xen-block: Fix double qlist remove and request leak
Commit a31ca6801c02 ("qemu/queue.h: clear linked list pointers on
remove") revealed that a request was removed twice from a list, once
in xen_block_finish_request() and a second time in
xen_block_release_request() when both function are called from
xen_block_complete_aio(). But also, the `requests_inflight' counter is
decreased twice, and thus became negative.
This is a bug that was introduced in bfd0d6366043 ("xen-block: improve
response latency"), where a `finished' list was removed.
That commit also introduced a leak of request in xen_block_do_aio().
That function calls xen_block_finish_request() but the request is
never released after that.
To fix both issue, we do two changes:
- we squash finish_request() and release_request() together as we want
to remove a request from 'inflight' list to add it to 'freelist'.
- before releasing a request, we need to let the other end know the
result, thus we should call xen_block_send_response() before
releasing a request.
The first change fixes the double QLIST_REMOVE() as we remove the extra
call. The second change makes the leak go away because if we want to
call finish_request(), we need to call a function that does all of
finish, send response, and release.
Fixes: bfd0d6366043 ("xen-block: improve response latency")
Signed-off-by: Anthony PERARD <firstname.lastname@example.org>
Reviewed-by: Paul Durrant <email@example.com>
[mreitz: Amended commit message as per Paul's suggestions]
Signed-off-by: Max Reitz <firstname.lastname@example.org>
1 file changed