On 8/30/22 4:05 PM, Bart Van Assche wrote:
> Instead of using scsi_host_template members to track the SCSI proc
> directory entries, track these entries in a list. This patch changes the
> time needed for looking up the proc dir pointer from O(1) into O(n). I
> think this is acceptable since the number of SCSI host adapter types per
> host is usually small (less than ten).
>
> This patch has been tested by attaching two USB storage devices to a
> qemu host:
>
> }
> @@ -149,15 +214,17 @@ void scsi_proc_hostdir_rm(struct scsi_host_template *sht)
> void scsi_proc_host_add(struct Scsi_Host *shost)
> {
> struct scsi_host_template *sht = shost->hostt;
> + struct scsi_proc_entry *e;
> struct proc_dir_entry *p;
> char name[10];
>
> - if (!sht->proc_dir)
> */
> void scsi_proc_host_rm(struct Scsi_Host *shost)
> {
> + struct scsi_proc_entry *e;
> char name[10];
>
> - if (!shost->hostt->proc_dir)
Hey Bart, Would it better to replace those two checks with a
if (!sht->show_info)
return;
like is done in scsi_proc_hostdir_add/scsi_proc_hostdir_rm? In those
hostdir functions if show_info is not set, you will not add an entry to
scsi_proc_list. So in the above functions if that callout is not set
you know there is no entry on &scsi_proc_list and don't need to grab the
global_host_template_mutex for those cases.
I can't really test but someone did say they had 1000s of scsi_hosts for
iscsi. I'm not really sure how big a deal it is since we wouldn't be
doing a lot of work with that mutex hold, but it seems like a simple and
nice change just in case.
