John Snow <js...@redhat.com> writes:
> The if_max_devs table as in the past been an immutable
> default that controls the mapping of index => (bus,unit)
> for all boards and all HBAs for each interface type.
>
> Since adding this mapping information to the HBA device
> itself is currently unwieldly from the perspective of
> retrieving this information at option parsing time
> (e.g, within drive_new), we consider the alternative
> of marking the if_max_devs table mutable so that
> later configuration and initialization can adjust the
> mapping at will, but only up until a drive is added,
> at which point the mapping is finalized.
>
> Signed-off-by: John Snow <js...@redhat.com>
> ---
> blockdev.c | 26 +++++++++++++++++++++++++-
> include/sysemu/blockdev.h | 2 ++
> 2 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/blockdev.c b/blockdev.c
> index 81398e7..9b05f1b 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -60,7 +60,7 @@ static const char *const if_name[IF_COUNT] = {
> [IF_XEN] = "xen",
> };
>
> -static const int if_max_devs[IF_COUNT] = {
> +static int if_max_devs[IF_COUNT] = {
> /*
> * Do not change these numbers! They govern how drive option
> * index maps to unit and bus. That mapping is ABI.
> @@ -79,6 +79,30 @@ static const int if_max_devs[IF_COUNT] = {
> [IF_SCSI] = 7,
> };
>
> +/**
> + * Boards may call this to offer board-by-board overrides
> + * of the default, global values.
> + */
> +void override_max_devs(BlockInterfaceType type, int max_devs)
> +{
> + DriveInfo *dinfo;
> +
> + if (max_devs <= 0) {
> + return;
> + }
> +
> + QTAILQ_FOREACH(dinfo, &drives, next) {
> + if (dinfo->type == type) {
> + fprintf(stderr, "Cannot override units-per-bus property of"
> + " the %s interface, because a drive of that type has"
> + " already been added.\n", if_name[type]);
> + g_assert_not_reached();
> + }
I'd prefer a straightforward
QTAILQ_FOREACH(dinfo, &drives, next) {
assert(dinfo->type != type);
}
or even
assert(QTAILQ_EMPTY(drives));
assuming it actually holds.
> + }
> +
> + if_max_devs[type] = max_devs;
> +}
> +
> /*
> * We automatically delete the drive when a device using it gets
> * unplugged. Questionable feature, but we can't just drop it.
> diff --git a/include/sysemu/blockdev.h b/include/sysemu/blockdev.h
> index 80f768d..f23d495 100644
> --- a/include/sysemu/blockdev.h
> +++ b/include/sysemu/blockdev.h
> @@ -46,6 +46,8 @@ struct DriveInfo {
> QTAILQ_ENTRY(DriveInfo) next;
> };
>
> +void override_max_devs(BlockInterfaceType type, int max_devs);
> +
> DriveInfo *drive_get(BlockInterfaceType type, int bus, int unit);
> bool drive_check_orphaned(void);
> DriveInfo *drive_get_by_index(BlockInterfaceType type, int index);
