUIOVector. This will need to be fixed separately to keep it
> consistent with the AIO path.

I don't think there is an actual problem in the blk_ioctl() path because
the iov on the stack stays valid as long as the coroutine runs. AIO is
different because it returns before the coroutine has terminated.

Kevin