vringh: Use wiov->used to check for read/write desc order

As __vringh_iov() traverses a descriptor chain, it populates
each descriptor entry into either read or write vring iov
and increments that iov's ->used member. So, as we iterate
over a descriptor chain, at any point, (riov/wriov)->used
value gives the number of descriptor enteries available,
which are to be read or written by the device. As all read
iovs must precede the write iovs, wiov->used should be zero
when we are traversing a read descriptor. Current code checks
for wiov->i, to figure out whether any previous entry in the
current descriptor chain was a write descriptor. However,
iov->i is only incremented, when these vring iovs are consumed,
at a later point, and remain 0 in __vringh_iov(). So, correct
the check for read and write descriptor order, to use
wiov->used.

Acked-by: Jason Wang <[email protected]>
Reviewed-by: Stefano Garzarella <[email protected]>
Signed-off-by: Neeraj Upadhyay <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Michael S. Tsirkin <[email protected]>

0 files changed, 0 insertions, 0 deletions