On 10/25/2017 11:27 AM, Omar Sandoval wrote: > On Wed, Oct 25, 2017 at 12:04:45PM -0600, Jens Axboe wrote: >> If an IO scheduler is selected via elevator= and it doesn't match >> the driver in question wrt blk-mq support, then we fail to boot. >> >> The elevator= parameter is deprecated and only supported for >> non-mq devices. Augment the elevator lookup API so that we >> pass in if we're looking for an mq capable scheduler or not, >> so that we only ever return a valid type for the queue in >> question. >> >> Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=196695 >> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> >> --- >> block/elevator.c | 44 +++++++++++++++++++++----------------------- >> 1 file changed, 21 insertions(+), 23 deletions(-) >> >> diff --git a/block/elevator.c b/block/elevator.c >> index 7ae50eb2732b..b70e69f795db 100644 >> --- a/block/elevator.c >> +++ b/block/elevator.c >> @@ -83,12 +83,15 @@ bool elv_bio_merge_ok(struct request *rq, struct bio *bio) >> } >> EXPORT_SYMBOL(elv_bio_merge_ok); >> >> -static struct elevator_type *elevator_find(const char *name) >> +/* >> + * Return scheduler with name 'name' and with matching 'mq capability >> + */ >> +static struct elevator_type *elevator_find(const char *name, bool mq) >> { >> struct elevator_type *e; >> >> list_for_each_entry(e, &elv_list, list) { >> - if (!strcmp(e->elevator_name, name)) >> + if (!strcmp(e->elevator_name, name) && !(mq ^ e->uses_mq)) > > > How about just (mq == e->uses_mq)? That is simpler/cleaner, I'll make that adjustment. Not sure where the XOR temptation came from. -- Jens Axboe
