El 06/01/15 a les 14.19, Bob Liu ha escrit: > When there is no enough free grants, gnttab_alloc_grant_references() > will fail and block request queue will stop. > If the system is always lack of grants, blkif_restart_queue_callback() can't > be > scheduled and block request queue can't be restart(block I/O hang). > > But when there are former requests complete, some grants may free to > persistent_gnts_c, we can give the request queue another chance to restart and > avoid block hang. > > Reported-by: Junxiao Bi <junxiao...@oracle.com> > Signed-off-by: Bob Liu <bob....@oracle.com> > --- > drivers/block/xen-blkfront.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c > index 2236c6f..dd30f99 100644 > --- a/drivers/block/xen-blkfront.c > +++ b/drivers/block/xen-blkfront.c > @@ -1125,6 +1125,17 @@ static void blkif_completion(struct blk_shadow *s, > struct blkfront_info *info, > } > } > } > + > + /* > + * Request queue would be stopped if failed to alloc enough grants and > + * won't be restarted until gnttab_free_count >= info->callback->count. > + * > + * But there is another case, once we have enough persistent grants we > + * can try to restart the request queue instead of continue to wait for > + * 'gnttab_free_count'. > + */ > + if (info->persistent_gnts_c >= info->callback.count) > + schedule_work(&info->work);
I guess I'm missing something here, but blkif_completion is called by blkif_interrupt, which in turn calls kick_pending_request_queues when finished, which IMHO should be enough to restart the processing of requests. Roger. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
