On Wed, 13 Oct 2021 15:00:07 -0700 Bart Van Assche <bvanassche@xxxxxxx> wrote: > On 10/12/21 11:50 PM, Yanling Song wrote: > > On Tue, 12 Oct 2021 09:59:30 -0700 > > Bart Van Assche <bvanassche@xxxxxxx> wrote: > >> Why is it that SG_IO is not sufficient? This is something that > >> should have been explained in the patch description. > > > > There are two cases that there are no SG devices and SG_IO cannot > > work. 1. To access raid controller: > > a. Raid controller is a scsi host, not a scsi device, so there > > is no SG device associated with it. > > b. Even there is a scsi device for raid controller, SG_IO > > cannot work when something wrong with IO queue and only admin queue > > can work; > > 2. To access the physical disks behinds raid controller: > > raid controller only reports VDs to OS and only VDs have SG > > devices. OS has no idea about physical disks behinds raid > > controller and there is no SG devices associated with physical > > disks. > > Please take a look at the bsg_setup_queue() call in ufs_bsg_probe(). > That call associates a BSG queue with the UFS host. That queue > supports requests of type struct ufs_bsg_request. The Fibre Channel > transport driver does something similar. I believe that this is a > better solution than introducing entirely new ioctls. I need some time to investigate it. will response later. > > >>>> Additionally, mixing driver-internal and user space definitions > >>>> in a single header file is not OK. Definitions of data > >>>> structures and ioctls that are needed by user space software > >>>> should occur in a header file in the directory > >>>> include/uapi/scsi/. > >>> > >>> Sounds reasonable. But after checking the directory > >>> include/uapi/scsi/, there are only several files in it. It is > >>> expected that there should be many files if developers follow the > >>> rule. Do you know why? > >> > >> If this rule is not followed, that will be a red flag for the SCSI > >> maintainer and something that will probably delay upstream > >> acceptance of this patch. > > > > Since there are not much examples in include/uapi/scsi/, what' your > > suggestion on how to put the definitions into the folder? for > > example, what's the file name? spraid_ioctrl.h? > > How about include/uapi/scsi/spraid.h, since I assume that that header > file will cover all user space interfaces for interaction with the > spraid driver? > > Thanks, > > Bart. >
