Re: [PATCH 3/4] scsi: hisi_sas: Make sg_tablesize consistent value

[John Garry <john.garry@xxxxxxxxxx>]

On 21/11/2018 11:08, Steffen Maier wrote:
> On 11/21/2018 12:02 PM, Steffen Maier wrote:
> > On 11/20/2018 03:59 PM, John Garry wrote:
> > > From: Xiang Chen <chenxiang66@xxxxxxxxxxxxx>
> > >
> > > Sht->sg_tablesize is set in the driver, and it will be assigned to
> > > shost->sg_tablesize in SCSI mid-layer. So it is not necessary to
> > > assign shost->sg_table one more time in the driver.
> > >
> > > In addition to the change, change each scsi_host_template.sg_tablesize
> > > to HISI_SAS_SGE_PAGE_CNT instead of SG_ALL.
> >
> > Might be completely irrelevant, so just as information: I once had
> > problems due to changing (reducing) SHT.sg_tablesize because block
> > queue limits of BSG devices of Scsi_Host and fc_host (not sure if you
> > have an equivalent bsg device for your transport(s)) inherit from SHT,
> > but don't update (automatically) on later updates of
> > shost->sg_tablesize, which in turn affect scsi_devices allocated after
> > the shost update.
> > Cf.
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/s390/scsi?id=5fea4291deacd80188b996d2f555fc6a1940e5d4
>
>
> Figured, your new constant seems to have the same value so no problem.

Right, so previously we were doing similar to what you describe - 
setting the value in the SHT and then setting shost->sg_tablesize after 
the host is allocated.

However the values were the same, so in this patch we're just removing 
setting shost->sg_tablesize (again).

Thanks,
John

> #define SG_CHUNK_SIZE    128
> #define SG_ALL    SG_CHUNK_SIZE
> #define HISI_SAS_SGE_PAGE_CNT SG_CHUNK_SIZE
>
> > ("[SCSI] zfcp: block queue limits with data router")
> > if you need more details.
> >
> > > Signed-off-by: Xiang Chen <chenxiang66@xxxxxxxxxxxxx>
> > > Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
> > > ---
> > >   drivers/scsi/hisi_sas/hisi_sas_main.c  | 1 -
> > >   drivers/scsi/hisi_sas/hisi_sas_v1_hw.c | 2 +-
> > >   drivers/scsi/hisi_sas/hisi_sas_v2_hw.c | 2 +-
> > >   drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 3 +--
> > >   4 files changed, 3 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c
> > > b/drivers/scsi/hisi_sas/hisi_sas_main.c
> > > index d13a662..cbda48e 100644
> > > --- a/drivers/scsi/hisi_sas/hisi_sas_main.c
> > > +++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
> > > @@ -2410,7 +2410,6 @@ int hisi_sas_probe(struct platform_device *pdev,
> > >       shost->max_lun = ~0;
> > >       shost->max_channel = 1;
> > >       shost->max_cmd_len = 16;
> > > -    shost->sg_tablesize = min_t(u16, SG_ALL, HISI_SAS_SGE_PAGE_CNT);
> > >       if (hisi_hba->hw->slot_index_alloc) {
> > >           shost->can_queue = hisi_hba->hw->max_command_entries;
> > >           shost->cmd_per_lun = hisi_hba->hw->max_command_entries;
> > > diff --git a/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
> > > b/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
> > > index d24342b..2d035cc 100644
> > > --- a/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
> > > +++ b/drivers/scsi/hisi_sas/hisi_sas_v1_hw.c
> > > @@ -1815,7 +1815,7 @@ static int hisi_sas_v1_init(struct hisi_hba
> > > *hisi_hba)
> > >       .change_queue_depth    = sas_change_queue_depth,
> > >       .bios_param        = sas_bios_param,
> > >       .this_id        = -1,
> > > -    .sg_tablesize        = SG_ALL,
> > > +    .sg_tablesize        = HISI_SAS_SGE_PAGE_CNT,
> > >       .max_sectors        = SCSI_DEFAULT_MAX_SECTORS,
> > >       .use_clustering        = ENABLE_CLUSTERING,
> > >       .eh_device_reset_handler = sas_eh_device_reset_handler,
> > > diff --git a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
> > > b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
> > > index e78a97e..79e58a7 100644
> > > --- a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
> > > +++ b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
> > > @@ -3570,7 +3570,7 @@ struct device_attribute *host_attrs_v2_hw[] = {
> > >       .change_queue_depth    = sas_change_queue_depth,
> > >       .bios_param        = sas_bios_param,
> > >       .this_id        = -1,
> > > -    .sg_tablesize        = SG_ALL,
> > > +    .sg_tablesize        = HISI_SAS_SGE_PAGE_CNT,
> > >       .max_sectors        = SCSI_DEFAULT_MAX_SECTORS,
> > >       .use_clustering        = ENABLE_CLUSTERING,
> > >       .eh_device_reset_handler = sas_eh_device_reset_handler,
> > > diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
> > > b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
> > > index 7e2b020..8a08078 100644
> > > --- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
> > > +++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
> > > @@ -2224,7 +2224,7 @@ struct device_attribute *host_attrs_v3_hw[] = {
> > >       .change_queue_depth    = sas_change_queue_depth,
> > >       .bios_param        = sas_bios_param,
> > >       .this_id        = -1,
> > > -    .sg_tablesize        = SG_ALL,
> > > +    .sg_tablesize        = HISI_SAS_SGE_PAGE_CNT,
> > >       .max_sectors        = SCSI_DEFAULT_MAX_SECTORS,
> > >       .use_clustering        = ENABLE_CLUSTERING,
> > >       .eh_device_reset_handler = sas_eh_device_reset_handler,
> > > @@ -2366,7 +2366,6 @@ struct device_attribute *host_attrs_v3_hw[] = {
> > >       shost->max_lun = ~0;
> > >       shost->max_channel = 1;
> > >       shost->max_cmd_len = 16;
> > > -    shost->sg_tablesize = min_t(u16, SG_ALL, HISI_SAS_SGE_PAGE_CNT);
> > >       shost->can_queue = hisi_hba->hw->max_command_entries -
> > >           HISI_SAS_RESERVED_IPTT_CNT;
> > >       shost->cmd_per_lun = hisi_hba->hw->max_command_entries -