On 12/14/18 12:11 PM, Bart Van Assche wrote: > On Fri, 2018-12-14 at 19:39 +0800, Ming Lei wrote: >> static void print_stat(struct seq_file *m, struct blk_rq_stat *stat) >> { >> @@ -856,6 +857,15 @@ int blk_mq_debugfs_register(struct request_queue *q) >> goto err; >> } >> >> + if (q->rq_qos) { >> + struct rq_qos *rqos = q->rq_qos; >> + >> + while (rqos) { >> + blk_mq_debugfs_register_rqos(rqos); >> + rqos = rqos->next; >> + } >> + } > > Have you considered to use a for-loop instead of a while loop? That would > allow to remove the if-statement and hence would make the code more compact. It would fit better with the style in that code do to: rqos = q->rq_qos; while (rqos) { .... rqos = rqos->next; } > >> +int blk_mq_debugfs_register_rqos(struct rq_qos *rqos) >> +{ >> + struct request_queue *q = rqos->q; >> + char *dir_name = rq_qos_id_to_name(rqos->id); > > Please change "char *" into "const char *". > >> enum rq_qos_id { >> RQ_QOS_WBT, >> RQ_QOS_CGROUP, >> @@ -22,6 +26,9 @@ struct rq_qos { >> struct request_queue *q; >> enum rq_qos_id id; >> struct rq_qos *next; >> +#ifdef CONFIG_BLK_DEBUG_FS >> + struct dentry *debugfs_dir; >> +#endif >> }; > > The indentation of "debugfs_dir" looks odd to me. > >> +static inline char *rq_qos_id_to_name(enum rq_qos_id id) >> +{ >> + switch (id) { >> + case RQ_QOS_WBT: >> + return "wbt"; >> + case RQ_QOS_CGROUP: >> + return "cgroup"; >> + } >> + return "unknown"; >> +} > > Same comment here as earlier: please use "const char *" instead of "char *" > for constant strings. Otherwise this patch looks fine to me. Agree on the rest of your comments. -- Jens Axboe