Hi Jens Sorry to trouble you, I am very sorry for taking it for granted for the patch compile. I checked, compile for the two changed files are OK: block/blk-core.c block/blk-mq-sched.c Compile failed for the function in below header file: include/linux/blk-mq.h: request_to_qc_t() - if (rq->tag != -1) + if (rq->tag != BLK_MQ_NO_TAG) BLK_MQ_NO_TAG is defined in 'block/blk-mq-tag.h', if I include this header file in 'include/linux/blk-mq.h' via '#include "../../block/blk-mq-tag.h"', Many other similar compile failed happen, for example: In file included from ./include/linux/../../block/blk-mq-tag.h:5:0, from ./include/linux/blk-mq.h:8, from block/blk.h:6, from block/bio.c:24: ./include/linux/../../block/blk-mq.h:21:29: error: ‘HCTX_MAX_TYPES’ undeclared here (not in a function); did you mean ‘KOBJ_NS_TYPES’? struct list_head rq_lists[HCTX_MAX_TYPES]; ^~~~~~~~~~~~~~ If I moved below BLK_MQ_NO_TAG definition to 'include/linux/blk-mq.h', all kernel compiles are ok with the patch. enum { BLK_MQ_NO_TAG = -1U, BLK_MQ_TAG_MIN = 1, BLK_MQ_TAG_MAX = BLK_MQ_NO_TAG - 1, }; Will you accept above moving of BLK_MQ_NO_TAG to 'include/linux/blk-mq.h'? Thanks -----Original Message----- From: Jens Axboe [mailto:axboe@xxxxxxxxx] Sent: Monday, August 24, 2020 4:58 AM To: tianxianting (RD) <tian.xianting@xxxxxxx>; ast@xxxxxxxxxx; daniel@xxxxxxxxxxxxx; kafai@xxxxxx; songliubraving@xxxxxx; yhs@xxxxxx; andriin@xxxxxx; john.fastabend@xxxxxxxxx; kpsingh@xxxxxxxxxxxx Cc: linux-block@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx Subject: Re: [PATCH] blk-mq: use BLK_MQ_NO_TAG for no tag On 8/23/20 9:44 AM, Xianting Tian wrote: > Replace various magic -1 constants for tags with BLK_MQ_NO_TAG. Doesn't look like this patch was even compiled... -- Jens Axboe